Influence of prestrain on mechanical properties of highly-filled elastomers: Measurements and modeling

The influence of prestrain on viscoelastic properties |E∗| and tan δ of four different HTPB composite propellants was measured using Dynamic Mechanical Analysis (DMA). Nonlinear behaviour in terms of prestrain was observed and then modelled using a modified generalized Maxwell model. Prestrain was introduced as a variable of the stiffness of each Maxwell element using simple two-parameter relationships. An algorithm was proposed and numerically implemented to identify the model parameters from the measurements. The performance of the identification method is discussed in terms of accuracy and robustness. The good match between the predictions and the experimental measurements shows that the dependence on the uniaxial prestrain of the complex modulus of the studied composite propellants can be described with few Maxwell elements but with good accuracy.