Study on Mechanical Properties and Constitutive Models of Epoxy Resin under Low Strain Rate Tension and Compression

Epoxy resin (EP) can be flexibly bonded to various materials and has a wide range of applications in aerospace manufacturing.One of the most common applications is as a matrix phase in the preparation of advanced fiber composites.Therefore, it determines the mechanical properties of composites, particularly in view of the effect of differences in strength.To this end, we prepared tensile and compressive specimens of EP according to the ASTM standard and carried out quasi-static loading tests at different strain rates (0.001 to 0.1 s -1 ).The results show that EP has an obvious strain rate dependence, and the elastic modulus, yield strength, and plastic flow platform in tension and compression have obvious differences.Furthermore, by fitting the experimental stress-strain curves in tension, we used the power function to establish a theoretical model in terms of yield stress and elastic modulus.Subsequently, the nonlinear constitutive models in the compressive state were established based on the Sherwood-Frost model.Thus, a complete constitutive model was obtained which takes into account both tensile and compressive differences.Based on these constitutive models, the tensile and compressive mechanical behaviors obtained by parameter inversion are in good agreement with their experimental results, proving that the developed constitutive models have good theoretical prediction capability.These research results provide a reference for the practical engineering application of EP, especially for the fiber-reinforced EP composites.