Aerospace Engineering Commons^™

Solder Ball Reliability Assessment Of Wafer Level Chip Scale Package (Wlcsp) Through Power Cycling, Bhavna Conjeevaram

Mechanical and Aerospace Engineering Theses - Archive

Failure analysis and its effects are major reliability concerns in electronic packaging. More accurate fatigue life prediction can be obtained after the consideration of all affecting loads on the electronic devices. When an electronic device is turned OFF and then turned ON multiple times, it creates a loading condition called Power Cycling. The die is the main heat source causing non-uniform temperature distribution. The solder ball reliability assessment of wafer level chip scale package (WLCSP) is done through computational methods such as Finite element analysis. WLCSPs use wafer level package technology which is an extension of the Wafer Fab process, …

Computational Study Of Impact Of Thermal Shadowing In Non-Directed Flow For Air And Oil Cooled Servers. Form Factor Study And Customization Of Heat Sink For Data Center Application, Chinmay Hemantkumar Bhatt

Mechanical and Aerospace Engineering Theses - Archive

In today’s networking world, the usage of Servers and Data centers has been increasing significantly with a corresponding increase in power. The data center energy efficiency largely depends on thermal management of servers. Currently, air cooling is the most widely used thermal management technology in data centers. However, air cooling is starting to reach its limits due to high powered microprocessors and packaging. To overcome these limitations of air cooling in data centers, liquid cooling methods are starting to gain more traction. Thermal shadowing is the effect in which temperature of a cooling medium increases by carrying heat from one …

Static And Dynamic Fea Analysis Of A Composite Leaf Spring, Himanshu Arun Raut

Mechanical and Aerospace Engineering Theses - Archive

Composite materials are widely used in aeronautical, marine and automotive industries, because of their excellent mechanical properties, low density and ease of manufacture. Due to this increasing trend to utilize composite materials, it has become necessary to investigate the pros and cons of composites. This research investigated the static and dynamic behaviors for a composite leaf spring that are used in Chevrolet Corvette Grand and light tractor-trailers. The objective of this study was to find the cause of de-lamination/ failure of the unidirectional composite layers in varying cross sections of the leaf spring. Finite element method is used to calculate …

Trajectory Optimization Using Indirect Methods And Parametric Scramjet Cycle Analysis, Joseph Williams

Open Access Theses

This study investigates the solution of time sensitive regional strike trajectories for hypersonic missiles. This minimum time trajectory is suspected to be best performed by scramjet powered hypersonic missiles which creates strong coupled interaction between the flight dynamics and the performance of the engine. Comprehensive engine models are necessary to gain better insight into scramjet propulsion. Separately, robust and comprehensive trajectory analysis provides references for vehicles to fly along. However, additional observation and understanding is obtained by integrating the propulsion model inside the trajectory framework. Going beyond curve fitted thrusting models, an integrated scramjet cycle analysis offers rapid trade studies …

Computational Fluid Dynamics Is Key To Better Flying Aircraft, Nihad E. Daidzic

Aviation Department Publications

No abstract provided.

Numerical Investigation Of Vortex Generators And Jet In Cross-Flow Enhancements, Aditya Raman

Mechanical and Aerospace Engineering Dissertations - Archive

Vortex generators have extensively been used over the past few decades for heat transfer applications. Their passive form of enhancement coupled with the ease of their implementation is the primary reason for their growing popularity. The streamwise counter rotating vortex pair (CVP) that is formed downstream of these vortex generators act as a source of energy that can set up stirring scales to enhance heat transfer and improve mixing. The CVP can be used to energize the boundary layer in the case of wall bounded flows, and as a consequence vortex generators have also been used to delay flow separation. …

Computational Design And Flow Analysis Of Smart Flow Control Device For Dynamic Cold Plate Used In Computer Server Cooling, Sruthi Errukula

