Engineering Commons^™

Electrorheology Of Fullerene Suspensions, Maricela Lizcano

Theses and Dissertations - UTB/UTPA

Electrorheological fluids are suspension materials whose rheological behavior changes with an applied voltage. In particular, the material changes from a fluid to a solid behavior with an applied voltage and reverses to its original state when the voltage is removed. This function classifies ER fluids as smart materials. ER fluids may be developed and used as mechanical devices with no mechanical parts such as pumps, actuators, and dampers. Until recently, research was concentrated with micro-particle suspension fluids. This research project investigates the electrorheology of carbon nano-particle suspension.

Design And Manufacturing Of Functionally Graded Materials With Polymer Chain And Nano-Reinforcement Orientation For Compressive Applications, Sanjay Varma Kalidindi

Theses and Dissertations - UTB/UTPA

Functionally Graded Materials for compressive applications were designed and manufactured by tailoring the properties of Pure Polyethylene (PE) and Vapor Grown Carbon Nanofiber (VGCNF) Reinforced PE Composites. Properties of NRPC have been extensively studied. Properties are dependent on parameters such as the reinforcement/matrix interaction; reinforcement volume fraction, orientation, dispersion, and packing, and the final matrix microstructure. However, there is limited literature on their properties under compression loading. Compression strength studies for high density PE reinforced with VGCNF for different fiber volume fraction (0%, 5%, 10% and 15%) were carried out. The role of interface and alignment was studied. Samples were …

Comparison Of Sliding Mode And State-Feedback Control Applied To A Partially Treated Actively Constrained Layer Damped (Acld) Beam, Jose J. Rodriguez

Theses and Dissertations - UTB/UTPA

In this research, a sliding mode control (SMC) was utilized in the control of a partially treated, actively constrained layer damped (ACLD), Timoshenko beam model. The resulting vibration control was compared to the vibration control achieved by a state-feedback linear quadratic regulator (LQR) for several loading conditions. An observer was designed and model order reduction (MOR) was performed to achieve a simplified, efficient, and more controllable finite element system model. As a result of model simplification, modeling errors in the form of unstructured uncertainties were introduced into the system. It was determined that the SMC and LQR achieved similar vibration …

Composite Mechanical Property Enhancement Through The Use Of Y-End Shaped Short Fibers, Jin Tan

Theses and Dissertations - UTB/UTPA

This study uses Finite Element Analysis (FEA) to predict the mechanical property enhancement of the composites reinforced by end-shaped short fibers with different aspect ratios and volume fractions at microscale. Fibers used include conventional straight short fibers (CSSF), dumbbell-end shaped short fibers (DSSF), bone-end shaped short fibers (BSSF) and Y-end shaped short fibers (YSSF) with various lengths and angles. The critical distances between neighboring fiber ends for FEA modeling were theoretically deduced and numerically verified. This study has never been done before and the results fill a gap to this field.

In conclusion, planar-end Y-shaped short fiber reinforced composites showed …

Extension Of Stereolithography Mold Life Using Gas-Assisted Injection Molding, Dilip Bose Ramalingam Nagarajan

Theses and Dissertations - UTB/UTPA

Stereolithography (SL) molds show great promise for injection molding of limited number of parts, greatly reducing the time to product and production cost. However, they present challenges to designers because of their strength, thermal characteristics and shorter lifetimes compared to metal molds. Gas-assisted injection molding (GAIM) has been used to alleviate the problems of distortion and thermal damage. The use of GAIM makes it possible to produce a large number of parts compared to conventional injection molding in epoxy molds with higher quality. In this research solid models of the mold with different part geometry were created using CAD and …