Wright State University School of Graduate Studies

Alyanak, Edward J. Ph.D., Department of Mechanical and Materials Engineering, Wright State University, 2006. Efficient Reliability Based Design and Optimization of Structural Systems Using Evidence Theory. A computationally efficient methodology was developed to make utilizing evidence theory in reliable optimization feasible. Evidence theory was adopted because of its ability to handle both epistemic and aleatory uncertainty sources. The methodology allows the projection of the reliability gradient without introducing more computational cost than is necessary to find the evidence theory values of belief and plausibility. The method can also project a gradient for cases when a system is completely safe or completely failed. This represents an advancement over other techniques that return a zero gradient in these cases. Further advancement in the calculations of plausibility decision was made. Compared to previous methods, these advancements significantly reduce computational cost of the calculations involved in determining plausibility decision. Example problems are provided in the areas of mechanical, space, naval, and aeronautical engineering. In addition to the work with evidence theory, a methodology was developed to consider the overall size, shape, and structural arrangement of a supercavitating torpedo structure. The presented supercavitating torpedo design is optimized for these variables. The results of this research are contained within the following dissertation.