Strand7 Webnotes - ST7-1.40 Applications

ST7-1.40 Applications
ST7-1.40.10 Applications / Aerospace
1.2 MB	ST7-1.40.10.1 Autofrettage of a Composite-Metallic Tank This document is intended as a demonstration of how Strand7 can be used to model and solve non-linear material problems in axisymmetric structures. The use of axisymmetric and plate/shell elements is also covered. Another tank model of interest is found in ST7-1.40.50.1 Modelling a Composite Tank. A composite pressure vessel with aluminium liner is subjected to an internal pressure intended to cause plastic deformation of the aluminium liner. In this demonstration a simplified representation...
1.1 MB	ST7-1.40.10.3 Analysis of Rocket Inertial Effects with Fuel and Payload Rockets are capable of high-G manoeuvring, which enables them to take tighter turns than the targeted aircraft. When such a turn is entered, the structure is highly loaded by the inertia of the payload, structural mass and fuel mass. Strand7 can be used to model such an event by using the Inertia Relief solver, which produces analysis results for structure which is not restrained, such as aircraft, floating ships and rockets. Additionally, the consideration of a fuel payload can be distributed...
1.1 MB	ST7-1.40.10.7 Panel Buckling Analysis A 1 m x 3 m stiffened aluminium panel is subjected to pressurised overloading to determine post-buckling behaviour. Five ribs and two hat stringers provide support to the skin.
1.8 MB	ST7-1.40.10.8 PSD Analysis of a Wing-Mounted Missile A wing-mounted missile is subjected to the severe vibrational environment of a performance fighter wing. This analysis outlines how to load a rocket using a power spectral density curve and Strand7s spectral response solver. This analysis is based on data from the F-15B fighter, provided by NASA [1] . A Sidewinder missile model [2] will be used to investigate the response of the missile and contained propellant to the given vibrational environment. The goal of the analysis is to investigate...
ST7-1.40.20 Applications / Marine
3.1 MB	ST7-1.40.20.1 Strand7 and Marine Structures Strand7 is a general-purpose structural finite element analysis package that has been developed to meet the requirements of practising engineers across all engineering disciplines including naval architecture. These notes summarise how Strand7 can be used to conduct FEA on a typical marine structure by highlighting various features and tools, concluding with an example. A typical frame in marine structures consists of thin panels and stiffeners. Material properties are defined by choosing...
0.5 MB	ST7-1.40.20.2 Underwater Cable - Catenary and Forces Strand7 is equipped with cable elements which can be used to determine the catenary shape due to gravity, distributed loads and concentrated loads. This document shows an example of cable elements used to solve an underwater cable system. A 1000 m underwater cable consisting of metal chains and wire rope is shown below. Create a new SI unit model. Create a beam element joining nodes at (0,0,0) and (500,500,0). Use Tools/Split Beams with a 0.3 Split Ratio to divide the beam into two elements. ...
2.5 MB	ST7-1.40.20.3 Buoyancy and Stability Analysis of Floating Structures Strand7 provides tools to model offshore floating structures such as boats subject to buoyant forces, payload and other loadings. A standard residential pontoon decking is supported by four 1200 L flotation modules. To determine the submerged level of the deck at steady state. To determine the displacement of the deck with a full payload. To observe the effect of ballast weight on stability. The model is set up as follows: The first step is to apply unit normal pressure to the pontoon...
1.5 MB	ST7-1.40.20.4 Transverse Stability of a Ship This Webnote describes the techniques that can be used to determine the centre of gravity, centre of buoyancy, metacentre and rolling period of a ship, and produce its curve of statical stability. The results are then verified by a set of analytical solutions.
7.0 MB	ST7-1.40.20.5 Dynamic Impact Analysis of a Moored Ship Buoyancy effects on marine structures can be analysed to determine the dynamic response of floating structures. In this Webnote we consider the effect of a strong wind on a moored tugboat. Contact is defined between the mooring dolphin and ship. Cable elements connect the ship to the dolphin.
0.5 MB	ST7-1.40.20.6 Sub-Sea Cable Tensioning Analysis The catenary cable is a line element with a free length that can be different to the distance between the nodes to which it is connected. This allows the element to droop under the action of gravity or global accelerations. The string group attribute is a very powerful attribute that facilitates the modelling of cable or string-like connections, where a cable is connected to a node, but can freely slide through that node. It is analogous to the modelling of a frictionless pulley.
0.8 MB	ST7-1.40.20.7 Progressive Lift of a Weighted Mooring Line The anchor of a 40' boat is set and the boat is subjected to wind load. The anchor rode consists of 5/8" three-strand Nylon and 5/16" Proof Coil steel chain (1.09 lb/ft). Some 5.0 lbs sinkers have been added to the chain to help keep the pull horizontal. The objective is to determine the required wind force on the boat to lift the chain off the seabed.
ST7-1.40.30 Applications / Civil
4.9 MB	ST7-1.40.30.2 Fluid-Structure Interaction Tank Sloshing Analysis This document illustrates how to construct and analyse in Strand7, a model of an LNG (Liquefied Natural Gas) filled concrete tank resting on buried piles. Create a new Strand7 file. Choose SI units. Choose Global/Coordinate Systems, Create a Cylindrical UCS of XY type at (0,0,0). This will create a cylindrical UCS, which will be referred to often throughout the modelling process. Create a set of nodes referenced to the cylindrical UCS: Choose View/Angles and change to a ZX Plane...
1.0 MB	ST7-1.40.30.3 Lateral Earth Pressure and Retaining Walls Lateral earth pressure is one of the most important factors to be considered when designing retaining walls, or indeed, for designing any structure that interacts with soil. This Webnote demonstrates the application of Strand7 in the calculation of lateral earth pressure and analysis of retaining walls by using the nonlinear static solver.
0.5 MB	ST7-1.40.30.4 Cable Systems Strand7 has the ability to model cable-pulley systems and catenary cables under gravity and applied loads. An example of a simplified elevated ski lift structure is demonstrated here. Create a new file and set the units to Nmm. Create a few vertical beams representing the cable support columns using Create/Element and Snap Grid or by entering node locations with Create/Node. Connect them with beam elements representing the cables. In the model shown at right, beam taper attributes...
0.7 MB	ST7-1.40.30.6 Dam-Soil Interaction Static and Dynamic Loading Dams are complex structures which interact with the surrounding environment due to their massive size. This interaction is analysed using a simple dam model for a 1G static and El Centro earthquake dynamic conditions. The simple dam model is shown at right. It is a mildly arched dam sitting on fill between two rock walls. It was formed using manual meshing techniques including extrusion, copying and scaling by a cylindrical coordinate system to form the arch curvature. All nodes at interfaces...
1.1 MB	ST7-1.40.30.11 Construction Sequence Analysis of Tunnelling in Soils Tunnelling and excavation are common practice in civil and geotechnical engineering, so prediction of the mechanical behaviour of soil and structure is very important for design. However, due to the complexity of soil conditions, such as groundwater level (or water table), in-situ stresses and void ratio etc., and the staged characteristics of tunnelling and excavation procedures, accurate prediction of soil-structure interaction is also very challenging. Strand7 provides a staged (construction...
0.9 MB	ST7-1.40.30.22 Analysis of Soil Slope Stability Using Strand7 Soil slope stability analysis is an important subject in civil engineering for the design of roads, railways, dams, and so on. This Webnote presents an example of using Strand7 to investigate soil slope stability and to find a critical state of a slope under a given condition.
ST7-1.40.35 Applications / Structural
2.0 MB	ST7-1.40.35.1 Glass Facade Blast Loading Glass Facade construction is subject to blast loading requirements. These unique structures come in a variety of custom configurations suited to the particular needs of each installation. Due to the variability of each design, Finite Element Analysis can be a very powerful and cost-effective tool in the qualification of these structures. An example glass facade is shown at right. A joint detail is shown below, with the mounting hardware in green, and backing structure in orange and a post-tensioned...
1.1 MB	ST7-1.40.35.2 Extracting Resultant Forces and Moments from a Building This Webnote explains how to extract actions from an entire building or portion of a building. Four related procedures are illustrated: Finding the centre of mass of a building (in plan). Finding the centre of stiffness (the shear centre) for a particular storey of a building. Using staging to analyse multiple scenarios in a single model. Finding the resultant actions on a particular storey of a building. The first two procedures are particularly useful in seismic analysis because...
1.3 MB	ST7-1.40.35.4 Modelling Timber as an Orthotropic Material An orthotropic material is defined as having three mutually orthogonal axes. The structural response depends on the material's orientation with respect to the loading. Wood may be characterised as an orthotropic material...
