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In Vitro Study To Analyze Reverse Torque Values Of Prosthetic Screws With Multiple Loosening/Tightening Preload Cycles, Amira Alhameed

Master's Theses (2009 -)

Purpose: To determine the number of loosening/tightening preload cycles prosthetic retaining screws can withstand before fracture, and to record the reverse torque values on each of the 10 applications of screw tightening and loosening. Materials and methods: The testing assemblies consisted of 30 temporary cylinder/multiunit abutment/internal connection implants, 10 each from Biohorizons, Zimmer Biomet Dental, and Dentsply Sirona Astra; the specimens were inserted into resin blocks. Temporary cylinders were connected to the abutments with new prosthetic screws and torqued to the appropriate preloads. The first tests of repeated tightening/loosening preload cycles were applied using a Digital ® torque gauge instrument …

A Study Of Rubberfatigue Life And Cure Parameters, Jack Alberts

Master's Theses (2009 -)

is demand for increasing rubber life in parts within medium and heavy duty suspension systems. Rubber plays a major factor in lightening the overall weight of the suspension system; therefore, increasing the hauling capacity of the truck. This thesis focused on optimizing the cure time and cure temperature of the manufacturing process as it relates to the fatigue life of rubber suspension parts. Samples of rubber parts were made using molding techniques with different process parameters, specifically cure time and temperature. These samples then underwent a series of nondestructive tests, to quantify, for example, dynamic stiffness, and then a destructive …

Aging And Muscle Fatigability In The Upper Extremity, Andrew Kuplic

Master's Theses (2009 -)

Aging is accompanied by reductions in strength and contraction velocity, and increased fatigability of limb muscles during high-velocity dynamic contractions. These age-related changes affect functional tasks and are well described for the lower limb, with less known about the upper limb muscles. The aims of the thesis were to compare in young and old men and women: (1) maximal torque and power of the elbow flexor muscles across a range of isokinetic velocities, and (2) the neural (supraspinal) and muscular mechanisms of fatigue induced by high-velocity dynamic contractions of the elbow flexor muscles. 28 young (23.2 ± 2.6 years) men …

Analysis Of Fatigue Crack Propagation In Welded Steels, Roberto Angelo Demarte

Master's Theses (2009 -)

This thesis presents the study of fatigue crack propagation in a low carbon steel (ASTM A36) and two different weld metals (AWS A5.18 and AWS A5.28). Fatigue crack propagation data for each weld wire is of interest because of its use for predicting and analyzing service failures. Fatigue crack growth test specimens were developed and fabricated for the low carbon steel base metal and for each weld wire. Weld specimens were stress relieved prior to fatigue testing. Specimens were tested on a closed-loop servo hydraulic test machine at two different load ratios. Fatigue test data was collected to characterize both …

Abnormal Neuromuscular Fatigue And Motor Performance Of The Knee Extensors Post Stroke, Henry Kuhnen

Master's Theses (2009 -)

Stroke causes paresis in leg muscles, such as the knee extensors, that significantly impairs motor control and function during tasks such as walking. Reduced endurance and increased kinematic asymmetries during walking over time indicate paretic musculature may fatigue more quickly than non-paretic musculature. The primary purpose of this study was to identify abnormalities in neuromuscular fatigue (reduction in force over time) of the paretic knee extensors and associate them with motor performance.

We investigated the effects of repeated six second isometric submaximal (30% of maximum voluntary contraction) knee extensor fatiguing contractions on task failure and motor performance in ten chronic …

Real-Time Health Monitoring System For Mast-Arm Sign Support Structures, Andrew David Smith

Master's Theses (2009 -)

There has been an ongoing study conducted by Marquette University and supported by the Wisconsin Highway Research Program that is seeking to understand the risk of fatigue-induced fracture in the connections of mast-arm sign support structures. This study has been brought on by recent problems encountered with the connections contained in, and the in-service performance of, several cantilevered mast-arm sign support structures. A resulting recommendation of phase one in this effort was to monitoring an in-service cantilevered mast-arm sign support structure.

The health monitoring system developed in this thesis effort includes a grouping of strain gages (full-bridge arrangements) positioned around …