Grid-Characteristic Numerical Method for Low-Velocity Impact Testing of Fiber-Metal Laminates

Abstract

The grid-characteristic numerical method (GCM) for hyperbolic equations systems is applied in many science fields—gas dynamics, hydrodynamics, plasma dynamics, etc. Its application for problems of dynamics of deformable solids is less popular, especially in comparison with finite elements methods. GCM shows good results and high performance for elastic wave problems in the approximation of small deformations—seismic survey and ultrasound non-destructive testing in medicine, aviation and railway industry. Low-velocity impacts (hail, dropped tool, bird strike, etc.) are one of the most dangerous load types for polymer composites. They cause barely visible impact damage (BVID) that can only be detected by a thorough ultrasound testing, but severely reduces the residual strength of the material, especially for a compression load along the surface. This testing increases the operating cost, and its necessity can be easily missed, which greatly reduces the reliability of polymer composites. Hybrid fiber-metal composites (GLARE, ARALL, titanium composite laminates) were developed to unify the advantageous properties of polymer composites and metal. The addition of a thin metal layer (1–2 mm) helps to reduce the impact vulnerability of polymer composites in case of a penetration or significant deformations of the material. The application of GCM for low-velocity impact problems can help to explain the damage pattern in fiber-metal composites in case of low-velocity strike, including delamination effects, by modelling elastic wave processes in the complex anisotropicmedium. This article contains the brief description of the GCM and numerical results that were obtained for model problems of a low-velocity impact on titanium composite laminates.