Damage phenomenon in highly filled elastomers

Abstract

The complete pathway to construct a constitutive model well suited for nite element analysis of highly lled elastomeric materials undergoing large deformation and damage was studied. The e ects of viscoelasticity, temperature, superimposed pressure, cyclic loading and damage in the form of interface debonding were included in the model. Damage initiation and evolution criteria were de ned, and the softening e ect of damage on the stress response was modelled. A robust numerical algorithm was developed and implemented as a user material into a commercial nite element software. The model parameters were determined for a set of solid propellant test data. Using the calibrated constitutive model a systematic veri cation and validation procedure of the implementation was carried out. Homogeneous and inhomogeneous deformation states were considered and various element types were investigated. Model predictions at various loading rates, temperatures and superimposed pressure levels were compared to test data not used in the calibration. Three dimensional stress analysis of a solid rocket motor subjected to cyclic temperature loading was successfully completed. The constitutive model has good predictive capabilities for moderate loading rates, wide range of superimposed pressure levels and cyclic loading. At high loading rates and cold temperatures the model overpredicts the stress response. The implementation is stable and robust in terms of convergence. It is therefore concluded that the constitutive model can be readily used for stress analysis of highly lled elastomeric media with general geometry and loading.