Assessing the capability of the Wilshire equations in predicting uniaxial creep curves: An application to Waspaloy

It is important to be able to predict creep strains in aeroengine so as to enable small punch disc test results to be related to uniaxial creep test results using finite element models. The capability of the Wilshire equation to interpolate creep curves was assessed using creep tests on Waspaloy. This assessment required modifying the Wilshire equation for time to strains so that the parameters of this equation could be predicted as a function of strain in a way that did not allow predicted creep curves to double back on themselves. An artificial neural network was used to achieve this. It was found that the modified model was capable of interpolating the shape and the end points of the experimental creep curves. These modifications enabled the activation energy to be measured and it was found that the activation energy is dependent upon the average internal stress and thus strain