Experimental Verification of Finite Element Analyses of Propeller Strength

Abstract

Propeller strength analysis and prediction methods were investigated. The primary tool was the finite element technique. More specifically, the thins hell approximation was adopted and modeled by a commercially available (MARCCDC) program. To verify that the program was performing correctly, holographic, strain gage, and stress coat experiments were performed on model and full-size propellers. Static loads were applied and measured together with displacements, strains and stresses. Comparison of the results of the numerical (FEM) solutions to the experimental results shows that this method is highly reliable. The experimental results also show patterns in the behavior of the blade which can guide the formulation of a design tool for the strength analysis of a propeller without r e course to the finite element analysis (except at the end of the design, as a final check ). Instead, a modified beam theory, based on observed patterns, can guide the designer to optimum design shape for hydrodynamics and strength.