The topology optimization using isolines/isosurfaces and extended finite element method (Iso-XFEM) is an evolutionary optimization method developed in previous studies to enable the generation of high-resolution topology optimized designs suitable for additive manufacture. Conventional approaches for topology optimization require additional post-processing after optimization to generate a manufacturable topology with clearly defined smooth boundaries. Iso-XFEM aims to eliminate this time-consuming post-processing stage by defining the boundaries using isovalues of a structural performance criterion and an extended finite element method (XFEM) scheme. In this article, the Iso-XFEM method is further developed to enable the topology optimization of geometrically nonlinear structures undergoing large deformations. This is achieved by implementing a total Lagrangian finite element formulation and defining a structural performance criterion appropriate for the objective function of the optimization problem. The Iso-XFEM solutions for geometrically nonlinear test cases implementing linear and nonlinear modelling are compared, and the suitability of nonlinear modelling for the topology optimization of geometrically nonlinear structures is investigated.

This study investigates the fluid forces acting on a circular cylinder in a laminar flow regime while using a passive control strategy. Three cases including the cylinder with one, two or three rigid splitter plates attached at its rear surface were considered and the location of horizontal plates (attachment angle) was varied between 0° and 90°. A comprehensive parametric study was performed to identify the optimum arrangement of the plates using the commercial finite element software, Comsol Multiphysics. The results show that the location and the number of the plates have crucial effects on the wake control. Increasing the number of splitter plates from one to two symmetric parallel plates led to a reduction in drag force, vortex shedding frequency and fluctuation of lift force. A maximum drag reduction of 23% for dual-splitters and 15% for single-splitter was achieved, at an angle of 45° at Reynolds number 100. However, increasing the number of attached plates to three didn’t have a significant effect on flow quantities when plates of the same length were utilised. The suitability of the third plate (the middle plate) was further studied by investigating the effect of length of the plate on flow quantities.

This study presents the design and development of a 2D auxetic filtering medium with programmable geometric features specifically designed to vary under in-plane tensile strain. This feature empowers the filtering medium to control the particles separation. A novel design and optimisation algorithm developed in Matlab^® determines the final optimized geometry of the filtering medium based on the desired particle size input. Upon thorough numerical investigation, an empirical relationship between the linear elastic in-plane tensile strain and aperture size of the proposed metamaterial is revealed. This empirical relation can be used in mechatronic and control systems to steer the proposed filtering medium. A prototype of such filtering medium capable of classification of particles of size 4 mm to 4.5 mm, when subjected to linear strain, is fabricated through fused deposition modelling process. The developed geometry configurations in this research are scalable, providing a potential cost-effective and efficient solution for industrial applications including reconfigurable filtration and segregation systems.

As the understanding of disease grows, so does the opportunity for personalization of therapies targeted to the needs of the individual. To bring about a step change in the personalization of medical devices it is shown that multi‐material inkjet‐based 3D printing can meet this demand by combining functional materials, voxelated manufacturing, and algorithmic design. In this paper composite structures designed with both controlled deformation and reduced biofilm formation are manufactured using two formulations that are deposited selectively and separately. The bacterial biofilm coverage of the resulting composites is reduced by up to 75% compared to commonly used silicone rubbers, without the need for incorporating bioactives. Meanwhile, the composites can be tuned to meet user defined mechanical performance with ±10% deviation. Device manufacture is coupled to finite element modelling and a genetic algorithm that takes the user‐specified mechanical deformation and computes the distribution of materials needed to meet this under given load constraints through a generative design process. Manufactured products are assessed against the mechanical and bacterial cell‐instructive specifications and illustrate how multifunctional personalization can be achieved using generative design driven multi‐material inkjet based 3D printing.