doi:10.1016/j.cad.2008.07.004
Copyright © 2008 Elsevier Ltd All rights reserved.
Shape feature control in structural topology optimization
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Shikui Chena, Michael Yu Wanga,
,
,
and Ai Qun Liub
aDepartment of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin, NT, Hong Kong
bSchool of Electrical & Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore
Received 23 November 2007;
accepted 8 July 2008.
Available online 18 July 2008.
Abstract
A variational approach to shape feature control in topology optimization is presented in this paper. The method is based on a new class of surface energies known as higher-order energies as opposed to the conventional energies for problem regularization, which are linear. In employing a quadratic energy functional in the objective of the topology optimization, non-trivial interactions between different points on the structural boundary are introduced, thus favoring a family of shapes with strip-like (or beam) features. In addition, the quadratic energy functional can be seamlessly integrated into the level set framework that represents the geometry of the structure implicitly. The shape gradient of the quadratic energy functional is fully derived in the paper, and it is incorporated in the level set approach for topology optimization. The approach is demonstrated with benchmark examples of structure optimization and compliant mechanism design. The results presented show that this method is capable of generating strip-like (or beam) designs with specified feature width, which have highly desirable characteristics and practical benefits and uniquely distinguish the proposed method.
Keywords: Shape feature control; The level set method; Structural topology optimization; Quadratic energy functional; Shape gradient
(a) 3D weighting function ψ.
(b) Its corresponding 2D slice.
Fig. 1. The weighting function ψ.
Fig. 2. Strip-like shapes caused by the quadratic energy functional.
(a) The implicit level set function.
(b) Its corresponding boundary.
Fig. 3. A 2d boundary embedded as the zero level set of a 3d level set function.
Fig. 4. Calculation of the boundary integration along piecewise line segments.
Fig. 5. The sketch of a two-bar cantilever.
Fig. 7. Boundary condition of the bridge beam.
(a) Without Eq.
(b) With Eq.
Fig. 8. Optimization of a bridge beam before (column (a)) and after (column (b)) using the quadratic energy functional.
Fig. 9. A schematic for the micro-gripper.
Fig. 10. Optimization results of the first case of a micro-gripper using the quadratic energy functional.
Fig. 11. Optimization results of the second case of micro-gripper using the quadratic energy functional.
Fig. 12. A lumped compliant mechanism with lumped compliance.
Table 1.
Parameters and figures of the optimization results of a two-bar cantilever

Table 2.
Parameters and figures of the optimization results of a bridge beam


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