A level set-based optimized design of multi-material compliant mechanisms considering stress constraints

• Published in: Computer methods in applied mechanics and engineering Vol. 391; p. 114556
• Main Authors: Emmendoerfer, Hélio, Maute, Kurt, Fancello, Eduardo Alberto, Silva, Emílio Carlos Nelli
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.03.2022; Elsevier BV
• Subjects: Compliant mechanism; Constraint modelling; Design optimization; Level sets; Multi-material; Stress constraints; Topology; Topology optimization; Compliant mechanism; Topology optimization; Stress constraints; Level sets; Multi-material
• ISSN: 0045-7825
• DOI: 10.1016/j.cma.2021.114556

This work presents a level set-based approach to design multi-material compliant mechanisms subject to local stress constraints. The inclusion of stress constraints can avoid non-realistic hinges formed by a single node or element often present in compliant mechanisms. This study proposes an optimization procedure capable of assigning multiple materials with distinct properties along the structure to obtain mechanisms that maximize the output displacement and satisfy stress constraints. For the level set topology description, the Multi-Material Level Set (MM-LS) model is adopted. Local stress constraints and volume constraints for the multiple material phases are included in the objective function via an augmented Lagrangian technique. The structural geometry is defined by an explicit level set method and the Ersatz material model. The proposed approach is presented in a generalized form that can be easily extended to any number of materials defined by the user. Two-dimensional numerical results demonstrate the efficacy of the proposed procedure. •Procedure to design multi-material compliant mechanisms with stress constraints.•An augmented Lagrangian approach is used to handle local stress constraints.•Explicit level set method and Ersatz material model define the structural geometry.•Hinge-free designs with multiple phases are obtained.•Design feasibility is numerically validated with a commercial FEM code.