414 Optimal Design of Softening-type Variable Stiffness Structure

The authors have proposed a concept of force dependent variable stiffness by introducing a certain internal gap in a continuum structure. This concept has been demonstrated to be valid for designing the structure of hardening-type bilinearity. This study discusses the design of continuum structure showing softening-type variable stiffness. Two different mean compliances are considered for a continuum structure at different ranges of external load divided by the stiffness switching level of working load. First, the compliant mechanism design problem is employed to obtain the initial design used for the following variable stiffness design. Second, the topology determination problem is formulated as the minimization of the structural volume under the constraints of prescribed mean compliances below and over the switching load level by using SIMP method. Third, the geometry determination problem is formulated based on the obtained topology, and is solved by the traction method. The effectiveness of the proposed design optimization problem is demonstrated through an example design problem.