The RambergOsgood class

class pylife.materiallaws.RambergOsgood(E, K, n)[source]

Simple implementation of the Ramberg-Osgood relation

Parameters:

  • E (float) – Young’s Modulus

  • K (float) – The strength coefficient, usually named K' or K_prime in FKM nonlinear related formulas.

  • n (float) – The strain hardening coefficient, usually named n' or n_prime in FKM nonlinear related formulas.

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.

property E

Get Young’s Modulus

property K

Get the strength coefficient

delta_strain(delta_stress)[source]

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 strain span

Return type:

array-like float

Notes

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

delta_stress(delta_strain)[source]

Calculate the cyclic Masing stress span for a given strain span

Parameters:

delta_strain (array-like float) – The strain span

Returns:

delta_stress – The corresponding stress span

Return type:

array-like float

Notes

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

elastic_strain(stress)[source]

Calculate the elastic strain for a given stress

Parameters:

stress (array-like float) – The stress

Returns:

strain – The resulting elastic strain

Return type:

array-like float

lower_hysteresis(stress, max_stress)[source]

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

property n

Get the strain hardening coefficient

plastic_strain(stress)[source]

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

strain(stress)[source]

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

stress(strain, *, rtol=1e-05, tol=1e-06)[source]

Calculate the stress for a given strain

Parameters:

strain (array-like float) – The strain

Returns:

stress – The resulting stress

Return type:

array-like float

tangential_compliance(stress)[source]

Calculate the derivative of the strain with respect to the stress for a given stress

Parameters:

stress (array-like float) – The stress

Returns:

dstrain – The resulting derivative

Return type:

array-like float

tangential_modulus(stress)[source]

Calculate the derivative of the stress with respect to the strain for a given stress

Parameters:

stress (array-like float) – The stress

Returns:

dstress – The resulting derivative

Return type:

array-like float