The influence of asymmetric faces on low-velocity impact failure of CFRP/aluminum foam composite sandwich beams

The influence of asymmetric faces on dynamic failure of fully clamped CFRP/aluminum foam composite sandwich beams subjected to low-velocity impact was studied. Three kinds of geometrically asymmetric sandwich cross-sections with an equal area density were designed. The low-velocity impact experiments of the composite sandwich beams were carried out to explore the dynamic response and the failure modes. Initial failure modes of top face fracture, indentation and core shear were found. The final failure modes, including top face fracture, core shear, bottom face fracture at one end and debonding between core and bottom face, were observed. It is shown that the composite sandwich beams experience the elastic bending to large deflection. The impact load is strengthened and increases rapidly at the large deflection stage due to effect of the fully clamped boundary. Furthermore, the quasi-static theoretical models were employed to predict the dynamic response of the composite sandwich beams. the theoretical models can capture the elastic bending of the composite sandwich beams reasonably, while the initial failure loads are slightly underestimated. The comparisons of peak load and midspan deflection suggest that the asymmetric composite sandwich beams with a thinner top face have better impact resistance than other designs of the faces.