Influence of Preloading on Damage in CFRP Composite Material Subjected to Low-Energy Impact Loads

A major challenge in the operation of aerostructures made of carbon fiber-reinforced polymer (CFRP) composites is their vulnerability to impact-induced damage, particularly when access is limited to only one side of the affected structure. This issue becomes even more complex considering that damage typically occurs in components subjected to initial static preloading. The objective of this study was to investigate the influence of static preload on the extent of damage in CFRP composites subjected to impact energy and to evaluate the effectiveness of selected non-destructive testing (NDT) methods in damage detection. Experimental investigations were conducted on a series of CFRP specimens impacted using a drop-weight tower. Each impact event was recorded with a high-speed camera operating at ultra-high frame rates. It was demonstrated that both the contact time between the impactor and the specimen, as well as the extent of internal damage assessed using ultrasonic testing (UT) and computed tomography (CT), were significantly affected by the level of applied static preload.