Edinburgh Napier University

  Topology optimization technique has been used as an efficient tool that optimizes material layout within a given space to obtain the desired functional performance. So far, topology optimization has been mainly focused on linear problems and less attention has been paid on nonlinear design, although accounting for the material nonlinearity can significantly influence the optimized structure layout.

Research studies undertaken in this thesis considered material elastoplasity in combination with the SIMP based topology optimization method, particularly for two-phase structure in which different plastic material model is adopted for each phase. This expands the optimization scope in nonlinear design in further applications.

Since the structural nested framework that nonlinear analysis is repeatedly solved for every updated topology, is very computationally expensive. This research also proposed to apply the transient coupled nonlinear system to BESO method for nonlinear structural design, as a result, a stable topological evolution was achieved, and results converged after a much smaller number of iterations.

In addition, this research originally proposed a topology optimization method for plastic strain minimization design, to accommodate the diverse design purpose. By means of several examples of equivalent plastic strain minimization, in comparison with the results obtained from the elastic stiffness-based design, elastoplastic stiffness-based design,
it is revealed that materials are much more efficiently used, and the plastic strain and von Mises stress are more evenly distributed within the design domain.