Multiple-layer Lamina Emergent Mechanisms (MLEMs) are mechanisms made from multiple sheets (lamina) of material with motion that emerges out of the fabrication plane. This study has shown that understanding how layers are used in existing products and in nature provides insight into how MLEMs can also use layers to achieve certain tasks. The multi-layered nature of MLEMs and the interactions between these layers are what enhance the capabilities of MLEMs and allow them to better meet design objectives. Layer separation is one objective for which MLEMs are well-suited. Layer separation can have a variety of applications and there are a number of different ways to design a MLEM to achieve this objective. Single-layer LEM and MLEM designs could greatly benefit from suitable actuation techniques; those that are consistent with the advantages of these mechanisms and could be incorporated into their design. This work presents shape memory alloys, piezoelectrics and dielectric elastomers as suitable ways of actuating LEMs and MLEMs. A number of novel MLEMs are presented throughout this thesis.

A wind tunnel investigation of an axisymmetric bluff body, known as a Goldschmied propulsor, was completed. This model conceptually combines boundary layer control and boundary layer ingestion into a single complementary system that is intended to use energy to reduce the axial force on the body by eliminating separation and increasing the pressure recovery aft of the body’s maximum thickness. The goal of the current project was to design, fabricate, and fully document the performance of a wind tunnel model incorporating the Goldschmied propulsor concept and complete an examination of its aerodynamic performance. The investigation took place at California Polytechnic State University, San Luis Obispo in the Aerospace Engineering Department’s subsonic 3ft by 4ft wind tunnel. The model is 38.5 inches in length and 13.5 inches in diameter with a discrete suction slot at 85% of the body length and an embedded propulsor that provides the suction flow, expelling it out of the model’s aft end. The experiment included measurements of surface pressure, total axial force, suction mass flow rate, fan thrust, fan torque, fan speed, and input fan power. The size of the suction slot and amount of input fan power were the main test variables in the 54 data point test matrix that was completed at a length Reynolds number of 1.34 million and a tunnel speed of 66 ft/s (20 m/s). The model was able to achieve fully attached flow on the aftbody with as little as 100W of input power and a net positive (forward) axial force coefficient of 0.12 with as little as 200W of input power. The model was also able to achieve a peak axial pressure force coefficient of 0.005 in the forward direction with an input power of 500W and a slot gap of 1.6% of the body length. A slightly lower axial pressure force coefficient of 0.0045 was achieved with only 200W of input power and a slot gap of 0.7% of the body length. The peak axial pressure force for most tested slot gaps occurred at about 200W of input power, and a slot gap of 0.7% of the body length resulted in the best overall performance for most input power settings. Two different suction slot configurations, a simple gap and a cusp, were tested, and no significant performance differences were seen between them. The pressure coefficient data showed similar trends as test data from 1956 of a similar model at higher Reynolds number, but it did not show complete agreement. Despite these positive aspects of the investigation, a simple power based comparison between the collected data and a conventional non-integrated propulsor does not show a performance improvement for the Goldschmied propulsor.

Published Article / A component, which has a perfect combination of different materials (probably including homogeneous materials and three different types of heterogeneous materials) in its different portions for a specific application, is considered as the component made of a multiphase perfect material. To fabricate such components, a hybrid layered manufacturing process has been developed. In order to accurately spray different materials with their required volume fractions for every pixel during fabrication, it is important to investigate its spraying operation. This paper establishes the behavior model of the spraying device and proves its validity using digital simulations.

Published Article / Extensive work has been done in the area of manufacturing implants for medical purposes, and more recently the development of customised implants. Areas of application include cranio/maxillo-facial implants, dental drill guides, hip, knee and shoulder replacements, as well as different implants for the spine. Due to their high prevalence and complex anatomical geometry the purpose of this study is to investigate the current state of the industry regarding customised medical implants for cranio/maxillofacial and orthopaedic surgery. Implant customisation has far-reaching benefits, and a collective approach to solving current difficulties will require an in-depth study of successes already achieved. Several issues in this regard are examined, including what defines customisation, regulatory issues that govern customisation and design constraints, trends in different areas of application, suitable materials, and finally which manufacturing techniques are being employed, with a focus on the use of Layer Manufacturing technologies and their role in custom-made medical implants.

Published Article / Current fused deposition modelling (FDM) technologies deposit material as flat layers. The result is a "stair-case" effect on non-vertical or horizontal surfaces, and compromised part strength because of weakness between the laminations. This paper describes an FDM method through which layers of build material are deposited as curved layers following the shape of the part, thus removing the stair-case effect and creating parts that have an even strength distribution over their entire surface. Support material is first deposited as conventional flat layers, and build material is then deposited over the support structure following the curves of the part. The paper discusses a proof of concept of the system, the algorithms used to generate the curve paths for the deposition head, and examines the challenges and possibilities of this technology, including the capability of including composite materials.

ITC/USA 2008 Conference Proceedings / The Forty-Fourth Annual International Telemetering Conference and Technical Exhibition / October 27-30, 2008 / Town and Country Resort & Convention Center, San Diego, California / Synchronization of the iNET communication link is essential for implementing the TDMA channel access control functions within the transceiver MAC transport layer, and providing coherent signal demodulation timing at the transceiver PHY layer. In the following implementation, the 1588 timing reference source is the GPS receiver. Because it is being used in the Ground Station Segment and Test Article Segment, it becomes feasible to utilize the 1588 timing reference for cross-layer (MAC+PHY) iNET transceiver synchronization. In this paper, we propose an unified iNET transceiver synchronization architecture to improve iNET transceiver performance. The results of the synchronization performance analysis are given.

ITC/USA 2008 Conference Proceedings / The Forty-Fourth Annual International Telemetering Conference and Technical Exhibition / October 27-30, 2008 / Town and Country Resort & Convention Center, San Diego, California / Unlike communications protocols that are bus-based or multi-drop (e.g., CAIS Bus, Fibre Channel, RS-485), Ethernet relies on a point-to-point connection topology. One reason for this approach is to allow network nodes to negotiate their individual mode of communication with the network, i.e., link speed and duplexity. The goals of this paper are twofold. The first goal is to describe the process of link negotiation between nodes. This will include some of the details of how two physical layer devices establish communication. The second goal is to show how networked data acquisition nodes are physically connected within the overall system.

No description available.

published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / Mechanical Engineering / Master / Master of Science in Engineering