Structural topology optimization with implicit design variable-optimality and algorithm

Haney, Mark, Ph.D., Department of Mechanical and Materials Engineering, College of Engineering and Computer Science, 2006. Topology Optimization of Engine ExhaustWashed Structures. Aircraft structure subjected to elevated temperature and acoustic loading present a challenging design environment. Thermal stress in a structural component has typically been alleviated by allowing thermal expansion. However, very little work has been done which directly addresses the situation where such a prescription is not possible. When a structural component has failed due to thermally-induced tensile stresses, the answer to the question of how best to stiffen the structure is far from trivial. In this work, we demonstrate that conventional stiffening techniques, for example, those which add material to the thickness of a failing panel, may actually increase the rate of damage as well as increasing load into suband surrounding structure. The typical compliance minimization topology optimization formulation is applied to a thermally-loaded panel resulting in extremely nonoptimal configurations. To generate successful thermal stress designs where the objectives are to lower the tensile stresses while simultaneously limiting the amount of additional load into suband surrounding structures, a well-known characteristic of topology optimization for a single-load case mechanical loading is exploited which by construction limits additional load into surrounding structure. Acoustic loading is also a major concern as exhaust gases with random frequency content impinge on aircraft structure in the vicinity of

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Topology Optimization of Engine Exhaust-Washed Structures

A new approach to optimal design of elastic structures

In this paper, methods of local and global searches of approximate optimal designs are presented for regular frames subjected to static loads. Constraints are given for stresses and displacements.

Local and global searches of approximate optimal designs of regular frames

One of many optimization techniques is the evolutionary structural optimization (ESO), based on the idea that an optimal structure can be achieved by gradually removing ineffectively used materials from the design domain. Production of a multistage optimization is often proposed to reach the best overall solution. In the first stage, the structure is optimized according to a topology criterion, and, in the second stage, sizing optimization is carried out. The efficiency of such an approach is questionable as a fixed topology, for the second stage optimization may not be the most favorable before sizing optimization is carried out. In this paper, the simultaneous topology and size optimization of trusses using the ESO algorithm are discussed. A number of numerical examples are presented to research capacity to achieve optimal solutions for a structural problem. The topology design of the initial design domain is based on commonly used designs for multistorey trusses constructed from straight members. There...

https://journals.sagepub.com/doi/pdf/10.1155/2014/864807

Simultaneous Topology and Size Optimization of 2D and 3D Trusses Using Evolutionary Structural Optimization with regard to Commonly Used Topologies

This paper treats optimal design of an elastic truss subject to alternative loads and stress constraints. Necessary and sufficient conditions for local optimality of a fully stressed design are derived by the method of Lagrange multipliers. These criteria provide practical means of determining whether a given fully stressed design is or is not optimal.

Geir A. Gunnlaugsson

Papers

Optimality Conditions for Fully Stressed Designs