Identification of Behavior of Linearly Viscoelastic Materials from Experiments on Relaxation with Initial Area of Increasing Strain

Resumo

The problem of the determination of the relaxation functions of linearly viscoelastic materials is studied in experiments with a double-step strain process (ramp test); strain increases at the first stage and is constant at the second stage. The experimental data on the dependency of stresses on time are analyzed in three ways with a subsequent comparison of results. The first method requires fulfillment of the 10 rule and uses the backward recurrence method; the second is based on the formulas of approximate integration. In the third, it is immediately assumed that the relaxation function can be represented by a truncated Prony series. For the Maxwell linear model, the 10 rule was analyzed analytically.