Adedeji Aremu

The effects of bidirectional evolutionary structural optimization parameters on an industrial designed component for additive manufacture

An assessment of the effect of topology optimization design parameters on the performance of an additively manufactured part has been performed. The dependence of the output from a topology optimization involving an aerospace component on the topology optimization control parameters, evolution rate and filter radius was determined. The converged strain energy was found to depend quadratically on the filter radius while the number of iterations required to achieve a solution was broadly related to the evolution rate. These findings demonstrate the potential for significant design efficiencies when manufacturing using additive manufacturing approaches but also the need to be aware of the sensitivity of the bidirectional evolutionary structural optimization optimized design on the selected optimization parameters. This sensitivity can potentially be used advantageously to steer the solution to an optima with features suitable to a particular manufacturing method such as additive manufacturing.

An investigation into reinforced and functionally graded lattice structures

Lattice structures are regarded as excellent candidates for use in lightweight energy-absorbing applications, such as crash protection. In this paper we investigate the crushing behaviour, mechanical properties and energy absorption of lattices made by an additive manufacturing process. Two types of lattice were examined: body-centred-cubic (BCC) and a reinforced variant called BCC z . The lattices were subject to compressive loads in two orthogonal directions, allowing an assessment of their mechanical anisotropy to be made. We also examined functionally graded versions of these lattices, which featured a density gradient along one direction. The graded structures exhibited distinct crushing behaviour, with a sequential collapse of cellular layers preceding full densification. For the BCC z lattice, the graded structures were able to absorb around 114% more energy per unit volume than their non-graded counterparts before full densification, 1371 ± 9 kJ/m3 versus 640 ± 10 kJ/m3. This highlights the strong potential for functionally graded lattices to be used in energy-absorbing applications. Finally, we determined several of the Gibson–Ashby coefficients relating the mechanical properties of lattice structures to their density; these are crucial in establishing the constitutive models required for effective lattice design. These results improve the current understanding of additively manufactured lattices and will enable the design of sophisticated, functional, lightweight components in the future.

Effects of Net and Solid Skins on Self-Supporting Lattice Structures

Multi-functional capabilities of Lattice materials allow them to be used in weight bearing applications, impact absorption and heat dissipation. Previously, the range of cellular materials was limited by constraints in traditional manufacturing technologies. This situation has been mitigated by advances in additive manufacturing (AM) techniques, which allows the manufacture of complex parts directly from three dimensional CAD models. However, other manufacturing difficulties emerge with AM techniques. Such difficulties exist with metallic components produced with selective laser melting (SLM). The need for support could compromise the quality of the lattice being built since it is difficult to remove such structures. Lattices requiring little or no support are better suited for SLM. A method was recently developed to fit such lattices to complicated three dimensional domains and consist of an approach to improve the performance of the trimmed lattices with solid and net skins. In this paper, we investigate the influence of these skins on the stiffness of Body-Centred Cubic (BCC) and Double-Gyroid (Dgyroid) lattices via finite element analysis. Including a net skin on the BCC lattice improved its stiffness as the thickness of the skin was increased. The stiffness of Dgyroid lattice was insensitive to a net skin. However, solid skins improve the performance of both lattice types.

Non-linear Contact Analysis of Self-Supporting Lattice

Using additive manufacturing (AM) techniques for end user parts is quite attractive for performance enhancement and product customization since designs are less constrained via this technique. The extent to which this could influence design is still to be determined. An interesting way to exploit AM capabilities for mechanical components is to embed lattice structures in such components. However, constraints inherent on some AM machines might limit the range of suitable lattices. For selective laser melting (SLM), supports are needed for features inclined at an angle lower than 45∘. This does imply that lattices without such features are better suited for SLM. Despite this constraint, a number of lattices can be made via the SLM technique. In this paper, we determine the structural properties of four of these self-supporting lattices via non-linear contact analysis. A minimal surface lattice show superior properties to those of the other three strut based lattices.