Materials: Orthotropic

Description

Orthotropic materials exhibits different material properties in each of three mutually orthogonal axes, the material axes. For linear analysis, the material can be characterised by the following parameters, with reference to the 1-2-3 material axes:

• - Young's moduli.
• - Shear moduli.
• - Poisson's ratios.
• - linear thermal expansion coefficient.
• - volumetric mass density.
• - thermal conductivity.
• - coefficient of specific heat.

Poisson's ratio, , is defined as a ratio between the normal strain components in the and directions when a uniaxial load is applied in the direction. That is,

and therefore the coefficients must satisfy the following relationships:

See the Straus7 Theoretical Manual for more information.

Example

For an orthotropic plane stress element, or an orthotropic plate/shell element, the in-plane material behaviour is defined in Straus7 with respect to the plate local x-y axes by the three coefficients and .

Assuming we have an orthotropic material with =35000 MPa, =5000 MPa, and =0.23, the data in the Straus7 property dialog can be entered in one of two equivalent ways, depending on the orientation of the plate local axes with respect to the material axes:

1. =35000 MPa, =5000 MPa, and =0.23; or
2. =5000 MPa, =35000 MPa, and =0.03286, where
   .

In the three dimensional case, all three directions needs to be considered in a similar way.

See Also

• Materials