1.4 MB	ST7-1.40.35.5 Reinforced Concrete Slab Ductility Several methods to model reinforced concrete are discussed and compared using a typical 200 mm thick slab. The most detailed approach is to model the concrete with layers of brick elements and the reinforcing bars as beam elements embedded within. Other options include replacing the reinforcing beam elements with a smeared layer of plate mesh with equivalent cross-section area and/or replacing the concrete brick mesh with an equivalent plate mesh.
1.9 MB	ST7-1.40.35.6 Modelling Post Tensioned Concrete in Strand7 Given that Strand7 is a general purpose FEA package rather than a specialised prestressed concrete (PSC) design package, users may not be aware of the potential for Strand7 to analyse PSC structures. This document outlines one method for modelling a post-tensioned one-way slab (150mm thick) and transverse band beams (400mm deep) with discrete draped bonded tendons. In addition to self-weight and prestress, the slab will be subjected to a 1 kPa superimposed dead load and a 7.5 kPa live load. ...
1.9 MB	ST7-1.40.35.7 Kalzip Corrugated Roofing Kalzip corrugated roofing is an aluminium sheet product used to build large, sometimes highly complex roofing and cladding structures. It is flexible enough to form attractive contours and is featured on well known architectural designs, such as Melbournes Southern Cross Station. Strand7 can be used to analyse design details under load and improve or verify existing designs. Kalzip features an interlocking design which simplifies installation. Kalzip provides DXF geometry of common...
0.8 MB	ST7-1.40.35.8 Modelling Tension-Only or Compression-Only Structural Members Many structural members and connections have different tensile and compressive behaviour. Typical structural features which are compression-only include contact and bearing situations, whilst tension-only members often include bolts, bracing, cables, ropes or chains. Nonlinear analysis is generally required to consider such members, as it is often not known beforehand which members will be in tension and which members will be in compression, particularly in complex structures.
0.8 MB	ST7-1.40.35.11 Modelling Friction Pendulum Seismic Isolation Bearings Friction Pendulums seismic isolators are used for isolating earthquake movements from the buildings they support, thus protecting the buildings from earthquake damage. These bearings also dissipate energy associated with relative movement between the building and the ground by their hysteretic behaviour. Typical response of a single isolator is schematically illustrated on the right where FL and DL are the lateral force and displacement, respectively. The stiffness associated with slippage (step...
1.2 MB	ST7-1.40.35.13 Analysis of Blast Resistant Structures The design of blast resistant structure in hostile environments has previously been limited to nonlinear single degree of freedom (SDOF) approximations, which limits the analysis to point-wise design checking of individual members. This Webnote will draw on the experience of blast loading developed in UFC 3-340-02[1] and apply it to a nonlinear transient blast analysis using Strand7. The example problem, Example 2A-10 found in [1], is replicated using FEA. The resulting acceleration, velocity...
0.4 MB	ST7-1.40.35.14 Modelling Nonlinear Behaviour of Steel Reinforced Concrete Steel reinforced concrete beams and columns are composite structures consisting of two very different materials. Steel has high stiffness and yield in both tension and compression whereas concrete has little strength in tension (cracks under tension). These different nonlinear material behaviours can be captured using different material models and stress-strain curves in Strand7. In the modelling sense, steel reinforced concrete beams and columns can be modelled in a variety of ways including: ...
1.4 MB	ST7-1.40.35.15 Extracting Shear Wall Design Action Effects This Webnote describes a simple method for extracting the design action effects to be used for the design of shear walls. In order to provide a thorough explanation of the method, four models will be discussed: Consider the shear wall subjected to three lateral point loads shown opposite. The wall is fixed at the base, and grouped into three levels, each 4m in height. The wall is idealised as a cantilever beam and the shear forces and bending moments are calculated as shown on the following...
1.7 MB	ST7-1.40.35.22 AS 1170.4-2007 Earthquake Analysis in Strand7 This Webnote introduces Strand7 functionality that can be used in an earthquake analysis of a structure in accordance with AS1170.4-2007, the Australian Standard for earthquake action. The design code covers three main forms of analysis, namely Equivalent Static, Modal Response Spectrum, and Time History analysis.
0.8 MB	ST7-1.40.35.27 Tapered Circular Steel Towers Tapered steel towers are common due to simplicity and low cost. These towers are sometimes faceted, but often circular in cross-section. This Webnote covers the basic modelling of a tapered circular tower, comparing a plate mesh with a tapered beam element approach. The structure is a simple tower which tapers from 2 m diameter at the bottom to 1 m diameter at the top. Thickness is a constant 10 mm. The model geometry is most easily generated by drawing the axisymmetric cross-section...
1.1 MB	ST7-1.40.35.32 Column Interaction Diagrams This Webnote outlines procedures to create Moment vs Axial Force and Moment vs Curvature diagrams. A rectangular hollow section is studied. The example follows the European Code EC2 design assumptions, but the procedure is similar for other codes. Choose File/New and create a new model with units of Nmm. Choose Create/Node to create nodes at the following positions: (X=0; Y=0; Z=0); (X=1000; Y=0; Z=0); (X=0; Y=1500; Z=0); (X=1000; Y=1500; Z=0). Choose Create/Element, set Quad4 as...
1.0 MB	ST7-1.40.35.36 Cable Net Analysis This Webnote describes a simple analysis of a 3D cable structure in Strand7 using the Nonlinear Static and Nonlinear Transient Dynamic solvers. All flexible members such as cables and wires in this type of structure can be modelled as Truss elements. These are axial force elements and do not provide lateral stiffness unless there is some tensile force in them. Therefore a pre-load attribute is usually applied to provide some lateral stiffness and assist solver convergence. Given the inherent...
0.5 MB	ST7-1.40.35.48 Precast Slab Lifting Analysis with String Groups Precast slabs or walls are often lifted into place by crane and straps. In this analysis we model the lifting situation in which there are three pulleys arranged in a load-sharing scheme similar to a whiffle tree. Three independent cables support the panel, each with a pulley at the top. The model is a simple 2D beam model, although more complex 3D scenarios could also be modelled. The goal of this Webnote is to show how string groups work to model pulleys, and to evaluate the proposed lifting...
1.3 MB	ST7-1.40.35.49 Modelling Bond Slip in Reinforced Concrete Tensile stress is generated in steel reinforcing bars via shear stress at the interface between the concrete and reinforcement. This shear stress is referred to as bond stress. If the bond stress exceeds the local shear capacity at the interface, the bar may slip relative to the concrete. This Webnote examines the implementation of a nonlinear bond stress vs slip relationship in Strand7.
ST7-1.40.40 Applications / Mechanical
2.2 MB	ST7-1.40.40.1 Fatigue Analysis of a Welded Connection Many structures are subjected to cyclical loads of relatively small magnitude but with a large number of cycles. Structures under this type of loading may be required to be analysed for fatigue endurance to determine their working life. There are many design standards that stipulate the fatigue requirements of various types of structures such as for pressure vessels (BS 5500, with newer versions referred to as PD 5500), steel, concrete and composite bridges (BS 5400, AASHTO LRFD Section 6.6), and steel structures (BS 7608, BS EN 1993-1-9:2005, AS 4100). The methods of analysis outlined in this Webnote use terminology and notation consistent with BS 7608, BS 5500 and EN 1993-1-9, but aim to be general enough to be applied to other fatigue design codes.
1.1 MB	ST7-1.40.40.3 Analysis of a Welded Clip A welded clip is fabricated to join two parts in transit. The clip consists of two angles welded along two connecting seams. The two angles are shown in red and blue at right, with green fillet welds. The blue angle has slotted holes to avoid overloading in the vertical direction. The clip will be modelled using shell elements, rigid links and contact elements. The supporting structure behind the clip will be represented by compression-only face support attributes. Shell models are...
0.8 MB	ST7-1.40.40.4 Analysis of Pressure Vessels using AS1210 - 1997 AS 1210 1997 Appendix B concerns the application of FEA to the design of pressure vessels. A few key points and how to apply them to Strand7 are paraphrased (in italics) and addressed below. FEA should only be used alongside traditional techniques. FEA is a complex analysis technique which shouldnt be relied upon in isolation if alternative methods of analysis and/or testing are available. Linear static analysis is the most typical type of FE analysis. Strand7 allows for the contouring...
1.9 MB	ST7-1.40.40.6 Modelling Hydraulic Actuation This Webnote is a continuation of the automeshing Webnote ST7-1.50.10.2 Surface Automeshing an Excavator Assembly. In this continuation, we apply hydraulic actuators to force the digger arm mechanism through the range of motion. We will use stiff truss elements with pre-strain attributes which, when scaled, produce an actuating effect through contraction and expansion. There are three lugs which are pivots between parts in the assembly, and five lugs which connect hydraulic actuators between...
