Macro-mechanical Modeling Approach for Simulating Ballistic Damage to Composite Rotor Blades

A modeling approach was developed for simulating non-explosive, ballistic damage to composite structures using finite element analysis. The research focused on a macro-mechanical representation of the composite laminate, that is, the laminate was modeled with a single shell element through the thickness. This approach was investigated due to its advantages over a micro-mechanical approach where multiple finite elements though the composite thickness are used to represent the laminate. The advantages include low computational cost and lower resources required to generate material properties however, out-ofplane damage modes (delamination) cannot be physically modeled. Simulation of a composite rotor blade structure subjected to impact and perforation of a ballistic projectile was used to demonstrate the capability of this approach. A step-by-step modeling procedure from coupon level to full scale level was developed to establish confidence in the simulation results prior to obtaining full scale ballistic test results. Damage from full scale ballistic tests was compared to the simulation results. Reasonable correlation was found for the composite material loss between the test and the simulation. Although delamination was not physically modeled in the simulation, the extent of matrix damage predicted had reasonable agreement with the extent of delamination found in the tests.