Addendum to “relaxation and creep in twist and flexure”

Abstract

Purpose

In this addendum, the purpose of this paper is to introduce the new creep law for the description of the different stages of creep. The introduced creep law generalizes the creep law used in Kobelev (2014).

Design/methodology/approach

The new generalized creep law demonstrates the relationship between creep rate and stress as well as accounts the time dependence in different creep regimes. In the stage of primary creep there is explicit time dependence of creep rate. In the stage of secondary creep the creep rate exhibits – analogously to the original creep law – no explicit dependence on time.

Findings

The closed form expressions giving the torque and bending moment as a function of the time are provided. The method is applicable for definite other stress functions in the creep law.

Research limitations/implications

The arbitrary creep law allows the separation of time and spatial variables; exponential and power-law time dependence.

Practical implications

The results of creep simulation are applied to practically important problem of engineering, namely for simulation of creep and relaxation of helical and disk spring, driveshafts, torque elements of machine dynamics.

Originality/value

The new creep model with fractional derivative of time dependence is introduced. The closed form solutions for new creep model allow simple formulas for creep effect on stress and deformation and the implications for high temperature design.

Citation

Kobelev, V. (2016), "Addendum to “relaxation and creep in twist and flexure”", Multidiscipline Modeling in Materials and Structures, Vol. 12 No. 3, pp. 473-477. https://doi.org/10.1108/MMMS-10-2015-0065