Official ASME Group

Journal of Mechanical Design

The ASME Journal of Mechanical Design (JMD) serves the broad design community as a venue for scholarly, archival research in all aspects of the design activity.
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  • COMPARING STRATEGIES FOR TOPOLOGIC AND PARAMETRIC RULE APPLICATION IN AUTOMATED COMPUTATIONAL DESIGN SYNTHESIS

    ​Computational Design Synthesis (CDS) methods can be used to enable the computer to generate valid and even creative solutions for engineering tasks. In grammatical approaches to CDS, formal grammars are used to represent a desired design language. This language consists of vocabulary that usually describes components and subsystems of a design and a set of grammar rules that describe possible design transformations. The formalized engineering knowledge can then be used by the computer to synthesize designs. For most engineering tasks, two different kinds of rules are required: rules that change the topology of a design, i.e. how the components are connected, and rules that change parameters of a design. One of the main challenges in CDS using topologic and parametric grammar rules is to decide a priori which type of rule to apply in which stage of the synthesis process as well as whether to start from a valid design and perturb it or to start from a void design. The research presented in this paper compares different strategies for topologic and parametric rule applications during automated design synthesis driven by a search algorithm. The presented strategies are compared considering quantity and quality of the generated designs. The effect of the strategies, the selected search algorithm, and the initial design, from which the synthesis is started, are analyzed for two case studies: the synthesis of gearboxes and of bicycle frames. Results show that the effect of the strategy is dependent on the design task and recommendations are given on which strategies to use for which design task.
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  • LEVEL SET TOPOLOGY OPTIMIZATION OF PRINTED ACTIVE COMPOSITES

    Kurt MauteAnton TkachukJiangtao WuH. Jerry QiZhen Ding and Martin L. Dunn
    J. Mech. Des 137(11), 111402; doi: 10.1115/1.4030994
    Multi-material polymer printers allow the placement of different materials within a composite. The individual material phases can be spatially arranged and shaped in an almost arbitrary fashion. Utilizing the shape memory behavior of at least one of the material phases, active composites can be 3D printed such that they deform from an initially flat plate into a curved structure. To navigate this vast design space, systematically and efficiently explorer design options, and find an optimum layout of the composite this paper presents a novel design optimization approach. The optimization approach combines a level set method for describing the material layout and a generalized formulation of the extended finite element method (XFEM) for predicting the response of the printed active composite (PAC). This combination of methods yields optimization results that can be directly printed without the need for additional post-processing steps. The proposed optimization method is studied with examples where the target shapes correspond to a plate-bending type deformation and to a localized deformation. The optimized designs are 3D printed and the XFEM predictions are compared against the experimental measurements. The design studies demonstrate the ability of the proposed optimization method to yield a crisp and highly resolved description of the optimized material layout that can be realized by 3D printing.
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  • TOWARD A UNIFIED DESIGN APPROACH FOR BOTH COMPLIANT MECHANISMS AND RIGID-BODY MECHANISMS: MODULE OPTIMIZATION

    J. Mech. Des 137(12), 122301; doi: 10.1115/1.4031294
    Rigid-body mechanisms (RBMs) and compliant mechanisms (CMs) are traditionally treated in significantly different ways. In this paper, we present an approach to the synthesis of both RBMs and CMs. In this approach, RBMs and CMs are generalized into mechanisms that consist of five basic modules, including Compliant Link (CL), Rigid Link (RL), Pin Joint (PJ), Compliant Joint (CJ), and Rigid Joint (RJ). The link modules and joint modules are modeled with beam and hinge elements, respectively, in a geometrically nonlinear finite element solver, and subsequently a discrete beam-hinge ground structure model is established. Based on this discrete beam-hinge model, a procedure that follows topology optimization is developed, called module optimization. Particularly, in the module optimization approach, the states (both presence or absence and sizes) of joints and links are all design variables, and one may obtain a RBM, a partially CM, or a fully CM for a given mechanical task. The proposed approach has thus successfully addressed the challenge in the type and dimensional synthesis of RBMs and CMs. Three design examples of the path generator are discussed to demonstrate the effectiveness of the proposed approach.
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