An Effective Method of Synthesizing Compliant Adaptive Structures using Load Path Representation

Abstract

The synthesis of shape morphing compliant mechanism is inherently different from the typical single output design problems, due to the multiple output points along the morphing boundary. We have previously developed a genetic algorithm (GA)-based synthesis approach, incorporating a binary ground structure parameterization, to systematically design shape morphing compliant mechanisms. However, the approach is ineffective due to issues such as the generation of disconnected structures and the need to choose an initial mesh. In this paper, we present the ‘load path representation,’ which is developed to overcome the issues encountered using the binary ground structure parameterization. The performance of the load path approach over the binary ground structure approach is demonstrated through several design examples. The results have shown that the load path approach offers several advantages, such as (a) eliminating the need of an initial ground structure, (b) ensuring structural connectivity, and (c) yielding solutions that generate desired shape change efficiently.

Topological Optimization of Compliant Adaptive Wing Structure

“…In the load-path method an initial structural network of given topology is specified and an optimal structure is sought, whose topology is a subset of the original [4,8]. This means that the general structural form is already specified at the beginning of the design process, and therefore minimal postprocessing is required to realize a structure designed by this method, in contrast to the density-based approach, where the material is uniformly distributed at the beginning.…”

“…2. This is the starting point for the design process [4,8]. The design space is the region within which the optimized structure must be constrained.…”

“…For this reason computational topology optimization schemes are adopted. The primary optimization technique that will be used follows the load-path technique proposed by Lu and Kota [4] and requires that an initial lattice-structure topology be defined prior at the outset. A genetic algorithm is then used to determine which members should be present in the final optimum topology, which will be a subset of the originally defined topology.…”

Evaluation of a Compliant Droop-Nose Morphing Wing Tip via Experimental Tests

“…The use of heuristic evolutionary methods such as the load path representation method [9] is also a viable option and may lead to a more integrated design chain in which the skin, compliant mechanism and actuation system are designed concurrently rather than sequentially. The heuristic nature eliminates the need for the calculation of sensitivities which may be difficult to obtain for such morphing problems.…”

“…An even further subset of morphing technology is the use of compliant mechanisms as carefully arranged flexible substructures supporting and driving the smooth skin. These mechanisms hold high potential for use in morphing systems given the benefits over conventional sliding/pinned/rigid-link mechanisms of reduced wear, easier assembly, and the elimination of backlash [8][9][10][11].…”