Engineering Commons^™

Reliability Of Lead-Free Solder Joints Under Combined Shear And Compressive Loads, Ian Bernander, Travis Dale, Yuvraj Singh, Ganesh Subbarayan

The Summer Undergraduate Research Fellowship (SURF) Symposium

In electronic assemblies, solder joints are used to create electrical connections, remove heat, and mechanically support the components. When an electronic device is powered on, the solder joints and the board they are attached to heat up, expanding at different rates. Due to the difference in expansion, shear stress is imposed on the solder joints. As the device is powered on and off, this shear stress can eventually fracture the solder joint, causing the device to fail. Therefore, to increase the lifespan of electronics, it is important to investigate the mechanical properties of solder alloys. The present study investigates how …

Creep Of Hi-Nicalon™ S Ceramic Fiber Tows At 1100°C In Air And In Silicic Acid-Saturated Steam, Logan M. Gumucio

Theses and Dissertations

Innovations in SiC based ceramic matrix composites (CMCs) have yielded exceptional high-temperature properties and performance in aggressive oxidizing environments. These material characteristics provide potential avenues for future advancements in many applications where current metallic alloys perform near their operating temperature limits in a harsh environment. As steam (typically present in these environments) enters through cracks in the matrix of a SiC/SiC composite, it leaches Si and becomes saturated with silicic acid, Si(OH)₄, prior to attacking the reinforcing SiC fibers. Therefore, it is paramount that a thorough understanding of the performance and durability of SiC fibers be obtained under …

Creep Of Hi-Nicalon™ S Ceramic Fiber Tows At 1000°C In Air And In Silicic Acid-Saturated Steam, Brian G. Kroeger

Theses and Dissertations

Advanced SiC/SiC ceramic matrix composites (CMCs) are being considered for a variety of applications. Of interest is their ability to withstand exposure to high temperature in an aggressive oxidizing environment. The presence of steam creates such an environment. As steam traverses across a SiC/SiC composite and through cracks in the SiC matrix, it becomes saturated with silicic acid, Si(OH)₄. It is essential to understand the long-term impacts and durability of SiC/SiC CMCs that have been exposed to such a demanding environment. The present research investigated creep of Hi-Nicalon™ S SiC fibers at 1000°C in air and in silicic …

Design And Testing Of A Linear Compliant Mechanism With Adjustable Force Output, William Niemeier

USF Tampa Graduate Theses and Dissertations

This thesis presents a novel compliant mechanism with adjustable force output. The force comes from the bending of a rectangular cross section beam within the mechanism. By rotating this beam with a stepper motor, the force output of the mechanism changes. A model was made to simulate this mechanism, and a prototype was made based off of this data. A test apparatus was constructed around this mechanism, and a series of tests were performed. These tests adjusted parameters such as beam rotation speed and weight in order to characterize the system. Adjustments were made based on this information and the …

High Temperature Compression Creep Of U3si2, Emil Angelo Cahanap Mercado

Theses and Dissertations

As a result of the Fukushima Daiichi Nuclear Disaster in 2011, a push for increasing the safety of nuclear power plants was made through research grants funded through the United States Department of Energy via the Accident Tolerant Fuels (ATF) campaign. One of the focuses of the campaign is improving the accident tolerance of nuclear fuel during a loss of coolant accident.

A promising set of being researched from the ATF is Silicon Carbide (SiC) composite cladding and Uranium Silicide (U3Si2) fuel pellets. Under high temperatures, stresses, and times the creep deformation can play an important factor in pellet to …

Constitutive Modeling Of Creep In Leaded And Lead-Free Solder Alloys Using Constant Strain Rate Tensile Testing, Eric Thomas Stang

Browse all Theses and Dissertations

Environmental and safety concerns have necessitated a phase-out of lead-based alloys, which are often used in electronics solder applications. In order to properly assess suitable replacement materials, it is necessary to understand the deformation mechanisms relevant to the application. In the case of electronics solder, creep is an important mechanism that must be considered in the design of reliable devices and systems. In this study, Power-Law and Garofalo constitutive creep models were derived for two medium temperature solder alloys. The first alloy is known by the commercial name Indalloy 236 and is a quaternary alloy of lead, antimony, tin, and …