# Copyright (c) 2019-2021 - for information on the respective copyright owner
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# https://github.com/boschresearch/pylife
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# Licensed under the Apache License, Version 2.0 (the "License");
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# http://www.apache.org/licenses/LICENSE-2.0
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__author__ = "Johannes Mueller"
__maintainer__ = __author__
import pandas as pd
import numpy as np
import scipy.stats as stats
from pylife.stress import stresssignal
from pylife.utils.functions import scatteringRange2std
[docs]@pd.api.extensions.register_dataframe_accessor('infinite_security')
class InfiniteSecurityAccessor(stresssignal.CyclicStressAccessor):
""" Compute Security factor for infinite cyclic stress.
"""
[docs] def factors(self, woehler_data, allowed_failure_probability):
"""compute security factor between strength and existing stress.
Parameters
----------
woehler_data : dict
strength_inf: double - value for the allowed infinite cyclic strength
strength_scatter: double - scattering of strength
allowed_failure_probability : double
Failure Probability we allow
Returns
-------
double
quotient of strength and existing stress
"""
wd = woehler_data
std_dev = scatteringRange2std(wd.strength_scatter)
allowed_stress = 10**stats.norm.ppf(allowed_failure_probability,
loc=np.log10(wd.strength_inf),
scale=std_dev)
factors = allowed_stress / self._obj.sigma_a
return pd.DataFrame({'security_factor': factors}, index=self._obj.index)