Title of Document: THERMO-MECHANICAL DESIGN STUDY OF FIBER OPTIC PRESSURE SENSOR DIAPHRAGMS. Yasir Majeed, Master of Science, Mechanical Engineering, 2009 Directed By: Professor Abhijit Dasgupta, Department of Mechanical Engineering This thesis parametrically explores the nonlinear design sensitivity of a fiber optic pressure sensor (FOPS), based on selected thermo-mechanical failure mechanisms...

In this paper we report on the mechanism of delamination in light-emitting diode (LED) packages and its effects on thermal characteristics of LEDs. The LED samples were subjected to moisture preconditioning treatments followed by heat block testing. Transient thermal measurements were performed for the investigation of the thermal behavior of the delaminated LEDs. Increase of thermal resistance...

A set of constitutive equations for large rate-dependent elastic–plastic-damage materials at elevated temperatures is presented to be able to analyze adiabatic high strain rate deformation processes for a wide range of stress triaxialities. The model is based on the concepts of continuum damage mechanics. Since the material macroscopic thermo-mechanical response under large strain and high stra...

Rubber-like materials can undergo very large strains in a quasi-reversible way. This remarkable behavior is often called hyper (or entropic) elasticity. However, the presence of mechanical loops during a load-unload cycle is not consistent with a purely elastic behavior modeling. Using Digital Image Correlation and Infra-Red Thermography, the present study aims at observing and quantifying diss...

In this paper, a novel temperature-dependent multi-scale method is developed to investigate the role of temperature on surface effects in the analysis of nano-scale materials. In order to evaluate the temperature effect in the micro-scale (atomic) level, the temperature related Cauchy-Born hypothesis is implemented by employing the Helmholtz free energy, as the energy density of equivalent cont...

Based on the thermo elasticity, using finite element method to analyze the stress of femur-prosthesis system when the hip joint has been replaced, a reference for the selection of prosthesis material is presented after discussing the thermo physical property of material which has an effect on the stress of femur-prosthesis system. We assume that prosthesis, bone cement and femur are linear elas...

Three-dimensional nonlinear thermal and thermo-mechanical numerical simulations are conducted for the friction stir welding (FSW) of 304L stainless steel. The finite element analysis code—WELDSIM, developed by the authors specifically for welding simulation, was used. Two welding cases with tool rotational speeds of 300 and 500 rpm are analyzed. The objective is to study the variation of transi...

Nanowires (NWs) exhibit thermo-mechanical properties that are distinct from their bulk properties, and their understanding is critical for the reliability, manufacturability, and optimization of a wide range of devices consisting of NWs. Here, molecular-dynamics simulation reveals a rich size-temperature “phase diagram” for the mechanical response of a zinc-oxide NW under tension. For smaller d...

in this paper, a thermoelasticity solution for steady state response of thick cylinders which are subjected to pressure and external heat flux in inner surface is presented. displacement field obeys the kinematics of the first order shear deformation theory (fsdt). it is assumed that the temperature varies both along the length and the thickness. the variation of the temperature occurs linearly...

Based on the coupled thermo-mechanical model, a constitutive model for bulk metallic glasses (BMGs), which is generalized to the multi-axial stress state and considers the effects of free volume, heat and hydrostatic stress, has been modified in the present paper. Besides, a failure criterion of critical free volume concentration is introduced based on the coalescence mechanism of free volume. ...