Design and Optimization of Hybrid Interface Joint in a Composite Fan Blade of Aircraft Engine

Abstract

Fan blades are one of the most important components of an aircraft engine. Bird strikes on fan blades have always been a cause of worry and it can cause slices of birds hitting other parts of the engine which may lead to greater damages. Bird strikes cannot be completely avoided. However, reduction of the impact of a bird on jet engines can be achieved by suitable design and manufacturing, through the simulation analysis. Although current composite blades can withstand the bird strike impact, some delamination failures are still observed on the trailing edge side of the blade, possibly due to vibration bending modes This paper talks about using two fibers in composite blade instead of the current single fiber one. For this to be feasible, two fiber joints at various locations on the blade have to be properly designed. The design criteria used here is the lowest inter-laminar shear strain level at critical joint locations. Suitable size coupon models in FEA with hybrid joints inside are used to simulate the blade bending with appropriate boundary conditions. The coupon models were developed by using the ANSYS APDL and linear static analysis was performed for different repetitive layups and varying layer by layer joint locations. The coupon joint designs with minimum inter-laminar shear strains are shortlisted to be recommended for use in sub-element and blade models.