Dynamic mechanical properties and constitutive model of photosensitive resin specimens at different temperatures

In order to reveal the dynamic mechanical properties of resin-molded parts prepared from photosensitive resin composition at different temperatures, four typical service temperatures (26 °C, 50 °C, 70 °C and 90 °C) were selected, and the mechanical properties of photosensitive resin specimens under quasi-static and high strain rate (1200 s −1 , 1500 s −1 and 1800 s −1 ) loading were tested by universal material testing machine and split Hopkinson pressure bar (SHPB) experimental device. The stress–strain data of the material were obtained. Results show that the stress of photosensitive resin specimens decreases with the increase of temperature under quasi-static and high strain rate loading conditions, reflecting a certain temperature softening effect. Two typical stages of strain softening and strain hardening exist in the quasi-static compression process of the specimens at room temperature, while the specimens only exhibit strain hardening at 50 °C, 70 °C and 90 °C. Under dynamic loading, the elastic modulus, peak stress and peak strain of the photosensitive resin increase with the increase of the strain rate, reflecting an obvious effect of strain rate strengthening. The nonlinear thermo-viscoelastic constitutive model can better describe the mechanical behavior of the material under high strain rates and service temperatures, and the experimental values are in good agreement with the fitted values of the model. The results can provide theoretical model and method support for the design and development of resin-based materials and the optimization of their mechanical properties.