SACM - United Kingdom
Permanent URI for this collectionhttps://drepo.sdl.edu.sa/handle/20.500.14154/9667
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Item Restricted Layered Extrusion of engineering Metal Alloys (LEMA) using Semi-Solid Thixotropic Feedstock(The University of Sheffield, 2023-08-31) Alharbi, Abdullah; Mumtaz, KamranAdditive manufacturing (AM) has gained significant attention in low- and medium-volume industries due to its ability to create custom products with complex shapes, design freedom, material savings, and short lead times. While most AM processes focus on thermoplastics, there is increasing interest in metal AM systems, including powder bed fusion processes. However, these methods often involve high acquisition and operating costs, limiting accessibility. To address this, this study focuses on developing and investigating the Layered Extrusion of Engineering Metal Alloys (LEMA) system as a cost-effective alternative metal AM approach. The LEMA system manipulates alloys in the semi-solid thixotropic state. Utilising semi-solid metal slurry in extrusion-based AM can result in metal components with substantially lower operating costs and reduced thermal stresses compared to laser-based method. Experimental work initially conducted (Phase I) using the LEMA system involved in-situ creation of semi-solid thixotropic metallic alloys, particularly focusing on the Zn-Sn binary system, but improvements were made to the LEMA system for the subsequent phase to enhance performance. In Phase II, thermodynamic simulations and thermal analysis have indicated that Zn-40Sn holds promise for semi-solid thixotropic applications. Cold extrusion and heat treatment processes were employed to produce thixotropic feedstock with proper microstructures before being additively manufactured. The 3D printed components were evaluated and the result suggested that the adapted method for semi-solid billets preparation was feasible technique which then helped in a successful printing metallic material. Additionally, printing experiments were conducted to study the effects of major process parameters on the quality of deposited single-layer. It was demonstrated that single layers could be printed under 1.5 mm diameter orifice, extrusion speed of 20 mm/min, substrate moving velocity of 200 mm/min, and extrusion temperature of ≈313 ℃. The optimized printing process parameters from these experiments were then utilized for multilayer printing. It was found that substrate temperature is a key factor for achieving good metallurgical layer bonding at the interface of the printed layers. The research results support LEMA's feasibility as an alternative for the metal additive manufacturing route and lays the groundwork for processing SSMs with higher melting points in the future.4 0Item Restricted Design and rapid prototyping of orthopaedic device for lower limb fractures(The University of Manchester, 2024-05-31) Alqahtani, Mohammed; Bartolo, PauloBone fractures are a prevalent occurrence on a daily basis, posing significant challenges to healthcare systems in terms of hospital admissions, surgical procedures, and medication requirements. These fractures primarily result from either pathological conditions or highenergy trauma, including incidents such as car accidents, falls, and natural disasters. The treatment of bone fractures necessitates the use of bone fixation devices, which can be either internal or external, to provide stability to the injury, promote bone healing, and enable the patient to regain full functionality. The current designs of fixation devices, along with the materials utilised in their manufacturing, lead to fixators that are excessively heavy, lack comfort and lack of customisation to meet the unique requirements of individual patients. These concerns highlight the necessity of continued progress in the development of fixation devices to achieve improved and personalised medical treatments, with the aim of enhancing clinical outcomes and reducing costs. Therefore, the aim of this research project is to overcome the identified limitations by developing an innovative, customised, and optimised bone fixation system that is both costeffective and lightweight, while ensuring its structural integrity through the utilisation of topology optimisation, polymeric material and additive manufacturing. The bone fixation systems were successfully optimised, taking into consideration various loading conditions and mass reduction values. Fused deposition modelling additive manufacturing was employed to fabricate the optimised models. Subsequently, the bone fixation systems underwent numerical and mechanical evaluation and validation. The results indicate that an increase in mass reduction leads to higher stress and displacement, which can be attributed to material removal. Furthermore, it was observed that these optimised systems possess adequate mechanical characteristics, as evidenced by the IFM falling within the acceptable range and the stresses generated in the system remaining below the yield strength. This demonstrates the potential of utilising polymeric materials and topology optimisation in the development of bone fixation devices. This research presents a novel approach involving the use of polymeric materials and topology optimisation to create custom fixation devices tailored to individual patient anatomy. This is the first type of fixation that could represent a potential alternative to the existing conventional fixations, offering promising prospects.7 0