Topology synthesis of electrothermal compliant mechanisms using line elements

This paper presents a line-element-based approach to the topology synthesis of electrothermal compliant (ETC) mechanisms. A line element is a one-dimensional model of the electrical, thermal, and elastic behavior of a beam-like continuum. In contrast to topology synthesis of ETC mechanisms by a continuum-element-based approach, the line-element-based approach offers significant conceptual and practical advantages. The line element allows for straightforward modeling of surface heat transfer in the topology optimization framework. It also obviates the need to interpolate electrical and thermophysical properties in the topology synthesis procedure. Moreover, this approach results in clean geometries that are easy to fabricate directly in their optimized form. Solutions obtained from this procedure are compared with results from continuum-based optimal synthesis procedures as well as intuitive designs reported in the literature. A number of design examples are used to demonstrate the ability of the procedure to generate nonintuitive topologies. The synthesis procedure is also used to study the influence of the direction of output and the electrical and thermal resistance of the workpiece on the resulting optimal topologies.