0.8 MB	ST7-1.40.40.8 Extensional Behaviour of Pressurised Curved Pipes Curved pipes with non-circular cross-sections tend to straighten when pressurised, as the cross-sectional profile tries to stretch into a circle. Curved pipes with a perfectly circular cross-section do not experience this phenomenon. However, curved pipes are often developed by a rolling-forming operation which leaves the cross-section slightly non-circular. This in turn can lead to extensional effects in formed piping. Create a new model with Nmm units. Activate the snap grid, and set...
1.1 MB	ST7-1.40.40.22 Applying Pad Eye Loads This Webnote illustrates some common techniques to apply loading to a pad eye modelled with plates and bricks. We will look at several configurations to apply a force of approximately 1.4 kN to the pad eye: Rigid Connection Multi-Point Link Contact Elements Uneven Load Distribution with Bolt Pressure Distribution To create rigid connection, use Tools/Auto Assign/Restraints/Rigid Connections and then apply appropriate loading to the master node. Pros Can be used in both...
6.2 MB	ST7-1.40.40.23 Foundation Vibration Analysis The vibration of foundations supporting machinery must be checked to prevent damage to the machinery and connected structure. The Harmonic Response Solver can be used to do this. A code focused approach is taken based on ISO 10816 and DIN 4024. The model is built from CAD geometry and modified as necessary. The attached machinery vibrates due to out of balance rotating mass caused by tolerances and the large rotating masses involved in typical industrial machinery. We will define the...
3.0 MB	ST7-1.40.40.27 Modelling Interference Fits by Using Shrink Links Interference fits (shrink fits, or press fits) are commonly used in mechanical engineering for various purposes, such as holding parts together, transferring power or load, and introducing compressive stresses in parts. In this Webnote, we use Shrink links to analyse interference fits in various situations.
3.5 MB	ST7-1.40.40.28 Modelling Interference Fits by Using Contact Elements Interference fits (shrink fits, or press fits) are commonly used in mechanical engineering for various purposes, such as holding parts together, transferring power or load, and introducing compressive stresses in parts. In this Webnote, we use contact elements to analyse interference fits in various situations.
0.7 MB	ST7-1.40.40.33 Press Fit Shaft Extension Torsional Analysis A shaft is to be extended with a press fit interface. The torsion capability of the new joint is explored by using contact elements with friction. The shaft extension is heated and the contact elements are placed between the two parts, such that when it is cooled a pre-load is generated in the contact elements. This radial load then creates friction in the joint when a torque is applied.
ST7-1.40.50 Applications / Composites
4.0 MB	ST7-1.40.50.1 Modelling a Composite Tank The analysis of composite structures is more complex than metallic structures because it requires the definition of ply properties, laminate stacks and element directions. The tank geometry is shown below. The tank body is filament wound, with 5mm stainless steel reinforced penetrations. It is fitted into a stainless steel support collar. Six lifting lugs are provided. This CAD geometry is imported into Strand7 using the IGES format. The tank is composed of filament-wound VTM266-1 700gsm...
1.2 MB	ST7-1.40.50.2 Modelling a Composite Bracket Thick curved composite parts prove challenging to design, analyse and manufacture due to the orthotropic properties of the constituent plies. A 10 mm thick three-tab CFRP bracket is shown below. At left, the thick CAD solid part is shown. At middle, the equivalent mid-surface geometry is shown. This is used to generate a surface automesh of plate elements (shown at right) which has a laminate property definition applied. Approximate model size is 100 mm. / / / The bolt pattern...
2.2 MB	ST7-1.40.50.3 Modelling a Composite Pultruded Rail Pultrusion is a continuous composites manufacturing technique whereby fibre is pulled through a series of processing steps, resulting in a cured continuous shape. Pultrusion typically consists of a unidirectional fibre core, with the ability to add a continuous braid around the outside. In this example we will cover the stress analysis of a handrail subject to bending and external pressure loads. On half of the symmetric geometry of a pultruded composite stairway is shown below. The IGES geometry...
0.9 MB	ST7-1.40.50.4 Composites with Core Laminate composites often employ a light-weight core to increase the section depth which increases the stiffness and strength in bending. Modelling core in Strand7 can be achieved in a few different ways we will cover the two most common methods in this document: as a ply definition and as a solid (brick) element between two plate elements. The simplest way to model core is to include it as a ply in the laminate material property definition. Table 1 below shows that the chosen honeycomb core...
2.0 MB	ST7-1.40.50.6 Aligning Orthotropic Brick Axes This Webnote introduces the method of aligning brick axes in Strand7. Brick axis alignment is essential for orthotropic material definition as well as for the extraction of results in the material axes. It is also convenient for the extraction of results in other coordinate systems, even for isotropic materials.
0.8 MB	ST7-1.40.50.7 Composite Results This Webnote summarises the conventions used by Strand7 for defining a laminate type plate element, and reviews the result quantities available for laminate plates. A laminate is defined as a stack of distinct layers of (usually) orthotropic material (the plies). With reference to the plate element local axes, each ply can be orientated independently of the other plies in the stack. In Strand7, the plate element local axes are denoted as the x-y axes, and the ply material (principal) axes...
ST7-1.40.60 Applications / Bridges
2.0 MB	ST7-1.40.60.1 Footfall Analysis of Low Frequency Vibration Sensitive Structures When pedestrians walk on floors, staircases, walkways and other such structures the dynamic load applied by their footfalls can induce vibrations. In this Webnote we present an approach to footfall analysis using the Strand7 harmonic response solver. The method includes the effect of walking at a given frequency exciting higher harmonics, and returns the following design results: Dynamic deflection; Vertical acceleration; and Human Response Factor.
2.1 MB	ST7-1.40.60.3 Precast Girders with an In-Situ Cast Deck Combining pre-cast and in-situ cast components in bridge design is complex. The bridge geometry is shown at right. The bridge span is angled and consists of two longitudinal steel girders with periodic internal reinforcement and a concrete deck. The span is about 16.5 m and the deck width is 9 m. The deck is constructed by first laying transverse pre-cast 80 mm thick transverse girders, then performing an in-situ cast on top of them. The pre-cast concrete transverse girders do not contribute...
1.7 MB	ST7-1.40.60.4 Cast Concrete Bridge Deck Creep and Shrinkage The consideration of creep and shrinkage effects can have a significant impact when analysing concrete structure which has in-situ cast components. To consider the creep and shrinkage behaviour of the deck (such as age at first loading), some changes need to be made to the original model.
1.5 MB	ST7-1.40.60.5 Bridge Load Influence Combinations There are two basic approaches to moving load analysis: load influence analysis and transient analysis. This Webnote covers load influence analysis. The first step in moving load analysis is defining a load path. Load paths in Strand7 can be straight, curved, or parabolic, and can have out-of-plane curvature as well. The load path definition includes the path geometry, number of divisions along the length, the element types it should apportion the load to, and a Load Path Template which defines the lanes and vehicles, and their interaction on the path.
3.9 MB	ST7-1.40.60.6 Bridge Moving Load Analysis with Creep and Shrinkage This Webnote outlines how to consider creep and shrinkage effects as initial conditions for a moving load analysis. A pair of M1 Abrams tanks are driven over a bridge which has concrete members which have cured for about 11 years (4000 days). This analysis follows on from ST7-1.40.60.4 Cast Concrete Bridge Deck Creep and Shrinkage. Note that the complex initial conditions presented here are not necessary for general moving load analysis. One use of the moving load module is to model an overloaded...
1.2 MB	ST7-1.40.60.9 Applying AS 5100.2 Moving Load This Webnote is relevant to the library Load Path Templates that are installed with Strand7 R245. It is explained in this document how to calculate the worst case live loads in Strand7 for AS 5100.22004, Bridge design, Part 2: Design loads insofar as this design code applies to road and highway bridges, and the traffic live load to which such structures are to be subjected. This design code makes use of the following terms and symbology, which shall be used in the same way for this section....
1.2 MB	ST7-1.40.60.10 Applying EN 1991-2 Moving Load This Webnote is relevant to the library Load Path Templates that are installed with Strand7 R245. It explains how to calculate the worst case live loads in Strand7 for EN 1991-2: 2003, Section 4: Road traffic actions and other actions specifically for road bridges insofar as this code applies to road and highway bridges, and the traffic live load to which such structures are to be subjected. This code makes use of the following terms and symbology, which shall be used in the same way for...
