Using Literature Reviews as a Learning Tool for Solid Freeform Fabrication

Over the past six years, students involved in the “Non-Traditional & Additive Manufacturing” course at Utah State University have been assigned an in-depth literature review as one their course projects. This literature review, done in groups of 2 or 3 students, involves becoming an expert on a topic of interest to the students and then presenting this material to the class as an indepth, oral presentation in addition to writing a journal-like review article on the topic. This project has proved to be a consistently effective method for enhancing learning of SFF technologies and their applications, and has been consistently noted by students in their course evaluations as a highly effective teaching tool. The methodology used for assigning and assessing these projects will be explored, in addition to a discussion of the benefits of this project toward meeting ABET criteria for accreditation of engineering programs.Mechanical Engineerin

Development of a Co-Cr-Mo to Tantalum Transition using LENS for Orthopedic Applications

Biomedical implant material research using additive manufacturing is a popular field of study. Many potential material combinations exist which, if implemented properly, could have a significantly positive effect on implant life and functionality. One material combination of interest is attaching porous Ta bone ingrowth material to a CoCrMo corrosion and wear resistant bearing surface. An investigation of the ability of the LENS process to join Ta to CoCrMo was undertaken. Direct joining of CoCrMo to Ta was known to be problematic, and thus transitional layers of other biomedically-compatible materials were investigated. It was determined that a transitional layer of zirconium appeared to be the best transitional material for this application due to its excellent biocompatibility, followed by stainless steel, with a lesser biocompatibility but better adhesive properties.Mechanical Engineerin

Transport improvement, commuting costs, and residential location

A theoretical framework for evaluating the effects of introducing new transportation on residential travel patterns is presented. Data are based on changes in residential location of urban commuters that alter the mode and length of work trips as well as economic factors

Multi-Material Ultrasonic Consolidation

Ultrasonic consolidation (UC) is a recently developed direct metal solid freeform fabrication process. While the process has been well-demonstrated for part fabrication in Al alloy 3003 H18, including with intricate cooling channels, some of the potential strengths of the process have not been fully exploited. One of them is its flexibility with build materials and the other is its suitability for fabrication of multi-material and functionally graded material parts with enhanced functional or mechanical properties. Capitalizing on these capabilities is critical for broadening the application range and commercial utilization of the process. In the current work, UC was used to investigate ultrasonic bonding of a broad range of engineering materials, which included stainless steels, Ni-base alloys, brass, Al alloys, and Al alloy composites. UC multimaterial part fabrication was examined using Al alloy 3003 as the bulk part material and the above mentioned materials as performance enhancement materials. Studies were focused on microstructural aspects to evaluate interface characteristics between dissimilar material layers. The results showed that most of these materials can be successfully bonded to Al alloy 3003 and vice versa using the ultrasonic consolidation process. Bond formation and interface characteristics between various material combinations are discussed based on oxide layer characteristics, material properties, and others.Mechanical Engineerin

A Motion Planning Approach for Fabrication of Complex 3-D Shapes in a LENS� Process

This paper discusses an approach for planning the motion of the laser deposition head relative to the part for fabrication of complex 3-D shapes such as parts with overhangs, branches, and internal cavities in direct metal deposition processes such as the LENS‘ process. The proposed approach is based on slicing the solid model of the part into equal-thickness slices perpendicular to the normal build direction and formulating a motion planning strategy based on the properties of these slices. The paper discusses the four sub-approaches that are proposed to handle a variety of complex 3-D shapes parts.Mechanical Engineerin

Deposition of Ti/TiC Composite Coatings on Implant Structures Using Laser Engineered Net Shaping

A new method of depositing hard and wear resistant composite coatings on metal-onmetal bearing surfaces of titanium implant structures is proposed and demonstrated. The method consists of depositing a Ti/TiC composite coating (~ 2.5 mm thick) on titanium implant bearing surfaces using Laser Engineered Net Shaping (LENS®). Defect-free composite coatings were successfully produced at various amounts of the reinforcing TiC phase with excellent interfacial characteristics using a mixture of commercially pure Ti and TiC powders. The coatings consisted of a mixture of coarser unmelted/partially melted (UMC) TiC particles and finer, discreet resolidified (RSC) TiC particles uniformly distributed in the titanium matrix. The amounts of UMC and RSC were found to increase with increasing TiC content of the original powder mixture. The coatings exhibited a high level of hardness, which increased with increasing TiC content of the original powder mixture. Fractographic studies indicated that the coatings, even at 60 vol.% TiC, do not fail in a brittle manner. Various aspects of LENS® deposition of Ti/TiC composite coatings are addressed and a preliminary understanding of structure-property-fracture correlations is presented. The current work shows that the proposed approach to deposit composite coatings using laser-based metal deposition processes is highly-effective, which can be readily utilized on a commercial basis for manufacture of high-performance implants.Mechanical Engineerin

Integration of Direct-Write (DW) and Ultrasonic Consolidation (UC) Technologies to Create Advanced Structures with Embedded Electrical Circuitry

In many instances conductive traces are needed in small, compact and enclosed areas. However, with traditional manufacturing techniques, embedded electrical traces or antenna arrays have not been a possibility. By integrating Direct Write and Ultrasonic Consolidation technologies, electronic circuitry, antennas and other devices can be manufactured directly into a solid metal structure and subsequently completely enclosed. This can achieve a significant reduction in mass and volume of a complex electronic system without compromising performance.Mechanical Engineerin

Improving Linear Weld Density in Ultrasonically Consolidated Parts

Ultrasonic consolidation is a novel additive manufacturing process with immense potential for fabrication of complex shaped three-dimensional metallic objects from metal foils. The proportion of bonded area to unbonded area along the layer interface, termed linear weld density (LWD), is perhaps the most important quality attribute of ultrasonically consolidated parts. Part mechanical properties largely depend on LWD and a high level of LWD must be ensured in parts intended for load-bearing structural applications. It is therefore necessary to understand what factors influence LWD or defect formation and devise methods to enhance bond formation during ultrasonic consolidation. The current work examines these issues and proposes strategies to ensure near 100% LWD in ultrasonically consolidated aluminum alloy 3003 parts. The work elucidates the effects of various process parameters on LWD and a qualitative understanding of the effects of process parameters on bond formation during ultrasonic consolidation is presented. The beneficial effects of using elevated substrate temperatures and its implications on overall manufacturing flexibility are discussed. A preliminary understanding of defect morphologies and defect formation is presented, based on which a method (involving surface machining) for minimizing defect incidence during ultrasonic consolidation is proposed and demonstrated. Finally, trade-offs between part quality and build time are discussed.Mechanical Engineerin