Structures often consist of composite members containing holes or notches. Since stress concentrations associated with such geometric discontinuities can decrease strength, there is desire to minimize stress concentrations. This article demonstrates ability to reduce tensile stress concentrations in perforated composites by synergizing a finite-element program with a feasible-direction method to optimize fiber directions locally, i.e., form a functionally graded material. Optimization is conducted under constraints on the maximum stress in the structure. In addition to reducing the tensile stress concentration beyond that achieved by previous methods, the current approach is compatible with contemporary processing techniques.

No abstract

A sandwich panel, composed of hybrid laminate skins of AL (aluminum)-CFRP-GFRP and aluminum honeycomb core, was optimized for maximizing the structural performance. Stacking sequence of the three different materials comprising the hybrid laminate skins and individual ply angles are taken as design variables in the present optimization problem. Synergizing a particle swarm optimization (PSO) algorithm method with a specially developed FEM program enables one to optimally decide the design variables and thereby significantly improve the sandwich performance. The present technique applying PSO to a hybrid sandwich in conjunction with FEA has extended the application area of optimization with a complex honeycomb sandwich that is not possible by the conventional method.

No abstract

Article history:The dynamic responses of a telescope loaded on an STSAT-3 satellite were analyzed, and environmental tests were conducted to verify the reliability of the design. The space use telescope COMIS (compact imaging spectrometer) is a major payload of the STSAT-3 launched on November 21, 2013. Vibration responses such as the acceleration, displacement, and velocity with respect to random vibration and shock impulse inputs were obtained based on theoretical fundamentals in conjunction with finite element analysis. The main focus of this study was on developing technology for accurate and/or favorable modeling and analysis of the structure and fitting the results to that of experiments. Cutting-edge technology for manipulating the vibrations of a space use telescope is suggested.