Abstract
There are attempts to develop a hybrid (S-glass–carbon) composite fan blade which can show excellent damage resistance under bird strike kind of loading. Some part of the carbon fiber composite blade is to be replaced with S-glass and to achieve this, carbon–glass joints need to be optimized. The main technical challenge in this, is the robustness of the interface region between S-glass and carbon plies. The interface region optimization in terms of ply layups and overlaps has been performed and a few promising cases of interlock configurations have been proposed in this context. As part of this interlock region structural evaluation task, representative composite coupons were made, and bird strike impact tests were performed. This article presents the bird strike analysis results of these interlock ply-by-ply coupons and the correlations of these analysis results with the actual bird strike test results performed on these coupons. Overall analysis to test results correlation has been satisfactory and detailed comparisons are shown in this article. The coupon-level bird strike analysis methodology was enhanced by including the resin pockets that results in the interlocking regions. The understanding obtained from this work will be used as guideline for designing and validating the hybrid composite blade for aircraft engines.