A simple method is presented to characterize the nonlinear unloading and residual deformation behavior of foams. Combined with hyperelastic constitutive model and elastoplastic constitutive model, plastic foam is considered to be composed of two layers of hyperlastic layer and elastic plastic layer from the same cross-sectional area but different thickness. The two layers have the same loading behavior, which are linear elasticity, yield platform and compaction. However, the unloading performances of the two layers are different, while hyperelastic layer is unloaded according to the Mullins effect law, and the elastic-plastic layer is unloaded according to the linear elastic mechanical behavior, respectively. Then, based on the results of EPS uniaxial compression test, the results of 9 parameters in the constitutive model of hyperelastic layer and elastic-plastic layer are obtained. These parameters can simultaneously characterize the mechanical behavior of nonlinear unloading and residual deformation. Finally, the dynamic response of EPS is predicted by using two-layer constitutive model. The experimental results are consistent with the theoretical results to confirm the effectiveness of the proposed method.
Key words: nonlinear unloading; residual deformation; hyperelastic constitutive; elastoplastic constitutive; consecutive multiple impacts
Key words
nonlinear unloading /
residual deformation /
hyperelastic constitutive /
elastoplastic constitutive /
consecutive multiple impacts
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