1.3 MB	ST7-1.40.60.11 Applying BS 5400-2 Moving Load This Webnote is relevant to the library Load Path Templates that are installed with Strand7 R245. It explains how to calculate the worst case live loads in Strand7 for BS 5400-2: 2006, Steel, concrete and composite bridges Part 2: Specification for loads insofar as this code applies to road and highway bridges, and the traffic live load to which such structures are to be subjected. This code makes use of the following terms and symbology, which shall be used in the same way for this section....
1.2 MB	ST7-1.40.60.12 Applying AASHTO-LRFD Moving Load This Webnote is relevant to the library Load Path Templates that are installed with Strand7 R245. It explains how to calculate the worst case live loads in Strand7 for AASHTO Load-and-resistance factor design Bridge Design Specifications, Article 3.6: 2004, Live Loads (hereafter AASHTO LRFD-BDS). insofar as this design code applies to road and highway bridges, and the traffic live load to which such structures are to be subjected. This design code makes use of the following terms and symbology,...
1.1 MB	ST7-1.40.60.18 Masonry Arch Bridge 2D Analysis Masonry arch construction relies on compressive loading in the arch to support load. Masonry material is orthotropic (having different properties in each direction) and cracks can form either along grout lines or through discrete bricks. This analysis addresses the questions what is the limit load of the structure? and where is cracking likely to start? We start with a 2D model and extend it to a 3D brick model as a comparison approach in the subsequent Webnote ST7-1.40.60.19 Masonry Arch...
ST7-1.40.70 Applications / Automotive
6.9 MB	ST7-1.40.70.1 Vehicle Suspension Static Stiffness An automotive suspension model is introduced and used to determine the static stiffness of the system as it responds to various operational loads. The nonlinear static solver is used to characterise the static response of the vehicle. The dynamic response of the vehicle is discussed in ST7-1.40.70.2 Vehicle Suspension Dynamic Stiffness. The provided initial model (ST7-1.40.70.1 Car Body and Suspension (0. Initial).st7) is a basic model of a car. The suspension is independent double-wishbone...
5.1 MB	ST7-1.40.70.8 Tuning an Exhaust System with Harmonic Analysis Automotive exhaust systems play a large role in the comfort of a vehicle. The example geometry is based on a typical mid-size car exhaust system fitted to a V8 engine. It has two symmetric, centrally linked exhaust pipes. Each has a catalytic converter, a resonator and a muffler. Several mount points are defined. Damping is also a critical parameter. The exhaust system is forced by pressure pulses and by direct engine vibration at the front. The vibration analysis will cover the operational...
1.1 MB	ST7-1.40.70.11 Analysis of a Rubber Exhaust Hanger and Grommet Exhaust systems are prone to vibration and are typically isolated from supporting structure by compliant rubberised components. Detailed models of these components are not practical in larger analyses, so it is important to estimate the stiffness to be modelled using simplified methods, such as beam elements or nodal stiffness attributes. In this analysis we investigate the stiffness of two common rubber isolator components for use in a larger model found in ST7-1.40.70.8 Tuning an Exhaust System...
15.2 MB	ST7-1.40.70.12 Automeshing and Analysis of a Cargo Frame Assembly This Webnote presents the automeshing and analysis of a cargo frame assembly. It summarises how Strand7 can be used to conduct FEA on a typical welded steel structure by highlighting various features and tools and concluding with the example. If solid CAD geometry is available then a brick model can be created easily for quick analysis. Strand7 is units aware. Units can also be changed at any stage during the modelling process, with the user choosing to scale or not scale the model according...
12.6 MB	ST7-1.40.70.15 Engine Head Gasket Analysis The head gasket in an internal combustion engine is a critical engine component. It seals the high pressures of the combustion chamber between the head and block. Typical automotive head gaskets are multi-layered steel gaskets which are clamped by the force of the head bolts. We can use contact elements to determine how much combustion pressure a given design can take before the gasket separates, allowing leakage. The included solid geometry is a section of a BMW M20 6-cylinder engine head....
1.2 MB	ST7-1.40.70.16 Motorcycle Engine Vibration Analysis Vibration is an unwanted side effect of reciprocating mass common to most discrete cycle machines, including internal combustion engines. In the case of a conventional piston engine, the reciprocating mass of the piston, connecting rod (conrod), wrist pin (gudgeon pin) and a little oil, all contribute to vibration. Designs are tailored to minimise vibrations as much as possible for a variety of reasons, of which the most important are user comfort and machine life. This Webnote covers the balancing...
7.8 MB	ST7-1.40.70.17 Multi-Cylinder Engine Vibration Analysis Vibration from multi-cylinder engines can be modelled in Strand7 by using the Harmonic Response solver. This Webnote is a continuation of ST7-1.40.70.16 Motorcycle Engine Vibration Analysis, which develops the basic loading from a single cylinder reciprocating engine. These methods are applied to a V8 engine to determine the response of the surrounding structure to the engine vibration.
3.8 MB	ST7-1.40.70.20 Thermal Analysis of a Disk Brake Rotor Disk brake design and performance is heavily tied to the temperatures generated by friction at the surface of the brake rotor. This situation can be modelled in Strand7 using the Moving Load Module. In this Webnote we apply a moving thermal load to the surface of a motorcycle brake rotor.
1.1 MB	ST7-1.40.70.22 Guard Rail Impact Analysis Guard rails must be designed to withstand impact from vehicles travelling at high speed. In this Webnote we explore modelling methods that can be used to simulate an impacting mass (820 kg) with initial velocity (100 kph) as it strikes a typical W-section guard rail at 20 degrees from parallel. A simple beam model is constructed.
1.2 MB	ST7-1.40.70.23 Plate Mesh Approach to Guard Rail Impact This Webnote is a continuation of ST7-1.40.70.22 Guard Rail Impact Analysis, in which a guard rail model using beam elements was impacted. In this analysis, we convert a portion of the guard rail into plate elements in order to consider crushing of the W-beam cross-section. The Head Injury Criterion (HIC) is calculated using the acceleration time history of the impactor. As in the previous analysis, an 820 kg mass travelling at 100 kph impacts the rail at 20 degrees.
7.5 MB	ST7-1.40.70.27 ROPS Analysis per ISO 3471-2008 Protection of the operator of earth moving equipment is required in circumstances where vehicle rollover is possible. This Webnote demonstrates the simulation of a Roll-Over Protective Structure (ROPS) physical test according to ISO 3471:2008. There are multiple types or classifications of ROPS; in this Webnote a multi-post ROPS typical of that seen on a backhoe digger is analysed.
ST7-1.40.80 Applications / Mining and Energy
1.3 MB	ST7-1.40.80.2 Meshing a Loader Bin with Reinforcing Ribs The basic surface geometry of the bin is shown at right and below. It is a tessellated welded assembly with reinforcing ribs which have not been explicitly modelled in CAD. This Webnote outlines how to add rib reinforcement features to a Strand7 model without returning to CAD, by using beam elements along lines of intended reinforcement. The geometry above is missing some definition of hoop ribs as well as ribs which run along the seams of the tesselated surfaces. Create a new model with...
ST7-1.40.90 Applications / Consumer Goods
0.9 MB	ST7-1.40.90.6 Camera Housing Rubber Seal Contact Analysis Underwater cameras must be designed to be waterproof to a certain depth. Camera housings are designed with rubber seals which protect the camera from getting wet. Rubber seals in contact with several surfaces can be analysed in Strand7. In this Webnote, 2D CAD geometry of a seal and housing is imported and automeshed to produce a finite element model of the contact situation, which is critical to avoid leakage.
ST7-1.40.100 Applications / Rail
1.9 MB	ST7-1.40.100.2 Contact Analysis of a Wheel and Rail This topic investigates rail-wheel contact interaction with varying axle load. The Strand7 solution is compared to the analytical Hertzian contact solution.
ST7-1.40.110 Applications / Biomechanical
1.1 MB	ST7-1.40.110.4 Biological Contact Modelling Strand7 can be used to model biological structures. Skeletal structure is inherently multi-body and requires the use of contact elements to model interactions. This topic covers the application of contacts and cutoff bars to model actuating muscles. Starting with the notional geometry of a skull, mandible and bone shown below, we will define contact and muscles. We will first define the contact elements. These will be of type Zero Gap, meaning that they will have no effect until the two parts...
ST7-1.40.130 Applications / Acoustics
0.8 MB	ST7-1.40.130.1 Calculating and Analysing Acoustic Cavity Modes Acoustically induced vibrations caused by the interaction between structural and an acoustic resonance (e.g. vibration of a pipe that contains an acoustic medium) can potentially lead to fatigue damage. For this reason it is important to analyse and understand the acoustic modes of such a system. This Webnote presents a step by step process for analysing an acoustic cavity.
0.9 MB	ST7-1.40.130.5 Acoustic Cavity Modes with Flexible Boundaries The acoustic cavity modes described in ST7-1.40.130.1 Calculating and Analysing Acoustic Cavity Modes are calculated under the assumption that the walls of the cavity are rigid. For a cavity with very thin walls, it is possible to get a strong interaction between the wall vibrations and the acoustic resonance inside the cavity. This Webnote presents the analysis of an acoustic cavity, which is coupled to a flexible wall.

