Creep: Primary + Secondary Power Law Creep

Description

Defines creep data parameters according to the primary and secondary power creep laws.

It has been found that considering the primary creep and secondary creep in separate but additive terms can accommodate an adequate representation of uniaxial creep curves.

Toolbar Functions

See LAYOUTS: Creep.

COEFFICIENTS

C₁ is the primary creep coefficient.

C₂ is the primary creep stress index.

C₃ is the primary creep time index.

C₄ is the secondary creep coefficient.

C₅ is the secondary creep stress index.

C_T1 is the primary creep temperature coefficient.

C_T2 is the secondary creep temperature coefficient.

PARAMETERS

Time Unit (t)

The unit of time in which the coefficients are specified.

Hardening

The creep hardening rule determines whether the creep strain rate is a function of the elapsed time or the amount of creep strain.

See Metal Creep: Hardening.

Time

With this rule, the creep strain rate is calculated based on the elapsed time.
Strain

With this rule, the creep strain rate is calculated based on the amount of creep strain in the model. Experimental evidence suggests that the strain hardening rule is to be favoured over the time hardening rule.

If Cyclic is set, extra auxiliary rules are used in conjunction with the strain hardening rule in order to better model stress reversal situations. Such modified strain hardening rule should be used for cyclic loading situations only.

Temperature

This option sets whether the creep law is dependent on temperature or not.

If set, the C_T parameter may be specified and the accumulation of creep strain is influenced by the nodal temperatures. The Property Temperature Dependence (see SOLVERS Home: Case Dependence tab) also needs to be assigned in the Quasi-static or Nonlinear Transient Dynamic solver to consider the creep temperature dependence.

If not set, the C_T parameter(s) is not used and the creep behaviour is independent of any applied nodal temperatures.