Behaviour of Hybrid Titanium Composite Laminate (HTCL) under In-Plane Loading

Abstract

The Hybrid Titanium Composite Laminate (HTCL) incorporates the mechanical advantages of existing hybrid composite laminates such as ARALL and GLARE while extending their applications to harsh environments. Hybrid composite laminates, consisting of layers of Titanium Grade 2 foils bonded together with fibre-reinforced prepreg plies, have been tested under fatigue loading. HTCL has proven to possess exceptional strength and fatigue resistance. Degraded stiffness and ultimate resistances are provided through experimental stress-strain response of HTCL laminates, which are compared with predicted results by a laminate analysis code. The roles of mechanical degradation, the static and dynamic behaviour and fatigue properties of HTCL are addressed. The development of damage in HTCL specimens during fatigue is shown including titanium ply cracking, interfacial debonding, and layer failure. These tests provided several parameters in order to calibrate a numerical Lamaitre's Continuous Damage Mechanics (CDM) fatigue model, which resulted in good agreement with experimental data. The influence of the fatigue properties of titanium layers on the fatigue of HTCL is discussed. The performance of HTCL laminates in fatigue is shown superior to that of the monolithic titanium alloy for room-temperature conditions.