Failure analysis of tapered composite propeller blade

Abstract

This research provides a thorough investigation on aspects of the structural integrity of composite blades for a range of operating conditions using fluid-structure interaction analysis based on Computational Fluid dynamics (CFD) and Finite Element Method (FEM). Both shell elements and layered solid elements were used in the finite element model. The strength was assessed against Tsai-Wu, Hashin, and Hoffman criteria. The blade is subjected to combined loads of bend and twist that varying in magnitude, direction, and acting point therefore, the critical failure mode is shown to be highly affected by operating conditions which necessitates evaluating the strength for the whole operating range. The safe operating range was analyzed according to a guidance note recently released by Bureau Veritas (BV) which defines safety limits for individual and combined stresses across each ply. Interlaminar normal stress failure is shown to be the most critical mode of failure, hence a solid model is recommended over the shell model. The blade strength meets the requirement of BV rules when assessed by Hoffman criteria however, other failure criteria show insufficient strength at the design condition.