1.2 MB

ST7-1.40.10.1 Autofrettage of a Composite-Metallic Tank
This document is intended as a demonstration of how Strand7 can be used to model and solve non-linear material problems in axisymmetric structures. The use of axisymmetric and plate/shell elements is also covered. Another tank model of interest is found in ST7-1.40.50.1 Modelling a Composite Tank. A composite pressure vessel with aluminium liner is subjected to an internal pressure intended to cause plastic deformation of the aluminium liner. In this demonstration a simplified representation...

1.1 MB

ST7-1.40.10.3 Analysis of Rocket Inertial Effects with Fuel and Payload
Rockets are capable of high-G manoeuvring, which enables them to take tighter turns than the targeted aircraft. When such a turn is entered, the structure is highly loaded by the inertia of the payload, structural mass and fuel mass. Strand7 can be used to model such an event by using the Inertia Relief solver, which produces analysis results for structure which is not restrained, such as aircraft, floating ships and rockets. Additionally, the consideration of a fuel payload can be distributed...

1.1 MB

ST7-1.40.10.7 Panel Buckling Analysis
A 1 m x 3 m stiffened aluminium panel is subjected to pressurised overloading to determine post-buckling behaviour. Five ribs and two hat stringers provide support to the skin.

1.8 MB

ST7-1.40.10.8 PSD Analysis of a Wing-Mounted Missile
A wing-mounted missile is subjected to the severe vibrational environment of a performance fighter wing. This analysis outlines how to load a rocket using a power spectral density curve and Strand7s spectral response solver. This analysis is based on data from the F-15B fighter, provided by NASA [1] . A Sidewinder missile model [2] will be used to investigate the response of the missile and contained propellant to the given vibrational environment. The goal of the analysis is to investigate...

3.1 MB

ST7-1.40.20.1 Strand7 and Marine Structures
Strand7 is a general-purpose structural finite element analysis package that has been developed to meet the requirements of practising engineers across all engineering disciplines including naval architecture. These notes summarise how Strand7 can be used to conduct FEA on a typical marine structure by highlighting various features and tools, concluding with an example. A typical frame in marine structures consists of thin panels and stiffeners. Material properties are defined by choosing...

0.5 MB

ST7-1.40.20.2 Underwater Cable - Catenary and Forces
Strand7 is equipped with cable elements which can be used to determine the catenary shape due to gravity, distributed loads and concentrated loads. This document shows an example of cable elements used to solve an underwater cable system. A 1000 m underwater cable consisting of metal chains and wire rope is shown below. Create a new SI unit model. Create a beam element joining nodes at (0,0,0) and (500,500,0). Use Tools/Split Beams with a 0.3 Split Ratio to divide the beam into two elements. ...

2.5 MB

ST7-1.40.20.3 Buoyancy and Stability Analysis of Floating Structures
Strand7 provides tools to model offshore floating structures such as boats subject to buoyant forces, payload and other loadings. A standard residential pontoon decking is supported by four 1200 L flotation modules. To determine the submerged level of the deck at steady state. To determine the displacement of the deck with a full payload. To observe the effect of ballast weight on stability. The model is set up as follows: The first step is to apply unit normal pressure to the pontoon...

1.5 MB

ST7-1.40.20.4 Transverse Stability of a Ship
This Webnote describes the techniques that can be used to determine the centre of gravity, centre of buoyancy, metacentre and rolling period of a ship, and produce its curve of statical stability. The results are then verified by a set of analytical solutions.

7.0 MB

ST7-1.40.20.5 Dynamic Impact Analysis of a Moored Ship
Buoyancy effects on marine structures can be analysed to determine the dynamic response of floating structures. In this Webnote we consider the effect of a strong wind on a moored tugboat. Contact is defined between the mooring dolphin and ship. Cable elements connect the ship to the dolphin.

0.5 MB

ST7-1.40.20.6 Sub-Sea Cable Tensioning Analysis
The catenary cable is a line element with a free length that can be different to the distance between the nodes to which it is connected. This allows the element to droop under the action of gravity or global accelerations. The string group attribute is a very powerful attribute that facilitates the modelling of cable or string-like connections, where a cable is connected to a node, but can freely slide through that node. It is analogous to the modelling of a frictionless pulley.

0.8 MB

ST7-1.40.20.7 Progressive Lift of a Weighted Mooring Line
The anchor of a 40' boat is set and the boat is subjected to wind load. The anchor rode consists of 5/8" three-strand Nylon and 5/16" Proof Coil steel chain (1.09 lb/ft). Some 5.0 lbs sinkers have been added to the chain to help keep the pull horizontal. The objective is to determine the required wind force on the boat to lift the chain off the seabed.

4.9 MB

ST7-1.40.30.2 Fluid-Structure Interaction Tank Sloshing Analysis
This document illustrates how to construct and analyse in Strand7, a model of an LNG (Liquefied Natural Gas) filled concrete tank resting on buried piles. Create a new Strand7 file. Choose SI units. Choose Global/Coordinate Systems, Create a Cylindrical UCS of XY type at (0,0,0). This will create a cylindrical UCS, which will be referred to often throughout the modelling process. Create a set of nodes referenced to the cylindrical UCS: Choose View/Angles and change to a ZX Plane...

1.0 MB

ST7-1.40.30.3 Lateral Earth Pressure and Retaining Walls
Lateral earth pressure is one of the most important factors to be considered when designing retaining walls, or indeed, for designing any structure that interacts with soil. This Webnote demonstrates the application of Strand7 in the calculation of lateral earth pressure and analysis of retaining walls by using the nonlinear static solver.

0.5 MB

ST7-1.40.30.4 Cable Systems
Strand7 has the ability to model cable-pulley systems and catenary cables under gravity and applied loads. An example of a simplified elevated ski lift structure is demonstrated here. Create a new file and set the units to Nmm. Create a few vertical beams representing the cable support columns using Create/Element and Snap Grid or by entering node locations with Create/Node. Connect them with beam elements representing the cables. In the model shown at right, beam taper attributes...

0.7 MB

ST7-1.40.30.6 Dam-Soil Interaction Static and Dynamic Loading
Dams are complex structures which interact with the surrounding environment due to their massive size. This interaction is analysed using a simple dam model for a 1G static and El Centro earthquake dynamic conditions. The simple dam model is shown at right. It is a mildly arched dam sitting on fill between two rock walls. It was formed using manual meshing techniques including extrusion, copying and scaling by a cylindrical coordinate system to form the arch curvature. All nodes at interfaces...

1.1 MB

ST7-1.40.30.11 Construction Sequence Analysis of Tunnelling in Soils
Tunnelling and excavation are common practice in civil and geotechnical engineering, so prediction of the mechanical behaviour of soil and structure is very important for design. However, due to the complexity of soil conditions, such as groundwater level (or water table), in-situ stresses and void ratio etc., and the staged characteristics of tunnelling and excavation procedures, accurate prediction of soil-structure interaction is also very challenging. Strand7 provides a staged (construction...

0.9 MB

ST7-1.40.30.22 Analysis of Soil Slope Stability Using Strand7
Soil slope stability analysis is an important subject in civil engineering for the design of roads, railways, dams, and so on. This Webnote presents an example of using Strand7 to investigate soil slope stability and to find a critical state of a slope under a given condition.

2.0 MB

ST7-1.40.35.1 Glass Facade Blast Loading
Glass Facade construction is subject to blast loading requirements. These unique structures come in a variety of custom configurations suited to the particular needs of each installation. Due to the variability of each design, Finite Element Analysis can be a very powerful and cost-effective tool in the qualification of these structures. An example glass facade is shown at right. A joint detail is shown below, with the mounting hardware in green, and backing structure in orange and a post-tensioned...

1.1 MB

ST7-1.40.35.2 Extracting Resultant Forces and Moments from a Building
This Webnote explains how to extract actions from an entire building or portion of a building. Four related procedures are illustrated: Finding the centre of mass of a building (in plan). Finding the centre of stiffness (the shear centre) for a particular storey of a building. Using staging to analyse multiple scenarios in a single model. Finding the resultant actions on a particular storey of a building. The first two procedures are particularly useful in seismic analysis because...

1.3 MB

ST7-1.40.35.4 Modelling Timber as an Orthotropic Material
An orthotropic material is defined as having three mutually orthogonal axes. The structural response depends on the material's orientation with respect to the loading. Wood may be characterised as an orthotropic material...

