الفهرس 
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Abstract
The capability of enhancing the efficiency by exploiting the elastic response of composite propeller has been a controversial research point. Contradictory findings are noticed as some studies concluded that composite propeller does not outperform metallic propeller while other succeeded to obtain efficiency improvement at certain operating conditions. This research investigates geometric aspects of flexible composite propeller insisting in factors important for selecting appropriate initial model in terms of hydrodynamic forces and moments governing hydro-elastic response of the blade. Criteria for assessment of the model were introduced and have been applied on a case of propeller VP1304. Parametric study was performed varying two geometric design variables of propeller, namely, pitch and skew distribution. Hydrodynamic twisting moment resultant from pressure load was defined as the effective hydrodynamic output parameter suitable for preliminarily predicting blade structural behaviour. Comparison of moderate and high skew models in term of nondimensional twisting moment showed that increasing blade skew reduced pitching moment at low advance coefficients which is advantageous while at high advance coefficients, skew resulted in unfavorable increase of de-pitching moment. Accordingly, recommendations for optimization process at both design and off-design conditions was presented. Besides hydrodynamic performance, another challenging issue in composite propellers is the lamination of thin bladed composite marine propellers, which necessitates dropping layers following thickness variation to produce lighter propeller with good elastic damping. Strength evaluation of such tapered laminate is a highly nontrivial process that include significant interaction between fluid and structure, as composite blades are subjected to multiaxial loads resulting from nonuniformly distributed hydrodynamic that cause the blade to undergo combined structural response of bent and twist. This research work includes optimizing composite propeller strength using unconstrained stacking-sequence and fully coupled CFD-FEA analysis. Composite model is configured for propeller VP1304 after modification on blade thickness and, initial analysis on balanced-stacking of [0,90,45,-45] were set as a benchmark for optimization process targeting to minimize failure index. This is calculated according to Puck failure theory considering fiber and matrix failure as well as delamination. Delamination is evidenced to be the utmost critical mode of failure whereas, the optimization resulted in an optimum laminate with unbalanced nonsystematic stacking that succeeded to reduce interlaminar stresses, avoid failure and, reduce maximum value of IRF (Inverse Reserve Factor) by 50% compared to the predefined balanced-stacking benchmark. Furtherly, the weight of the blade is reduced by 85% compared to metallic blade.