NUMERICAL SIMULATION OF THE STATIC AND DYNAMIC RESPONSE OF CORRUGATED SANDWICH STRUCTURES MADE WITH FRICTION STIR WELDING AND SUPERPLASTIC FORMING

摘要

Corrugated sandwich structures have the potential to find applications in vehicles and vessels subjected to static, dynamic or impulsive loading. A key element of those structures is the geometry of their top and bottom surfaces and the geometry of their core. To justify the use of a corrugated sandwich structure instead of a monolithic plate made of the same material, it is necessary to demonstrate that it will have a superior performance under the expected service conditions while maintaining the same overall ratio of weight per projected flat surface area. Also, an adequate manufacturing process must be established to produce the sandwich structure at a reasonable cost. It has been shown that through the combination of friction stir welding or friction stir spot welding and superplastic forming different types of corrugated sandwich structures can be obtained. In this paper, numerical simulations are used to perform an initial comparison of the static and the basic dynamic characteristics of two of those structures against a monolithic plate of the same material and weight. Rectangular panels simply supported at opposite sides are considered and two different types of analysis are performed: a static analysis in which one of the surfaces of the panels is subjected to a uniform pressure and a normal mode dynamics analysis aimed at obtaining the first natural frequencies and mode shapes. Based on the results of the simulations, preliminary conclusions are drawn regarding the possible use of the sandwich structures under consideration instead of monolithic plates.