نوع مقاله : مقاله پژوهشی
موضوعات
عنوان مقاله English
نویسندگان English
In this study two viscoelastic analytical models -the four-parameter Burgers model and the single-integral Schapery model- were compared, analyzed, and evaluated for predicting the long-term creep behavior of glass/vinylester composite laminates. The parameters of the Burgers viscoelastic model were characterized using available experimental data. Since using the same set of characterized parameters from the creep stage in the recovery stage resulted in significant discrepancies between experimental results and the Burgers analytical model, the model parameters for the creep and recovery stages were characterized separately. The results obtained from the Burgers model showed significantly better agreement with experimental data for glass/ vinylester composite laminates, especially at high temperature and stress levels, compared to the Schapery model. This agreement was observed clearly in both the creep and recovery stages. Furthermore, the effects of temperature and stress on the variations of the Burgers model parameters were investigated, revealing that these parameters change with varying temperature and stress levels. Subsequently, the governing equations describing the variation of these parameters with respect to temperature and stress were derived. Finally, the creep compliance, creep modulus, damage factor, and creep strain rate were calculated at each stage. The results for glass/ vinylester composite laminates indicate that with increasing temperature and stress levels, the creep compliance, damage factor, and creep strain rate increase, while the creep modulus decreases.
کلیدواژهها English