A modified stiffness spreading method for layout optimization of truss structures

The stiffness spreading method (SSM) was initially proposed for layout optimization of truss structures, in which an artificial elastic material of low modulus is uniformly distributed in the design domain to create connections between discrete members. In this paper, a modified stiffness spreading method is proposed by replacing the artificial elastic material with auxiliary bars to connect real members of the truss structure. Since the background continuum mesh for the elastic material is no longer required, the computational cost is significantly reduced. Like SSM, the new method is advantageous in that an initial design may consist of disconnected bars allocated in the design domain, and mathematical programming methods can be applied for the efficient solution of the formulated optimization problem. A number of solution strategies are also developed to achieve more practical designs with lower computational cost. Numerical examples of both 2-D and 3-D truss structures are presented to demonstrate the feasibility, robustness and effectiveness of the proposed method.