Nonlinear shear behavior of composite laminates at various temperatures and loading rates

In this study, the nonlinear shear behavior of composite laminates at various temperatures and loading rates is experimentally investigated. A total of five temperatures (25 °C to 120 °C) and four loading rates (0.1 mm/min to 200 mm/min) are set to examine their effects on the material's mechanical response. The results showed that the shear strength decreased by 54.4 %, 49.1 %, 45.7 % and 44.3 % at the four different loading rates as the temperature increased from 25 °C to 120 °C, suggesting thermal softening of the material and a corresponding reduction in shear modulus. The shear modulus and strength increase with loading rate, with the shear strength at 25 °C rising from 53.84 MPa at 0.1 mm/min to 68.67 MPa at 200 mm/min, reflecting the material's enhanced resistance to shear deformation at higher strain rates. A significant interaction between temperature and loading rate is observed, particularly at elevated temperatures ( T>T_g), where the shear modulus exhibits a pronounced sensitivity to the loading rate. Particularly, a novel nonlinear shear model based on viscoelastic theory is proposed accounting for the interactive effects of loading rate and temperature. The minor deviation between the predicted and experimental results (R² > 0.99) indicates that the model can demonstrates that the model can accurately capture the nonlinear shear behavior of composite laminates.