High-velocity impact and post-impact fatigue response of Bismaleimide resin composite laminates

Abstract

Bismaleimide (BMI) resin composite is a kind of thermoplastic composite that has attracted a lot of attention for its advantages in fracture toughness and damage tolerance. The composite structures are usually exposed to the threat of foreign object impact during service; static strength and fatigue resistance of composite structures with impact damage will dramatically degrade, which can lead to catastrophic damage of composite structures. In this paper, the hard foreign objects and air cannon were used to conduct a high-speed impact test on the BMI composite laminate. The effect of impactor diameter, impact velocity, and impact angle on impact damage size and microscopic damage mechanism was investigated; respectively, the results show that damage width and length increase with the growth of impact velocity and impactor size, the impact velocity has a greater impact on damage depth, and various impact angles will significantly change the damage morphology. After impact, the step-by-step method was used to analyze the fatigue strength of composite laminates with impact damage; it was found the depth of impact damage has the biggest impact on the fatigue strength. Based on conclusions of the fatigue test, a prediction model was proposed to predict the fatigue strength of composite laminate with the impact damages; the results show that prediction results are within 1.5 times of the error band. This paper reveals the damage behavior of composite laminate under high-speed impact; the proposed fatigue strength prediction method can provide a reference for the safety evaluation of composite structures.