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Defining Temperature Dependent Material Properties

• All of the linearised hardening gradients (Ep) for the material data must be less than (not equal to) the initial elastic modulus (E)
• All the temperature curves should have the same number of stress-strain coordinates defined
• All the strain values used with their corresponding stress values for each curve should be identical
• The difference between yield stress values for adjacent points on the same temperature curve should be as smooth as possible (i.e. not changing slope abruptly)
• Negative plastic strain "increments" must be avoided
• Ideally, curves that are basically identical throughout the whole strain range should be eliminated, e.g. in this case the curves at T=0 and T=20 are identical. This should not be a problem, but is a further possibility of small number problems when interpolating between "identical" curves
• The C (=Ep/(1 - Ep/E)) values become numerically large when Ep approaches E (they equal infinity when Ep=E). This can cause round-off problems and some inexplicable convergence problems/odd results. LUSAS converts the Ep values from the data input into corresponding C values for use throughout the analysis 

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