A Study of the Dynamic Behavior for Low Velocity Impact on Thin Composite Laminates

During the last two decades, research on the development of structural components with high crashworthiness has been carried out by the automobile, aeronautics, naval, trains and elevators industries. Many kinds of components have been made using composite materials, because these materials can absorb high amount impact energy and can guarantee the survival of the passengers. However, the dynamic behavior of composite laminates is very complex because there are many concurrently phenomena during composite laminate failure under impact load. Fiber breakage, delaminations, matrix cracking, plastic deformations due contact and large displacements are some effects which should be considered when a structure made from composite material is impacted by a foreign object. Thus, an investigation of the low velocity impact on thin composite laminates of epoxy resin reinforced by carbon fiber is presented. The study shows the technology to manufacture the specimens and the set-ups of equipments to make dynamic experimental tests using a drop-tower instrumented. Afterwards, non- destructive evaluation (NDE) using ultrasonic C-Scan was carried out in order to determine the main kind of failure. The influence of stacking sequence and energy impact were investigated using load-time histories, displacement-time histories and energy-time histories as well as images from NDE. Finally, indentation tests were developed and the quasi-static results were compared to dynamic results, verifying the inertia effects when thin composite laminate were impacted by foreign object with low velocity.