Effect of strain rate on the compression behavior of vinyl ester resin casting

Quasi-static and high st rain rate compressive experiment s on the vinyl ester resin casting were carriedout by using a material universal testing machine and Hopkinson bar , and the behaviors of compressive instabilityand f racture of the resin casting at different st rain rates were investigated. The result s indicate that the response behavior of the resin casting is cont rolled by different mechanisms at different st rain rates and some mechanical properties of vinyl ester casting are rate-dependent : the castings are dest royed in a toughness mode at st rain rate 3. 3 ×10^-4 / s～6. 6 ×10 ^-3 / s , while the castings are dest royed in a brittleness mode at st rain rate 950/ s～5800/ s. Theyield st ress , yield st rain energy density are all increased with the increasing of st rain rates under quasi-static loadingas well as under high st rain rates loading. What is interesting is that the yield st rain is decreased with the st rain rateincreasing under quasi-static loadings while it is increased under high st rain rate loadings. It is considered that in thecasting there occurred forced high elastic deformation at high st rain rates. The damage of the specimens is mainlycont rolled by axial st ress before unstable deformation , while mainly cont rolled by shear stress after unstable deformation , and then all f racture finally. The development of the cracks inside the castings is also rate-dependent .