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Traditional propellers are made of high-stiffness metal material. They deform only slightly and are usually designed to work at a constant speed, operating at reduced efficiency at other speeds. This research designs a composite propeller that operates over a wider range of speeds. The deformation of propeller is determined by orientating fibers to produce propellers that are more efficient than those made of metal. First, structural and fluid dynamic calculations are performed to determine the deformation, the fluid pressure, and the performance of the propeller. An optimizing genetic algorithm is then used to determine the best stacking sequence of the propeller; however, if the optimal stacking sequence does not outperform a metal propeller, a predeformed design is then used to solve this problem. A smallest pitch stacking sequence is obtained using a genetic algorithm first, and then the propeller is displaced in the opposite direction to form a predeformed propeller. The predeformed propelle...

Contact stresses and residual bearing strength of pin-loaded composite laminates at different temperatures are investigated. An incremental finite element code, based on the updated Lagrangian approach, was developed for determining the contact stresses near a pin-loaded hole in composite laminates under combined thermal and mechanical loadings. Based on the progressive damage model, the quadratic strength theory combined with a proposed failure simulation are adopted for failure predictions. In the stress and strength analyses, mechanical properties of the laminates are assumed to be temperature dependent. Numerical results include the distributions of initial (thermal) as well as total contact stress around the pin-loaded hole, residual bearing strength, and failure mode for a single-fastener clearance-fit joint with an elastic pin. The bearing strain model test has been performed at elevated temperature for the verification of present calculations.

This paper is to analyze the instability of plate structure subjected to in‐plane periodic forces. By using the finite element method, the regions of dynamic instability of beam, plate, plate with a hole, and stiffened plate are analyzed. These analyses can be used as a reference in the design of plate structure under dynamic forces. The isoparameter element used in this paper takes account of transverse shear deformation. It has the advantage of being quite versatile. The results are in good agreement with those in other literature.

This paper presents a computer program based on finite element method for elastoplastic buckling strength analysis of plate structures. To deal with the material nonlinearity problem, this program applies linearization technique at each loading increment. And the amount of loading increment at each stage is to make one element yield at a time. So by this process we can trace the plastic zone developed during elastoplastic buckling. One outstanding characteristics of this program is that by employing a variant gaussian elimination associated with Sturm sequences property, it eliminates the need of solving the buckling eigenvalue problem at each increment loading stage that is associated with the usual solution techniques. The validity of this program is varified by comparing its numerical results with theoretical and experimental ones.