The `likelihood` module

class pylife.materialdata.woehler.likelihood.Likelihood(fatigue_data)[source]

Calculate the likelihood a fatigue dataset matches with Wöhler curve parameters.

likelihood_finite(SD, k_1, ND, TN)[source]

likelihood_infinite(SD, TS)[source]

Produces the likelihood functions that are needed to compute the endurance limit and the scatter in load direction. The likelihood functions are represented by a cummalative distribution function. The likelihood function of a runout is 1-Li(fracture).

Parameters:

SD – Endurnace limit start value to be optimzed, unless the user fixed it.
TS – The scatter in load direction 1/TS to be optimzed, unless the user fixed it.

Returns:

Sum of the log likelihoods. The negative value is taken since optimizers in statistical packages usually work by minimizing the result of a function. Performing the maximum likelihood estimate of a function is the same as minimizing the negative log likelihood of the function.

Return type:

neg_sum_lolli

likelihood_total(SD, TS, k_1, ND, TN)[source]

Produces the likelihood functions that are needed to compute the parameters of the woehler curve. The likelihood functions are represented by probability and cummalative distribution functions. The likelihood function of a runout is 1-Li(fracture). The functions are added together, and the negative value is returned to the optimizer.