Adjustment Kriechzahl Prony Series

Fitting of the creep coefficient Prony series to the analytically determined creep coefficient using the least squares method

min_{α_{k}} \sum_{i = 1}^{m} {(φ (t_{i}) - φ_{∞} \sum_{k = 1}^{n} α_{k} (1 - e^{- t_{i} / τ_{k}}))}^{2}

αk	Weight factor (boundary conditions: greater than 0 and their sum must be 1)
i	Time Increments
m	Number of Time Increments
φ(ti)	Creep coefficient at time i
φ∞	Creep coefficient (infinite)
k	Current Element
n	Number of elements
e	Euler's number
ti	Time at time i
τk=ηk/Ek	Retardation time of the current element

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