1.4 MB

ST7-1.40.35.5 Reinforced Concrete Slab Ductility
Several methods to model reinforced concrete are discussed and compared using a typical 200 mm thick slab. The most detailed approach is to model the concrete with layers of brick elements and the reinforcing bars as beam elements embedded within. Other options include replacing the reinforcing beam elements with a smeared layer of plate mesh with equivalent cross-section area and/or replacing the concrete brick mesh with an equivalent plate mesh.

1.9 MB

ST7-1.40.35.6 Modelling Post Tensioned Concrete in Strand7
Given that Strand7 is a general purpose FEA package rather than a specialised prestressed concrete (PSC) design package, users may not be aware of the potential for Strand7 to analyse PSC structures. This document outlines one method for modelling a post-tensioned one-way slab (150mm thick) and transverse band beams (400mm deep) with discrete draped bonded tendons. In addition to self-weight and prestress, the slab will be subjected to a 1 kPa superimposed dead load and a 7.5 kPa live load. ...

1.9 MB

ST7-1.40.35.7 Kalzip Corrugated Roofing
Kalzip corrugated roofing is an aluminium sheet product used to build large, sometimes highly complex roofing and cladding structures. It is flexible enough to form attractive contours and is featured on well known architectural designs, such as Melbournes Southern Cross Station. Strand7 can be used to analyse design details under load and improve or verify existing designs. Kalzip features an interlocking design which simplifies installation. Kalzip provides DXF geometry of common...

0.8 MB

ST7-1.40.35.8 Modelling Tension-Only or Compression-Only Structural Members
Many structural members and connections have different tensile and compressive behaviour. Typical structural features which are compression-only include contact and bearing situations, whilst tension-only members often include bolts, bracing, cables, ropes or chains. Nonlinear analysis is generally required to consider such members, as it is often not known beforehand which members will be in tension and which members will be in compression, particularly in complex structures.

0.8 MB

ST7-1.40.35.11 Modelling Friction Pendulum Seismic Isolation Bearings
Friction Pendulums seismic isolators are used for isolating earthquake movements from the buildings they support, thus protecting the buildings from earthquake damage. These bearings also dissipate energy associated with relative movement between the building and the ground by their hysteretic behaviour. Typical response of a single isolator is schematically illustrated on the right where FL and DL are the lateral force and displacement, respectively. The stiffness associated with slippage (step...

1.2 MB

ST7-1.40.35.13 Analysis of Blast Resistant Structures
The design of blast resistant structure in hostile environments has previously been limited to nonlinear single degree of freedom (SDOF) approximations, which limits the analysis to point-wise design checking of individual members. This Webnote will draw on the experience of blast loading developed in UFC 3-340-02[1] and apply it to a nonlinear transient blast analysis using Strand7. The example problem, Example 2A-10 found in [1], is replicated using FEA. The resulting acceleration, velocity...

0.4 MB

ST7-1.40.35.14 Modelling Nonlinear Behaviour of Steel Reinforced Concrete
Steel reinforced concrete beams and columns are composite structures consisting of two very different materials. Steel has high stiffness and yield in both tension and compression whereas concrete has little strength in tension (cracks under tension). These different nonlinear material behaviours can be captured using different material models and stress-strain curves in Strand7. In the modelling sense, steel reinforced concrete beams and columns can be modelled in a variety of ways including: ...

1.4 MB

ST7-1.40.35.15 Extracting Shear Wall Design Action Effects
This Webnote describes a simple method for extracting the design action effects to be used for the design of shear walls. In order to provide a thorough explanation of the method, four models will be discussed: Consider the shear wall subjected to three lateral point loads shown opposite. The wall is fixed at the base, and grouped into three levels, each 4m in height. The wall is idealised as a cantilever beam and the shear forces and bending moments are calculated as shown on the following...

1.7 MB

ST7-1.40.35.22 AS 1170.4-2007 Earthquake Analysis in Strand7
This Webnote introduces Strand7 functionality that can be used in an earthquake analysis of a structure in accordance with AS1170.4-2007, the Australian Standard for earthquake action. The design code covers three main forms of analysis, namely Equivalent Static, Modal Response Spectrum, and Time History analysis.

0.8 MB

ST7-1.40.35.27 Tapered Circular Steel Towers
Tapered steel towers are common due to simplicity and low cost. These towers are sometimes faceted, but often circular in cross-section. This Webnote covers the basic modelling of a tapered circular tower, comparing a plate mesh with a tapered beam element approach. The structure is a simple tower which tapers from 2 m diameter at the bottom to 1 m diameter at the top. Thickness is a constant 10 mm. The model geometry is most easily generated by drawing the axisymmetric cross-section...

1.1 MB

ST7-1.40.35.32 Column Interaction Diagrams
This Webnote outlines procedures to create Moment vs Axial Force and Moment vs Curvature diagrams. A rectangular hollow section is studied. The example follows the European Code EC2 design assumptions, but the procedure is similar for other codes. Choose File/New and create a new model with units of Nmm. Choose Create/Node to create nodes at the following positions: (X=0; Y=0; Z=0); (X=1000; Y=0; Z=0); (X=0; Y=1500; Z=0); (X=1000; Y=1500; Z=0). Choose Create/Element, set Quad4 as...

1.0 MB

ST7-1.40.35.36 Cable Net Analysis
This Webnote describes a simple analysis of a 3D cable structure in Strand7 using the Nonlinear Static and Nonlinear Transient Dynamic solvers. All flexible members such as cables and wires in this type of structure can be modelled as Truss elements. These are axial force elements and do not provide lateral stiffness unless there is some tensile force in them. Therefore a pre-load attribute is usually applied to provide some lateral stiffness and assist solver convergence. Given the inherent...

0.5 MB

ST7-1.40.35.48 Precast Slab Lifting Analysis with String Groups
Precast slabs or walls are often lifted into place by crane and straps. In this analysis we model the lifting situation in which there are three pulleys arranged in a load-sharing scheme similar to a whiffle tree. Three independent cables support the panel, each with a pulley at the top. The model is a simple 2D beam model, although more complex 3D scenarios could also be modelled. The goal of this Webnote is to show how string groups work to model pulleys, and to evaluate the proposed lifting...

1.3 MB

ST7-1.40.35.49 Modelling Bond Slip in Reinforced Concrete
Tensile stress is generated in steel reinforcing bars via shear stress at the interface between the concrete and reinforcement. This shear stress is referred to as bond stress. If the bond stress exceeds the local shear capacity at the interface, the bar may slip relative to the concrete. This Webnote examines the implementation of a nonlinear bond stress vs slip relationship in Strand7.

2.2 MB

ST7-1.40.40.1 Fatigue Analysis of a Welded Connection
Many structures are subjected to cyclical loads of relatively small magnitude but with a large number of cycles. Structures under this type of loading may be required to be analysed for fatigue endurance to determine their working life. There are many design standards that stipulate the fatigue requirements of various types of structures such as for pressure vessels (BS 5500, with newer versions referred to as PD 5500), steel, concrete and composite bridges (BS 5400, AASHTO LRFD Section 6.6), and steel structures (BS 7608, BS EN 1993-1-9:2005, AS 4100). The methods of analysis outlined in this Webnote use terminology and notation consistent with BS 7608, BS 5500 and EN 1993-1-9, but aim to be general enough to be applied to other fatigue design codes.

1.1 MB

ST7-1.40.40.3 Analysis of a Welded Clip
A welded clip is fabricated to join two parts in transit. The clip consists of two angles welded along two connecting seams. The two angles are shown in red and blue at right, with green fillet welds. The blue angle has slotted holes to avoid overloading in the vertical direction. The clip will be modelled using shell elements, rigid links and contact elements. The supporting structure behind the clip will be represented by compression-only face support attributes. Shell models are...

0.8 MB

ST7-1.40.40.4 Analysis of Pressure Vessels using AS1210 - 1997
AS 1210 1997 Appendix B concerns the application of FEA to the design of pressure vessels. A few key points and how to apply them to Strand7 are paraphrased (in italics) and addressed below. FEA should only be used alongside traditional techniques. FEA is a complex analysis technique which shouldnt be relied upon in isolation if alternative methods of analysis and/or testing are available. Linear static analysis is the most typical type of FE analysis. Strand7 allows for the contouring...

1.9 MB

ST7-1.40.40.6 Modelling Hydraulic Actuation
This Webnote is a continuation of the automeshing Webnote ST7-1.50.10.2 Surface Automeshing an Excavator Assembly. In this continuation, we apply hydraulic actuators to force the digger arm mechanism through the range of motion. We will use stiff truss elements with pre-strain attributes which, when scaled, produce an actuating effect through contraction and expansion. There are three lugs which are pivots between parts in the assembly, and five lugs which connect hydraulic actuators between...

