Damage mechanics applied to elastic properties of polymers

The elastic properties of Polystyrene (PS) and High Impact Polystyrene (HIPS) have been investigated using one-dimensional and two-dimensional damage mechanics models. The damage mechanism of these polymers is crazing. However, their mechanical properties are different. The PS specimens behave in a predominantly elastic manner, whereas HIPS displays a large amount of plasticity. A series of uniaxial tensile tests has been carried out to determine the respective damage parameters and damage strain energy release rates. The results of the experiments illustrate that anisotropic damage occurs in PS and HIPS, even under uniaxial loading. The damage strain energy release rate of HIPS is very much higher than that of PS. These results are then used to examine the applicability of the damage model to express the damage. The principal directions of the damage of PS and HIPS are also discussed.