Repeated Low-Velocity Impacts on Dynamic Failure Mechanisms of Composite Sandwich Panels With PVC Foam Cores

Composite sandwich structures have been widely used in naval architecture and ocean engineering field, thanks to their excellent properties like high strength to weight and stiffness to weight ratios, favourable energy-absorbing capacity, reduced corrosion tendency and design flexibility. Due to complex service conditions such as collisions, ice impacts, aircraft landing impacts and falling object impacts, composite sandwich structures in marine engineering field are commonly subjected to repeated low-energy impacts at localized sites during complex service conditions, and its resultant damage may seriously affect their mechanical performance and structural safety. Therefore, to provide insight into dynamic failure behaviours, this paper performed a series of repeated low-velocity impact tests on the orthogonal woven glass fibre laminated sandwich panels with a PVC foam core layer. The variations of the mechanical characteristics and failure behaviours of composite sandwich panels against impact numbers are explored, such as peak force, dent depth, structural stiffness, failure modes and energy absorption. It is found that the accumulated impact-induced damage has a significant negative effect on the structural stiffness, failure mode, and energy absorption characteristics of composite sandwich panels. The PVC foam cores show a good energy absorption ability to protect the integrity of the bottom face sheet from repeated impacts. This research provides a detailed understanding of the damage mechanisms of composite sandwich panels under repeated impacts.