# stress_strain_life_parameters_from_data¶

class reliability.PoF.stress_strain_life_parameters_from_data(strain, stress, E, cycles=None, print_results=True, show_plot=True)

This function will use stress and strain data to calculate the stress-strain parameters: K, n. If cycles is provided it will also calculate the strain-life parameters: sigma_f, epsilon_f, b, c.

It is not posible to calculate the strain-life parameters without stress because stress is needed to find elastic strain.

If you already have the parameters K, n, sigma_f, epsilon_f, b, c, then you can use the function ‘stress_strain_diagram’ for the plot.

Parameters: strain (array, list) – The strain values stress (array, list) – The stress values E (int, float) – The modulus of elasticity. Ensure this is in the same units as stress (typically MPa). cycles (array, list, optional) – The number of cycles to failure. Optional input. This is required if you want to obtain the parameters sigma_f, epsilon_f, b, c print_results (bool, optional) – If True the results will be printed to console. Default is True. show_plot (bool, optional) – If True the stress strain diagram will be produced. Default is True. Use plt.show() to show it. K (float) – The cyclic strength coefficient n (float) – The cyclic strain hardening exponent sigma_f (float) – The fatigue strength coefficient. This is only generated if cycles is provided. epsilon_f (float) – The fatigue strain coefficient. This is only generated if cycles is provided. b (float) – The elastic strain exponent. This is only generated if cycles is provided. c (float) – The plastic strain exponent. This is only generated if cycles is provided.