0.8 MB

ST7-1.40.40.8 Extensional Behaviour of Pressurised Curved Pipes
Curved pipes with non-circular cross-sections tend to straighten when pressurised, as the cross-sectional profile tries to stretch into a circle. Curved pipes with a perfectly circular cross-section do not experience this phenomenon. However, curved pipes are often developed by a rolling-forming operation which leaves the cross-section slightly non-circular. This in turn can lead to extensional effects in formed piping. Create a new model with Nmm units. Activate the snap grid, and set...

1.1 MB

ST7-1.40.40.22 Applying Pad Eye Loads
This Webnote illustrates some common techniques to apply loading to a pad eye modelled with plates and bricks. We will look at several configurations to apply a force of approximately 1.4 kN to the pad eye: Rigid Connection Multi-Point Link Contact Elements Uneven Load Distribution with Bolt Pressure Distribution To create rigid connection, use Tools/Auto Assign/Restraints/Rigid Connections and then apply appropriate loading to the master node. Pros Can be used in both...

6.2 MB

ST7-1.40.40.23 Foundation Vibration Analysis
The vibration of foundations supporting machinery must be checked to prevent damage to the machinery and connected structure. The Harmonic Response Solver can be used to do this. A code focused approach is taken based on ISO 10816 and DIN 4024. The model is built from CAD geometry and modified as necessary. The attached machinery vibrates due to out of balance rotating mass caused by tolerances and the large rotating masses involved in typical industrial machinery. We will define the...

3.0 MB

ST7-1.40.40.27 Modelling Interference Fits by Using Shrink Links
Interference fits (shrink fits, or press fits) are commonly used in mechanical engineering for various purposes, such as holding parts together, transferring power or load, and introducing compressive stresses in parts. In this Webnote, we use Shrink links to analyse interference fits in various situations.

3.5 MB

ST7-1.40.40.28 Modelling Interference Fits by Using Contact Elements
Interference fits (shrink fits, or press fits) are commonly used in mechanical engineering for various purposes, such as holding parts together, transferring power or load, and introducing compressive stresses in parts. In this Webnote, we use contact elements to analyse interference fits in various situations.

0.7 MB

ST7-1.40.40.33 Press Fit Shaft Extension Torsional Analysis
A shaft is to be extended with a press fit interface. The torsion capability of the new joint is explored by using contact elements with friction. The shaft extension is heated and the contact elements are placed between the two parts, such that when it is cooled a pre-load is generated in the contact elements. This radial load then creates friction in the joint when a torque is applied.

4.0 MB

ST7-1.40.50.1 Modelling a Composite Tank
The analysis of composite structures is more complex than metallic structures because it requires the definition of ply properties, laminate stacks and element directions. The tank geometry is shown below. The tank body is filament wound, with 5mm stainless steel reinforced penetrations. It is fitted into a stainless steel support collar. Six lifting lugs are provided. This CAD geometry is imported into Strand7 using the IGES format. The tank is composed of filament-wound VTM266-1 700gsm...

1.2 MB

ST7-1.40.50.2 Modelling a Composite Bracket
Thick curved composite parts prove challenging to design, analyse and manufacture due to the orthotropic properties of the constituent plies. A 10 mm thick three-tab CFRP bracket is shown below. At left, the thick CAD solid part is shown. At middle, the equivalent mid-surface geometry is shown. This is used to generate a surface automesh of plate elements (shown at right) which has a laminate property definition applied. Approximate model size is 100 mm. / / / The bolt pattern...

2.2 MB

ST7-1.40.50.3 Modelling a Composite Pultruded Rail
Pultrusion is a continuous composites manufacturing technique whereby fibre is pulled through a series of processing steps, resulting in a cured continuous shape. Pultrusion typically consists of a unidirectional fibre core, with the ability to add a continuous braid around the outside. In this example we will cover the stress analysis of a handrail subject to bending and external pressure loads. On half of the symmetric geometry of a pultruded composite stairway is shown below. The IGES geometry...

0.9 MB

ST7-1.40.50.4 Composites with Core
Laminate composites often employ a light-weight core to increase the section depth which increases the stiffness and strength in bending. Modelling core in Strand7 can be achieved in a few different ways we will cover the two most common methods in this document: as a ply definition and as a solid (brick) element between two plate elements. The simplest way to model core is to include it as a ply in the laminate material property definition. Table 1 below shows that the chosen honeycomb core...

2.0 MB

ST7-1.40.50.6 Aligning Orthotropic Brick Axes
This Webnote introduces the method of aligning brick axes in Strand7. Brick axis alignment is essential for orthotropic material definition as well as for the extraction of results in the material axes. It is also convenient for the extraction of results in other coordinate systems, even for isotropic materials.

0.8 MB

ST7-1.40.50.7 Composite Results
This Webnote summarises the conventions used by Strand7 for defining a laminate type plate element, and reviews the result quantities available for laminate plates. A laminate is defined as a stack of distinct layers of (usually) orthotropic material (the plies). With reference to the plate element local axes, each ply can be orientated independently of the other plies in the stack. In Strand7, the plate element local axes are denoted as the x-y axes, and the ply material (principal) axes...

2.0 MB

ST7-1.40.60.1 Footfall Analysis of Low Frequency Vibration Sensitive Structures
When pedestrians walk on floors, staircases, walkways and other such structures the dynamic load applied by their footfalls can induce vibrations. In this Webnote we present an approach to footfall analysis using the Strand7 harmonic response solver. The method includes the effect of walking at a given frequency exciting higher harmonics, and returns the following design results:

Dynamic deflection;
Vertical acceleration; and
Human Response Factor.

2.1 MB

ST7-1.40.60.3 Precast Girders with an In-Situ Cast Deck
Combining pre-cast and in-situ cast components in bridge design is complex. The bridge geometry is shown at right. The bridge span is angled and consists of two longitudinal steel girders with periodic internal reinforcement and a concrete deck. The span is about 16.5 m and the deck width is 9 m. The deck is constructed by first laying transverse pre-cast 80 mm thick transverse girders, then performing an in-situ cast on top of them. The pre-cast concrete transverse girders do not contribute...

1.7 MB

ST7-1.40.60.4 Cast Concrete Bridge Deck Creep and Shrinkage
The consideration of creep and shrinkage effects can have a significant impact when analysing concrete structure which has in-situ cast components. To consider the creep and shrinkage behaviour of the deck (such as age at first loading), some changes need to be made to the original model.

1.5 MB

ST7-1.40.60.5 Bridge Load Influence Combinations
There are two basic approaches to moving load analysis: load influence analysis and transient analysis. This Webnote covers load influence analysis. The first step in moving load analysis is defining a load path. Load paths in Strand7 can be straight, curved, or parabolic, and can have out-of-plane curvature as well. The load path definition includes the path geometry, number of divisions along the length, the element types it should apportion the load to, and a Load Path Template which defines the lanes and vehicles, and their interaction on the path.

3.9 MB

ST7-1.40.60.6 Bridge Moving Load Analysis with Creep and Shrinkage
This Webnote outlines how to consider creep and shrinkage effects as initial conditions for a moving load analysis. A pair of M1 Abrams tanks are driven over a bridge which has concrete members which have cured for about 11 years (4000 days). This analysis follows on from ST7-1.40.60.4 Cast Concrete Bridge Deck Creep and Shrinkage. Note that the complex initial conditions presented here are not necessary for general moving load analysis. One use of the moving load module is to model an overloaded...

1.2 MB

ST7-1.40.60.9 Applying AS 5100.2 Moving Load
This Webnote is relevant to the library Load Path Templates that are installed with Strand7 R245. It is explained in this document how to calculate the worst case live loads in Strand7 for AS 5100.22004, Bridge design, Part 2: Design loads insofar as this design code applies to road and highway bridges, and the traffic live load to which such structures are to be subjected. This design code makes use of the following terms and symbology, which shall be used in the same way for this section....

1.2 MB

ST7-1.40.60.10 Applying EN 1991-2 Moving Load
This Webnote is relevant to the library Load Path Templates that are installed with Strand7 R245. It explains how to calculate the worst case live loads in Strand7 for EN 1991-2: 2003, Section 4: Road traffic actions and other actions specifically for road bridges insofar as this code applies to road and highway bridges, and the traffic live load to which such structures are to be subjected. This code makes use of the following terms and symbology, which shall be used in the same way for...

1.3 MB

ST7-1.40.60.11 Applying BS 5400-2 Moving Load
This Webnote is relevant to the library Load Path Templates that are installed with Strand7 R245. It explains how to calculate the worst case live loads in Strand7 for BS 5400-2: 2006, Steel, concrete and composite bridges Part 2: Specification for loads insofar as this code applies to road and highway bridges, and the traffic live load to which such structures are to be subjected. This code makes use of the following terms and symbology, which shall be used in the same way for this section....

