嵌锁式CFRP方形蜂窝夹芯梁低速冲击响应及失效机理

Composite sandwich beams with a carbon fiber reinforced polymer (CFRP) square honeycomb core were designed and fabricated by using the interlocking method. The dynamic response and failure mechanism of fully-clamped and simply- supported sandwich beams subjected to low-velocity impact were investigated experimentally and the corresponding failure modes of the sandwich beams were obtained. Meanwhile, the damage evolvement process and the failure mechanism were analyzed in detail. Influences of the impact velocity, boundary conditions, the mass distributions of face sheets and the direction of the slots on the failure modes and load-carrying capacity of the sandwich beams were explored. The low-velocity impact experiments of composites specimens with two kinds of boundary conditions were carried out by using the drop-hammer impact test system. Three kinds of initial impact velocity were considered for the simply-supported and the fully- clamped sandwich beams sandwich beams, respectively. In the experiments, the time history curves of the impact load and the midspan deflection of the specimens were recorded by a load cell and a laser displacement sensor. Meanwhile, the deformation processes of the sandwich beams were captured by a high-speed camera. The experimental results show that the directions for the slots of the long ribs have significant influence on the failure modes of the sandwich beams. The sandwich core with the upward slots at the midspan has compression deformation whilst the cracking failure along the direction of the downward slots at the midspan is observed due to the tension, which results in the face-sheet debonding and rib fracture successively. It is found that for the same mass, the design of the thicker upper face sheet can enhance the impact resistance of the sandwich beams. The peak load and load-carrying capacity of the sandwich beams increase with increasing the impact velocity. The fully-clamped boundary conditions make the sandwich beams exhibit hardening post-failure behaviors obviously. After the initial failure at the midspan, the fully-clamped ends of the cores and the face-sheets of the sandwich beams experience the fracture failure.