Applications of the Eyring equation to creep

Mindel and Brown [27] performed a Sherby-Dom type of analysis on data for the compressive creep of polycarbonate. Superposition was achieved using an equation of the form of Equation (10.30) with an activation volume of 5.7 nm, which was very close to the values of the activation volume obtained from measurements of the strain rate dependence of the yield stress (Section 11.5.1). 

The results suggest that creep rate can be represented by a general equation of the form 

We now replace the viscous strain rate ey with the high stress adaptation of Equation (11.32), which is 

Under conditions of stress relaxation, the total strain rate is zero, and the stress decays in a manner governed by the relation 

This can be solved by separation of variables to give the stress as 

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