Optimal Design of Structures with Openings
Date Issued
2015
Date
2015
Author(s)
Tseng, Yen-Ling
Abstract
Prescribed openings are embedded to structures for many reasons like windows, doors, room for pipes, or reducing weight. Stiffness of structures will decrease because of openings. This research is aimed at deciding the positions of openings that will affect the stiffness as little as possible. This research can be divided into two parts. Firstly, the positions of openings are optimized within the design domain. Secondly, topology optimization is considered in conjunction with the first part. The optimization of structures with openings is similar to an embedding problem in topology optimization (Qian and Ananthasuresh 2004), but the stiffness of the embedded objects is zero instead. The steepest descent method is used to determine the positions of openings in such kind of problems. Next, the above problem combining with topology optimization is solved using the multi-level optimization technique, where the element exchange method (EEM; Rouhi et al. 2010) is applied to carry out topology optimization. A restriction of EEM is that the volume at each iteration is same as the objective volume. Because of this, it would be very difficult to design the initial topology with openings. A volume-changeable function (Shih 2013) is employed avoid this situation. Because the steepest descent method is a kind of gradient-based optimization method, the results could be different when different initial position are used. To avoid this situation, different initial arrangements of the openings are adopted. Although the best solution may be not be reached, a better one can always be obtained, where the openings are placed in the inefficient region of the design domain. In the mixed application of topology and the opening optimization, the effect of openings in the process of topology optimization is clearly demonstrated. The multi-level optimization algorithms shown to be very reliable when searching for optimal results.
Subjects
Structural Optimization
Openings
Topology Optimization
Multi-level Optimization
Type
thesis
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