NONLINEAR PERFORMANCE OF A POLYURETHANE ISOLATOR WITH LARGE IMPACT

Shock isolator is widely used in mechanical areas for its performance in vibration damping noise elimination and so on. We studied a kind of polyurethane isolator, by considering its large deformation under strong mechanical impact. Nonlinear behavior became a key characteristic as the load-displacement curve presented a steep slope when the compression strain reached more than 20%. In order to predict its dynamical behavior which could take into account nonlinear performance, two models were used, which were respectively Maxwell model and Frictional solid model. PSO (Particle swarm optimization) algorithm was used to identify parameters of the models based on the result of drop weight test. It showed that the first model had advantage in characterizing the damping property of the isolator, while the second was better in considering internal friction property. Therefore, these two models were combined with each other so as to develop a viscoelastic-elasticplastic model with nonlinear coefficients. The model had a better accuracy in characterizing the nonlinear performance. Theoretical predictions based on the combined model agreed well with results of drop weight test.