Modeling low velocity impact phenomena on composite structures

The investigation of the mechanical response of fiber-reinforced composite laminates under impact loads can be very challenging due to the occurring simultaneous failure phenomena. Indeed, as a consequence of low velocity impacts (LVIs), intralaminar damage like fiber and matrix cracking and interlaminar damage such as delamination often take place concurrently, leading to significant reductions in strength and stability of the composite structure. In this paper a numerical study is presented which, by means of nonlinear explicit FEM analyses, aims to characterize the impact-induced damage in composite laminates under a LVI, emphasizing the relevance of the numerical model complexity on the correct simulation of the impact phenomena. The numerical results, obtained from the proposed numerical model implemented in the FEM code ABAQUS by means of a user subroutine, have been compared with results obtained by adopting the standard ABAQUS formulation and with experimental data (experimental force vs time, force vs displacement, energy vs time curves). Hence, a first validation of the proposed numerical approach has been attempted and its effectiveness with respect to standard approaches has been preliminarily assessed.