Impact of temperature on LVI-damage and tensile and compressive residual strength of CFRP

Abstract

This study investigates the influence of temperature and impact-energy on low-velocity impact damage in CFRP and the resulting residual tensile and compressive strength. Impacts were introduced at −20∘C,20∘C and 80∘C, which are moderate temperature compared to the glass transition temperature of 203∘C of the used CFRP. A change in temperature leads to a substantial change in damage behaviour. With increasing temperature, the delamination area is reduced, and at 80∘C fibre-failure occurs on the impacted side. The residual tensile strength was tested at 20∘C utilising a new jig, which counteracts the stresses resulting from free-edge effects and thus prevents that edge delaminations are overshadowing the effect of the impact damage due to the specimen size. The fibre failure reduces the residual tensile strength significantly compared to the damage resulting from impaction at 20∘C. The compressive residual strength was determined at 20∘C and 80∘C. The results point out that the temperature mainly determines the residual compressive strength. Consequently, it is essential to identify the material’s behaviour in the range of the in-service temperatures, even if they are far away from the glass transition temperature, to evaluate the damage tolerance and performance.