The RambergOsgood class

class pylife.materiallaws.RambergOsgood(E, K, n)

Simple implementation of the Ramberg-Osgood relation

Parameters:

• E (float) – Young’s Modulus
• K (float) – The strength coefficient
• n (float) – The strain hardening coefficient

Notes

The equation implemented is the one that Wikipedia refers to as “Alternative Formulation”. The parameters n and k in this are formulation are the Hollomon parameters.

delta_strain(delta_stress)

Calculate the cyclic Masing strain span for a given stress span

Parameters:delta_stress (array-like float) – The stress span Returns:delta_strain – The corresponding stress span Return type:array-like float Raises:ValueError if delta_stress is negative

Notes

A Masing like behavior is assumed for the material as described in Kerbgrundkonzept.

lower_hysteresis(stress, max_stress)

Calculate the lower (relaxation to compression) hysteresis starting from a given maximum stress

Parameters:

• stress (array-like float) – The stress (must be below the maximum stress)
• max_stress (float) – The maximum stress of the hysteresis look

Returns:

lower_hysteresis – The lower hysteresis branch from max_stress all the way to stress

Return type:

array-like float

Raises:

ValueError if stress > max_stress

plastic_strain(stress)

Calculate the plastic strain for a given stress

Parameters:stress (array-like float) – The stress Returns:strain – The resulting plastic strain Return type:array-like float Raises:ValueError if stress is negative

strain(stress)

Calculate the elastic plastic strain for a given stress

Parameters:stress (array-like float) – The stress Returns:strain – The resulting strain Return type:array-like float Raises:ValueError if stress is negative