Power Law
When the stress is below the tensile yield stress, the material behaves elastically. After yielding has occurred, the following graph may be used to represent the power law:
The equation that represents the relation between stress and strain for the power law is as follows:
σ = σy + Em (εp)m
where
• εp represents strain
• Em is the modified modulus
Modified modulus has the same units as Young's modulus. The value of the modified modulus is greater than 0 but less than Young’s modulus.
• m is the exponent
The exponent is a dimensionless quantity. The value of exponent for power law is greater than 0 but less than or equal to 1.
If you select Define By Tests then you must curve fit the values of Modified Modulus and Exponent. If you clear the Define By Tests check box, you must specify constants for Modified Modulus and Exponent.
