A comprehensive study of low-velocity impact behavior and damage evaluation of angle-ply thin woven GFRP composites under elevated temperatures

Abstract

The recent climatic changes have resulted in a significant increase in temperatures over 50 °C during summer midday in certain countries. This has motivated the study of the low-velocity impact (LVI) response of angle-ply thin woven glass fiber-reinforced polymer composites under temperatures of 25 °C, 50 °C and 75 °C. The LVI performance of the laminates was assessed by eighteen parameters. A new inexpensive image processing method is developed to accurately measure the damage diameter, area, and perimeter length, which significantly aids in analyzing the damage mechanisms under various test conditions. The damage perimeter length is a new parameter that is used to interprets the change of material behaviors with temperature. The LVI results showed that the impact bending stiffness is increased with impact energy (Ei) due to increasing strain rates, which leads to decreasing the molecular mobility of polymer chains and hence, the materials tend to behave more brittle. Delamination threshold force increased with impact energy and vice versa with temperature. Soaking the specimens for 1 h at 50°C improved post curing and thus, enhanced the cross linking density, which significantly improved most of the impact properties. The penetration energy threshold of 25.5J (85 % of Ei) is observed at 30J-50 °C. Relaxation of the polymer chain within the glass transition region at 75°C leads to full fracture energy threshold at 30J, which correlated with open force-deformation curve, absorbed energy of 100 %, zero elastic energy, zero rebound energy, zero rebound velocity, and increase contact duration. The proposed multivariate regression models accurately predict the impact properties.