Abstract
The integration of topology optimization (TO) and additive manufacturing (AM) technologies can create significant synergy benefits, while the lack of AM-friendly TO algorithms is a serious bottleneck for the application of TO in AM. In this paper, a TO method is proposed to design self-supporting structures with an explicit continuous self-supporting constraint, which can be adaptively activated and tightened during the optimization procedure. The TO procedure is suitable for various critical overhang angles (COA), which is integrated with build direction assignment to reduce performance loss. Besides, a triangular directional self-supporting constraint sensitivity filter is devised to promote the downward evolution of structures and maintain stability. Two numerical examples are presented; all the test cases have successfully converged and the optimized solutions demonstrate good manufacturability. In the meanwhile, a fully self-supporting design can be obtained with a slight cost in performance through combination with build direction assignment.
Highlights
Additive manufacturing (AM) is a free-form manufacturing technique that builds parts in layers by depositing fine powder material, which is advantageous in building parts with complex shapes without specific tooling or fixturing [1]
A Topology optimization (TO) procedure of self-supporting structures that suitable for various critical overhang angles (COA) is proposed, which is integrated with build direction assignment to reduce performance loss caused by self-supporting constraint
A new adaptive explicit continuous self-supporting constraint function is constructed to quantify the degree of self-supporting constraint violation, which can be adaptively activated and tightened during the optimization process
Summary
Additive manufacturing (AM) is a free-form manufacturing technique that builds parts in layers by depositing fine powder material, which is advantageous in building parts with complex shapes without specific tooling or fixturing [1]. Within the SIMP framework, Serphos [9] integrated the geometrical restriction in the optimization process through three strategies: multiple objective functions, global explicit constraint and density filter. Wang et al [31] proposed a new form of overhang constraint in the level set framework, which is expressed as a single domain integral instead of point-wise constraints. Zhao et al [33] proposed a density filter within homogenization theory-based method to ensure that the porous structure satisfies the self-supporting constraint. Wang et al [34] presented a B-spline based method to design self-supporting structures, in which an overhang angle constraint and a triangle constraint are presented. A triangular directional self-supporting constraint sensitivity filter is proposed to promote the downward evolution of structures and maintain stability.
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