Mechanical Engineering Commons^™

Fabrication Of Complex 3d Micro-Scale Scaffolds And Drug Delivery Devices Using Dynamic Mask Projection Microstereolithography, Jae-Won Choi, In-Baek Park, Ryan B. Wicker, Seok-Hee Lee, Ho-Chan Kim

Dr. Jae-Won Choi

Microstereolithography (μSL) technology can fabricate three-dimensional (3D) tissue engineered scaffolds with controlled biochemical and mechanical micro-architectures. A μSL system for tissue engineering was developed using a Digital Micromirror Device (DMDTM) for dynamic pattern generation and an ultraviolet (UV) lamp filtered at 365 nm for crosslinking the photoreactive polymer solution. The μSL system was designed with x-y resolution of ~2 μm and a vertical (z) resolution of ~1 μm. To demonstrate the use of μSL in tissue engineering, poly(propylene fumarate) (PPF) was synthesized with a molecular weight of ~1200 Da. The viscosity of the PPF was reduced to ~150 cP (at …

Improvement Of Mechanical Properties Of Uv-Curable Resin For High-Aspect Ratio Microstructures Fabricated In Microstereolithography, Su-Do Lee, Jae-Won Choi, In-Baek Park, Chang-Sik Ha, Seok-Hee Lee

Dr. Jae-Won Choi

Recently, microstructures fabricated using microstereolithography technology have been used in the biological, medical and mechanical fields. Microstereolithography can fabricate real 3D microstructures with fine features, although there is presently a limited number of materials available for use in the process. Deformation of the fine features on a fabricated microstructure remains a critical issue for successful part fabrication, and part deformation can occur during rinsing or during fabrication as a result of fluid flow forces that occur during movement of mechanical parts of the system. Deformation can result in failure to fabricate a particular feature by breaking the feature completely, spatial …

Development Of A Multi-Material Stereolithography System, Ho-Chan Kim, Jae-Won Choi, Ryan B. Wicker

Dr. Jae-Won Choi

Researchers continue to explore possibilities for expanding additive manufacturing (AM) technologies into direct product manufacturing. One limitation is in the materials available for use in AM that can meet the needs of end-use applications. Stereolithography (SL) is an AM technology well known for its precision and high quality surface finish capabilities. SL builds parts by selectively crosslinking or solidifying photo-curable liquid resins, and the resin industry has been continuously developing new resins with improved performance characteristics. This paper introduces a unique SL machine that can fabricate parts out of multiple SL materials. The technology is based on using multiple vats …

Fabrication Of Microstructure Array Using The Projection Microstereolithography System, Jae-Won Choi, Young-Myoung Ha, Seok-Hee Lee

Dr. Jae-Won Choi

Microstereolithography technology is similar to the conventional stereolithography process and enables to fabricate a complex 3D microstructure. This is divided into scanning and projection type according to aiming at precision and fabrication speed. The scanning MSL fabricates each layer using position control of laser spot on the resin surface, whereas the projection MSL fabricates one layer with one exposure using a mask. In the projection MSL, DMD used to generate dynamic pattern consists of micromirrors which have per side. The fabrication range and resolution are determined by the field of view of the DMD and the magnification of the projection …

Pneumatic Tire, Alan Neville Gent, Joseph D. Walter

Dr. Joseph D. Walter

For many years, tire engineers relied on the monograph, 'Mechanics of Pneumatic Tires', for detailed information about the principles of tire design and use. Published originally by the National Bureau of Standards, U.S. Department of Commerce, in 1971, and a later (1981) edition by the National Highway Traffic Safety Administration (NHTSA), U.S. Department of Transportation, it has long been out of print. No textbook or monograph of comparable range and depth has appeared since. While many chapters of the two editions contain authoritative reviews that are still relevant today, they were prepared in an era when bias ply and belted-bias …

Isolation And Dissociation Of Immune Complexes From Pleural Effusions Of Lymphoma Patients, Geeta V. Patel, Mangesh N. Satam, Gopal Nadkarni

Dr. Gopal Nadkarni

Immune complexes (IC) isolated from pleural effusions of lymphomas with favorable and unfavorable prognoses were of IgG type. These IC were further dissociated by ion exchange chromatography using 8 M urea. The antibody was found to be a high molecular weight protein (1.5 x l0 s daltons) and reacted with antihuman IgG immunologically while a second peak obtained on ion exchange chromatography may be an antigen moiety with a molecular weight of 3.2 × 10 4 daltons as it reacted immunologically with the antibody. Strong cytoplasmic fluorescence was observed with various cell suspensions of lymphomas when reacted with the antibody …

Quantification Of The Effect Of Tool Geometric Features On Aspects Of Friction Stir Welding, Md. Reza-E-Rabby

Theses and Dissertations

In the friction stir welding (FSW) process, tool stirring and synchronized movement of the weld materials along a pre-existing seam line causes thermal gradients and severe plastic deformation resulting in the bonding of the adjacent materials. For a given set of welding parameters, tool pin geometries (dimensions, shape) and vertical/helical features that dictate the material motion also have significant effects on process response variables during FSW. Among the primary process controlling parameters in FSW, tool pin geometry and feature vary multifariously in terms of shape, dimensions, feature insertion technique depending on the weld material and application of joint. The current …

Design Of Experiments Analysis Of Non-Standard Inputs For The Optimization Of Friction Stir Welding, Ryan Widejko

Theses and Dissertations

The purpose of this study was to use non-standard Design of Experiments (DoE) inputs in Friction Stir Welding (FSW) to deduce relationships between various weld input and response variables. Typically, inputs for FSW DoE are tool rotational speed, welding speed and forge force. In this study, three different input factors were investigated: travel speed, thermal boundary conditions (TBC), and advance per revolution (APR). The experimental design included a full factorial with each factor at two levels plus two centerpoint runs. Response variables included weld temperature, microstructure, hardness, power, weld energy, and in plane forces.

An investigation of the effect of …