Topology optimization of nonlinear periodically microstructured materials for tailored homogenized constitutive properties

A topology optimization method is presented for the design of periodic microstructured materials with prescribed homogenized nonlinear constitutive properties over finite strain ranges. The mechanical model assumes linear elastic isotropic materials, geometric nonlinearity at finite strain, and a quasi-static response. The optimization problem is solved by a nonlinear programming method and the sensitivities computed via the adjoint method. Two-dimensional structures identified using this optimization method are additively manufactured and their uniaxial tensile strain response compared with the numerically predicted behavior. The optimization approach herein enables the design and development of lattice-like materials with prescribed nonlinear effective properties, for use in myriad potential applications, ranging from stress wave and vibration mitigation to soft robotics

Level set topology optimization for design dependent hydrostatic loading using the reproducing kernel particle method

Level set topology optimization for the design of structures subjected to design dependent hydrostatic loads is considered in this paper. Problems involving design-dependent loads remain a challenge in the field of topology optimization. In this class of problems, the applied loads depend on the structure itself. The direction, location and magnitude of the loads may change as the shape of the structure changes throughout optimization. The main challenge lies in determining the surface on which the load will act. In this work, the reproducing kernel particle method (RKPM) is used in combination with the level set method to handle the dependence of loading by moving the particles on the structural boundary throughout the optimization process. This allows for the hydrostatic pressure loads to be applied directly on the evolving boundary. One-way fluid-structure coupling is considered here. A hydrostatic pressure field governed by Laplace’s equation is employed to compute the pressure acting on linear elastic structures. The objective in this optimization problem is to minimize compliance of these structures. Numerical results show good agreement with those in the literature

Topology optimization of vibrational piezoelectric energy harvesters for structural health monitoring applications

Aircraft structures exhibit localized vibrations over a wide range of frequencies. Such vibrations can be used to power sensors which then monitor the health of the structure. Conventional vibrational piezoelectric harvesting involves optimizing the harvester for one distinct frequency. The aim of this work is to design a wireless vibrational piezoelectric system capable of energy harvesting in the range of 100–500 Hz by tailoring the resonant behavior of cantilever structures. We herein employ a model capable of predicting the performance of a piezoelectric cantilever retrofit on a structural health monitoring sensor and then formulate a design optimization problem and solve with the level set topology optimization method. The designs are verified through fabrication of experimental prototypes