Impact characteristics of S2-glass fibre/FM94-epoxy composites under high and cryogenic temperatures: Experimental and numerical investigation

The aerospace industry uses glass fibre reinforced polymer (GFRP) composites to manufacture structural and non-structural parts of an aircraft as they possess superior strength to weight ratio and exceptional corrosion resistance. Commercial aircraft operate in a very wide temperature ranges from -54 to 55 degrees C. Potential GFRP laminates are susceptible to impact during aircraft operation, and the temperature at impact governs the nature of damage and failure mechanisms. As a result, the current study focuses on examining how aeronautical GFRP composites behave in various temperature environments that are encountered during high- and low-altitude operations. Using S2-glass fibre/FM94-epoxy unidirectional prepreg, GFRP plates were created. Drop weight impact tests were conducted at ambient (25 degrees C), high (50, 75, 100 degrees C), and low (-25, -55 degrees C) temperatures, as well as at various impact energies (75, 150, 225 J). The damages were assessed visually, along with their sizes. Each testing scenario's impact parameters, including the impact load, deflection, and energy absorption, were also examined. In Abaqus/Explicit, a coupled temperature-displacement numerical model was created to predict the onset of stress and damage. According to experimental findings, GFRP plates are stiffer and show less apparent damage at cryogenic temperatures (similar to 15-34 % lower displacement) than they do at other temperatures. Furthermore, it was observed that the matrix softens at high temperatures, showing larger damaged area at entry but with less obvious damage and increasing energy absorption, while semi-perforation occurred under cryogenic temperatures at entry with smaller damaged area. A strong correlation is shown between the experimental and FE data, confirming the capability of FE models to predict impact damage and deflections at different temperatures in the future.