Force-Dependent Bilinear Variable Stiffness Design of Continuum Structure.

Abstract

Stiffness is one of fundamental properties in structural design, such as in maximum stiffness design. The nonlinear structural property is an attractive characteristic to be designed although majority of structural design problem deals with the linear elastic property. This article discusses the concept of force-dependent variable stiffness. The mean compliance measures the structural stiffness from the viewpoint of external load and the deformation at the loading sight. A certain gap is introduced as an internal boundary in the continuum structure, and its open/close status may depend on working force condition. Such a gap is expected to work as the switching mechanism, which brings the force-dependent variable stiffness. The attention is forced on the bilinear stiffness design having only one switching point of stiffness in the context of structural topology and geometry determination. First, the topology determination problem is formulated by using SIMP method and solved by sequential linear programming supported by moving limit strategy. Second, the geometry determination problem is formulated based on the topology obtained under the constraints of bilinear stiffness with the specified external load for stiffness switching, and is solved by the traction method. A couple of numerical cases studies demonstrated the feasibility and effectiveness of the proposed design concepts.