Optimization strategies for discrete multi-material stiffness optimization

  • Authors:
  • Christian Frier Hvejsel;Erik Lund;Mathias Stolpe

  • Affiliations:
  • Department of Mechanical and Manufacturing Engineering, Aalborg University (AAU), Aalborg Øst, Denmark 9220;Department of Mechanical and Manufacturing Engineering, Aalborg University (AAU), Aalborg Øst, Denmark 9220;Department of Mathematics, Technical University of Denmark (DTU), Kgs. Lyngby, Denmark 2800

  • Venue:
  • Structural and Multidisciplinary Optimization
  • Year:
  • 2011

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Abstract

Design of composite laminated lay-ups are formulated as discrete multi-material selection problems. The design problem can be modeled as a non-convex mixed-integer optimization problem. Such problems are in general only solvable to global optimality for small to moderate sized problems. To attack larger problem instances we formulate convex and non-convex continuous relaxations which can be solved using gradient based optimization algorithms. The convex relaxation yields a lower bound on the attainable performance. The optimal solution to the convex relaxation is used as a starting guess in a continuation approach where the convex relaxation is changed to a non-convex relaxation by introduction of a quadratic penalty constraint whereby intermediate-valued designs are prevented. The minimum compliance, mass constrained multiple load case problem is formulated and solved for a number of examples which numerically confirm the sought properties of the new scheme in terms of convergence to a discrete solution.