Engineering Science and Materials Commons^™

Modeling Reliability Growth In Accelerated Stress Testing, Jason K. Freels

Theses and Dissertations

Qualitative accelerated test methods improve system reliability by identifying and removing initial design flaws. However, schedule and cost constraints often preclude sufficient testing to generate a meaningful reliability estimate from the data obtained in these tests. In this dissertation a modified accelerated life test is proposed to assess the likelihood of attaining a reliability requirement based on tests of early system prototypes. Assuming each prototype contains an unknown number of independent competing failure modes whose respective times to occurrence are governed by a distinct Weibull law, the observed failure data from this qualitative test are shown to follow a poly-Weibull …

Characterization And Processing Evaluation Of Starch/High-Density Polyethylene Materials In Extrusion Blow Molding, Bradley Dale Bacigalupi

Theses and Dissertations

The growing negative impacts of non-biodegradable plastics derived from non-renewable materials have created increasing interest throughout the world for new materials that are both biodegradable and renewable, that can be combined with or replace traditional plastics. Plant-based thermoplastic starch (TPS), a promising alternative material to traditional petroleum based resin, is both biodegradable and renewable and has great potential for use in plastic manufacturing processes. Two major obstacles that prevent more widespread use of TPS include; TPS base material, which is typically manufactured in a flake or powder, is incompatible with standard plastics production equipment that require pelletized resin, the second …

Measuring And Modeling The Mechanical Properties Of Bicycle Tires, Andrew Erwin Dressel

Theses and Dissertations

It has been shown that tire deformation can play an important role in the stability and handling of a bicycle. It is expected that an accurate understanding of tire behavior is necessary for correct understanding of rider behavior and that correct understanding of rider behavior is necessary for optimizing bicycle design. That certainly has been the case for motorcycles.

Several instances of published bicycle tire stiffness data exist, but they seldom agree with each other, do not all measure the same properties, and often are missing key pieces of test configuration data, such as tire size, rim width, inflation pressure, …

Starch Resin Moisture Level Effect On Injection Molding Processability And Molded Part Mechanical Properties With Pure Starch Resin And Polymer Blends, Jordan M. Ellingson

Theses and Dissertations

The current and forecasted global consumption of plastic packaging and products through the 21st century combined with the already reported and growing negative impact of plastics on the environment due to plastics being synthesized from nonrenewable resources that do not biodegrade is of serious concern. However, recent advances in starch technology including the development of thermoplastic starch (TPS) materials —polymers that are both renewable and biodegradable—have brought hope to reducing this impact. The mechanical properties of thermoplastic starch have often been improved by blending with synthetic polymers. One issue that arises with blending is volatilization of the melt from moisture …