Low-energy impact dynamic response prediction of GFRP laminates via analytical methods

Glass fiber-reinforced polymer (GFRP) laminates, extensively applied in automotive lightweight structures, are susceptible to low-energy impacts (LEI) from sources like hailstones or debris, often inducing barely visible impact damage (BVID). During the conceptual design phase, it is necessary to rapidly convert impact energy to dynamic contact forces or deflections. This study presents an analytical solution to overcome the inability of existing methods to solve key dynamic parameters directly due to intricate coupling effects and boundary sensitivity. Three physically meaningful parameters (contact stiffness K _c , boundary coefficient K _b , and membrane coefficient K _m ) are extracted to decouple the anisotropic LEI problem via dynamic response equations. They could be efficiently determined via an inversion technique requiring only single-energy drop-hammer tests within the LEI regime, thus eliminating the need for both anisotropic material constitutive models and multi-energy impact tests. This approach enables rapid obtaining of impact dynamic responses (force/deflection) for composite laminates, which is validated experimentally with prediction errors within 11 %. It provides a rapid tool to optimize layup sequences and material selection, and a practical solution for impact dynamics problem of anisotropic materials.