Design and Analysis of Additively Manufactured Components with Integrated Lattice Structures

Abstract

Additive Manufacturing (AM) for metals is a fast growing field which is almost ready for industrialisation. Structural optimisation(SO) tools like Topology optimisation(TO) are now the most beneficial tools to the area of structural design. But, these tools give a design output that is very difficult to be manufactured by conventional manufacturing techniques like casting. This is where AM comes into the picture as it helps to overcome the rigid boundaries of other manufacturing methods due to its ability in helping produce objects of complex shapes and functionality. Lattice structures are very useful elements in structural design but are very difficult to produce by other methods , especially for the purpose as infill for objects. This gives an opportunity to use AM for producing objects with integrated lattice structure. The are various types of lattice structures like octet, gyroid etc. By properly aligning the lattice structure inside an object instead of completely filling it, structures with low density and weight can be achieved while also being strong. Lattice structures have been used as temporary support material for AM prints, but here they will also be a part of the final component itself serving as functional structures. This master thesis conducted at RISE IVF consists of first studying various types of self-supporting lattices and conducting virtual tests with regard to shear, tension, compression stresses etc. The second part of the thesis concerns topology optimization of a structural component design provided by Volvo Cars. This is done in order to get a design output that is suitable to be integrated with lattice structure to achieve lightweighting with minimal changes to the strength characteristics. A homogenized model is developed to verify the effects of the lattice unit cell in the optimized component. The final results of the linear analysis of the homogenized model was compared to the linear analysis of the steel sheet metal pivot bracket given by Volvo Cars. The final result comparison and analysis showed that the topology optimized pivot bracket component with integrated lattice structure was slightly lighter than the steel sheet metal pivot bracket designed by Volvo Cars and of comparable stiffness. This methodology allowed the authors to create a component design that is integrated with lattice structure and has a comparative stiffness design parameter of the original component. The design is also potentially manufacturable by AM, but the time limit prevented the actual printing process and hence all results were verified virtually. This methodology can be used for components that are fit for manufacturing via additive manufacturing for the purpose of lightweighting without much loss of structural integrity.