A REFINED NONLINEAR-ANALYSIS OF PRETWISTED COMPOSITE BLADES

A nonlinear formulation for the structural behavior of initially twist ed solid and thin walled composite blades is presented. The model is d esigned to handle arbitrary thick solid cross-sections or general thin -walled geometries, and includes three-dimensional out-of-plane warpin g. The nonlinear scheme enables the inclusion of geometrical nonlinear ities in the presence of large initial twist, and is based on a formul ation that preserves three-dimensional effects and continuity of displ acements, rotations and detailed warping distributions. A basic and im portant feature of the present analysis is the fact that the quasi-lin ear solutions that are employed throughout the iterative process are e xecuted for the blade as a whole. This allows one to determine and pre serve complex three-dimensional effects including warping continuity w hich are usually lost by standard segment discretization schemes. A st udy of the combined effect of initial twist and composite induced elas tic couplings is presented in addition to a correlation with nonlinear experimental data. (C) 1997 Elsevier Science Ltd. All rights reserved .