1.2 MB

ST7-1.40.60.12 Applying AASHTO-LRFD Moving Load
This Webnote is relevant to the library Load Path Templates that are installed with Strand7 R245. It explains how to calculate the worst case live loads in Strand7 for AASHTO Load-and-resistance factor design Bridge Design Specifications, Article 3.6: 2004, Live Loads (hereafter AASHTO LRFD-BDS). insofar as this design code applies to road and highway bridges, and the traffic live load to which such structures are to be subjected. This design code makes use of the following terms and symbology,...

1.1 MB

ST7-1.40.60.18 Masonry Arch Bridge 2D Analysis
Masonry arch construction relies on compressive loading in the arch to support load. Masonry material is orthotropic (having different properties in each direction) and cracks can form either along grout lines or through discrete bricks. This analysis addresses the questions what is the limit load of the structure? and where is cracking likely to start? We start with a 2D model and extend it to a 3D brick model as a comparison approach in the subsequent Webnote ST7-1.40.60.19 Masonry Arch...

6.9 MB

ST7-1.40.70.1 Vehicle Suspension Static Stiffness
An automotive suspension model is introduced and used to determine the static stiffness of the system as it responds to various operational loads. The nonlinear static solver is used to characterise the static response of the vehicle. The dynamic response of the vehicle is discussed in ST7-1.40.70.2 Vehicle Suspension Dynamic Stiffness. The provided initial model (ST7-1.40.70.1 Car Body and Suspension (0. Initial).st7) is a basic model of a car. The suspension is independent double-wishbone...

5.1 MB

ST7-1.40.70.8 Tuning an Exhaust System with Harmonic Analysis
Automotive exhaust systems play a large role in the comfort of a vehicle. The example geometry is based on a typical mid-size car exhaust system fitted to a V8 engine. It has two symmetric, centrally linked exhaust pipes. Each has a catalytic converter, a resonator and a muffler. Several mount points are defined. Damping is also a critical parameter. The exhaust system is forced by pressure pulses and by direct engine vibration at the front. The vibration analysis will cover the operational...

1.1 MB

ST7-1.40.70.11 Analysis of a Rubber Exhaust Hanger and Grommet
Exhaust systems are prone to vibration and are typically isolated from supporting structure by compliant rubberised components. Detailed models of these components are not practical in larger analyses, so it is important to estimate the stiffness to be modelled using simplified methods, such as beam elements or nodal stiffness attributes. In this analysis we investigate the stiffness of two common rubber isolator components for use in a larger model found in ST7-1.40.70.8 Tuning an Exhaust System...

15.2 MB

ST7-1.40.70.12 Automeshing and Analysis of a Cargo Frame Assembly
This Webnote presents the automeshing and analysis of a cargo frame assembly. It summarises how Strand7 can be used to conduct FEA on a typical welded steel structure by highlighting various features and tools and concluding with the example. If solid CAD geometry is available then a brick model can be created easily for quick analysis. Strand7 is units aware. Units can also be changed at any stage during the modelling process, with the user choosing to scale or not scale the model according...

12.6 MB

ST7-1.40.70.15 Engine Head Gasket Analysis
The head gasket in an internal combustion engine is a critical engine component. It seals the high pressures of the combustion chamber between the head and block. Typical automotive head gaskets are multi-layered steel gaskets which are clamped by the force of the head bolts. We can use contact elements to determine how much combustion pressure a given design can take before the gasket separates, allowing leakage. The included solid geometry is a section of a BMW M20 6-cylinder engine head....

1.2 MB

ST7-1.40.70.16 Motorcycle Engine Vibration Analysis
Vibration is an unwanted side effect of reciprocating mass common to most discrete cycle machines, including internal combustion engines. In the case of a conventional piston engine, the reciprocating mass of the piston, connecting rod (conrod), wrist pin (gudgeon pin) and a little oil, all contribute to vibration. Designs are tailored to minimise vibrations as much as possible for a variety of reasons, of which the most important are user comfort and machine life. This Webnote covers the balancing...

7.8 MB

ST7-1.40.70.17 Multi-Cylinder Engine Vibration Analysis
Vibration from multi-cylinder engines can be modelled in Strand7 by using the Harmonic Response solver. This Webnote is a continuation of ST7-1.40.70.16 Motorcycle Engine Vibration Analysis, which develops the basic loading from a single cylinder reciprocating engine. These methods are applied to a V8 engine to determine the response of the surrounding structure to the engine vibration.

3.8 MB

ST7-1.40.70.20 Thermal Analysis of a Disk Brake Rotor
Disk brake design and performance is heavily tied to the temperatures generated by friction at the surface of the brake rotor. This situation can be modelled in Strand7 using the Moving Load Module. In this Webnote we apply a moving thermal load to the surface of a motorcycle brake rotor.

1.1 MB

ST7-1.40.70.22 Guard Rail Impact Analysis
Guard rails must be designed to withstand impact from vehicles travelling at high speed. In this Webnote we explore modelling methods that can be used to simulate an impacting mass (820 kg) with initial velocity (100 kph) as it strikes a typical W-section guard rail at 20 degrees from parallel. A simple beam model is constructed.

1.2 MB

ST7-1.40.70.23 Plate Mesh Approach to Guard Rail Impact
This Webnote is a continuation of ST7-1.40.70.22 Guard Rail Impact Analysis, in which a guard rail model using beam elements was impacted. In this analysis, we convert a portion of the guard rail into plate elements in order to consider crushing of the W-beam cross-section. The Head Injury Criterion (HIC) is calculated using the acceleration time history of the impactor. As in the previous analysis, an 820 kg mass travelling at 100 kph impacts the rail at 20 degrees.

7.5 MB

ST7-1.40.70.27 ROPS Analysis per ISO 3471-2008
Protection of the operator of earth moving equipment is required in circumstances where vehicle rollover is possible. This Webnote demonstrates the simulation of a Roll-Over Protective Structure (ROPS) physical test according to ISO 3471:2008. There are multiple types or classifications of ROPS; in this Webnote a multi-post ROPS typical of that seen on a backhoe digger is analysed.

1.3 MB

ST7-1.40.80.2 Meshing a Loader Bin with Reinforcing Ribs
The basic surface geometry of the bin is shown at right and below. It is a tessellated welded assembly with reinforcing ribs which have not been explicitly modelled in CAD. This Webnote outlines how to add rib reinforcement features to a Strand7 model without returning to CAD, by using beam elements along lines of intended reinforcement. The geometry above is missing some definition of hoop ribs as well as ribs which run along the seams of the tesselated surfaces. Create a new model with...

0.9 MB

ST7-1.40.90.6 Camera Housing Rubber Seal Contact Analysis
Underwater cameras must be designed to be waterproof to a certain depth. Camera housings are designed with rubber seals which protect the camera from getting wet. Rubber seals in contact with several surfaces can be analysed in Strand7. In this Webnote, 2D CAD geometry of a seal and housing is imported and automeshed to produce a finite element model of the contact situation, which is critical to avoid leakage.

1.9 MB

ST7-1.40.100.2 Contact Analysis of a Wheel and Rail
This topic investigates rail-wheel contact interaction with varying axle load. The Strand7 solution is compared to the analytical Hertzian contact solution.

1.1 MB

ST7-1.40.110.4 Biological Contact Modelling
Strand7 can be used to model biological structures. Skeletal structure is inherently multi-body and requires the use of contact elements to model interactions. This topic covers the application of contacts and cutoff bars to model actuating muscles. Starting with the notional geometry of a skull, mandible and bone shown below, we will define contact and muscles. We will first define the contact elements. These will be of type Zero Gap, meaning that they will have no effect until the two parts...

0.8 MB

ST7-1.40.130.1 Calculating and Analysing Acoustic Cavity Modes
Acoustically induced vibrations caused by the interaction between structural and an acoustic resonance (e.g. vibration of a pipe that contains an acoustic medium) can potentially lead to fatigue damage. For this reason it is important to analyse and understand the acoustic modes of such a system. This Webnote presents a step by step process for analysing an acoustic cavity.

0.9 MB

ST7-1.40.130.5 Acoustic Cavity Modes with Flexible Boundaries
The acoustic cavity modes described in ST7-1.40.130.1 Calculating and Analysing Acoustic Cavity Modes are calculated under the assumption that the walls of the cavity are rigid. For a cavity with very thin walls, it is possible to get a strong interaction between the wall vibrations and the acoustic resonance inside the cavity. This Webnote presents the analysis of an acoustic cavity, which is coupled to a flexible wall.