Topology optimization of compliant mechanisms with strength considerations

Multicriteria formulations that have been reported previously in topology d esign of compliant mechanisms address flexibility and stiffness issues simu ltaneously and aim to attain an optimal balance between these two conflicti ng attributes. Such techniques are successful in indirectly controlling the local stress levels by constraining the input displacement. Individual con trol on the conflicting objectives is often difficult to achieve with these flexibility-stiffness formulations. Resultant topologies may sometimes be overly stiff, and there is no guarantee against failure. Local stresses may exceed the permissible yield strength of the constituting material in such designs. In this article, local failure conditions relating to stress cons traints are incorporated in topology optimization algorithms to obtain comp liant and strong designs. Quality functions are employed to impose stress c onstraints on retained material, ignoring nonexisting regions in the design domain. Stress constraints are further relaxed to regularize the design sp ace to help the mathematical programming algorithms based on the Karush-Kuh n-Tucker conditions yield improved solutions. Examples are solved to corrob orate the solutions for failure-free compliant topologies that are much imp roved in comparison to those obtained using flexibility-stiffness multicrit eria objectives.