Casting of topologically optimized components utilizing additive manufacturing

Casting is a widely-used metalworking method that is valued for its benefits in product manufacturability, repeatability, versatility, and low cost. Although casting capabilities are always improving, there are still many limitations in component design due to the constraints of conventional pattern fabrication methods. Topology optimization is an innovative design approach that optimizes the material layout of the designated geometry. Optimized designs are often too complex to manufacture with standard casting, machining, or other fabrication processes, forcing the utility of topology optimization to remain solely in preliminary design. These designs often require alteration to improve manufacturability, therefore diminishing the full potential benefits of the topology optimization. Additive manufacturing (AM) technologies, such as 3D printing, are capable of fabricating topologically optimized components without design alteration. However, the limited material selection offered by 3D printers inhibits the performance of printed components. Combining AM technologies and casting allows the possibility to manufacture topologically optimized components using typical casting alloys. This work looks at current casting and AM technologies, the background of topology optimization, practical work on numerous original optimized designs, the adaption of selected designs to casting methodology, analysis of selected designs using casting simulations, and fabrication of selected designs via investment casting and sand mold casting. Results showed that the collaboration of casting and AM technologies allowed the fabrication of topologically optimized components without the need for significant design alteration. However, defects such as porosity and cracking occurred in both the simulations and physical castings of the components. These complications were likely caused by large variance in the size of adjacent features and by the presence of many flow fronts during pouring. Findings in this work highlight at least the following; optimized components can be produced by casting, although the methods and software need to develop further before the full potential of this approach can be reached. These issues could be mitigated through further study and optimization of the casting processes

Design and Development of a Lorentz Force-Based MRI-Driven Neuroendoscope

The introduction of neuroendoscopy, microneurosurgery, neuronavigation, and intraoperative imaging for surgical operations has made significant improvements over other traditionally invasive surgical techniques. The integration of magnetic resonance imaging (MRI)-driven surgical devices with intraoperative imaging and endoscopy can enable further advancements in surgical treatments and outcomes. This work proposes the design and development of an MRI-driven endoscope leveraging the high (3-7 T), external magnetic field of an MR scanner for heat-mitigated steering within the ventricular system of the brain. It also demonstrates the effectiveness of a Lorentz force-based grasper for diseased tissue manipulation and ablation. Feasibility studies show the neuroendoscope can be steered precisely within the lateral ventricle to locate a tumor using both MRI and endoscopic guidance. Results also indicate grasping forces as high as 31 mN are possible and power inputs as low as 0.69 mW can cause cancerous tissue ablation. These findings enable further developments of steerable devices using MR imaging integrated with endoscopic guidance for improved outcomes

A review on recent developments in binder jetting metal additive manufacturing: materials and process characteristics

Binder Jetting Metal Additive Manufacturing (BJ-MAM), known also as metal 3D-printing, is a powder bed-based additive manufacturing technology. It consists of the deposition of liquid binder droplets to selectively join powder particles to enable the creation of near-net shaped parts, which subsequently are consolidated via sintering process. This technology is known for its capability to process a wide range of different materials and for its orientation towards large volume production series. Binder Jetting has recently been drawing the attention of both the research sphere as well as several industrial sectors. The present review study encompasses the various and most remarkable aspects of BJ-MAM part fabrication. The review covers the material selection and characterisation considerations, followed by the manufacturing process features and the parameter effect on different part properties. It concludes with an overview concerning the most recent case studies with regards to diverse metal alloy developments.This work has been done within the ADDISEND project supported by the ELKARTEK program of the Basque Government [KK-2018/00115]

Benchmarking of Extrusion Based Additive Manufacturing Processes

The main purpose of this thesis is to contribute filling this knowledge gap to help user making a more informed decision on process selection and gain more confidence on using AM technologies. The work is especially going to focus on extrusion-based systems due to its common use and availability.openEmbargo temporaneo per motivi di segretezza e/o di proprietà dei risultati e/o informazioni sensibil