Mechanical and Aerospace Engineering Theses - Archive

One of the areas which Electronics cooling research is focusing on is high heat fluxes and non-uniform power distribution. Cooling is always required for maximum junction temperature and as such it is important to mitigate hot spots. These hot spots result in large temperature differences across the surface of high-end devices such as multi-core chip scale packages. One possible solution for non-uniform power distribution across the chip can be use of dynamic cold plate cooling along with smart flow control device and thus this project aims at developing and testing of dynamic cold plate integrated with use of smart flow …

Fiber Bragg Grating (Fbg) Sensors For The Simultaneous Measurements Of Strain And Temperature, Abhay Kumar Singh

Mechanical and Aerospace Engineering Theses - Archive

This research presents a single fiber Bragg grating (FBG) sensor that is capable of measuring the axial load and temperature simultaneously. The FBG sensor is coated with a block of recrystallized Lophine, which introduces the bandwidth modulation of the FBG reflectance spectrum. Thermal-mechanical testing of the Lophine-coated FBG sensor under different load and temperature combinations was carried out. It was discovered that the FBG bandwidth is linearly proportional to the applied load and temperature. By fitting the measured FBG bandwidths and central Bragg wavelengths as linear functions of the axial load and temperature, we demonstrated that the axial load and …

Effect Of Viscoelastic Modeling Of Pcb On The Board Level Reliability Of Wafer Chip Scale Package (Wcsp) In Comparison To Orthotropic Linear Elastic Modeling, Avinash Anaskure

Mechanical and Aerospace Engineering Theses - Archive

The assessment of board level solder joint reliability during thermal cycling is very important for electronic packages. During thermal cycling, the mismatch in Coefficient of Thermal Expansion (CTE) between the materials used in the package induces stress on the solder interconnects and result in deformation stresses. Finite element tools are widely used for rapid design optimization and also for understanding board level reliability issues. Lumped board properties approach, explicit geometry approach, and ECAD approach are the three widely used approaches for creating models for PCBs. In the lumped board properties approach, orthotropic elastic material properties are assigned to PCBs. However, …

Effect Of Manufacturing-Induced Defects And Orientation On The Failure And Fracture Mechanism Of 3d Printed Structures, Amit Khatri

Mechanical and Aerospace Engineering Theses - Archive

Additive manufacturing is a rapidly growing cutting edge technology. Number of experimental studies have shown that strength of product manufactured by additive Fused Deposition Method (FDM) is influenced by different processing parameters involved during manufacturing. This thesis work presents experimental and theoretical investigation of mechanical behavior of ABS material fabricated with variation in some of process parameters such as Axis Orientations, Raster Orientation, Infill Percentage, Layer Height and Number of Shells. Different experiments were designed to understand the basics of 3D printing manufacturing and to characterize the mechanical behavior of 3D printed structures. This study helps to understand, how different …

Design Of Flow Control Device For Dynamic Cold Plate And Optimization Of Servers To Decrease Junction Temperature Of Heat Sinks, Kunal Atulkumar Shah

Mechanical and Aerospace Engineering Theses - Archive

Electronics cooling research is facing the challenges of high heat flux removal and increased pumping power. Not much attention has been focused related to server and module level cooling. The continued increase in heat fluxes at the chip level due to new and robust technology nodes following Moore’s law is starting to push the limits of air cooling and especially for high end servers. An alternative to air cooling is liquid (water and oil immersed) cooling. The optimized dynamic cold plates that use water as the cooling fluid have shown over 28 % and 52% of reduction in pumping power …

Accumulator Volume Sensor Final Project Report, Chris Naughton, Kinwei Yu, Michael George

Mechanical Engineering

Accumulator Volume Sensing Team has developed two sensor designs aimed at detecting the position of the piston within a 4024 accumulator. The two designs include the use of a Renishaw LMA10 magnetic encoder and a SpectraSymbol HotPot linear potentiometer. The magnetic encoder solution drastically increases the accuracy of sensing the piston position compared to the current solutions of both a string-pot and linear variable differential transformer while costing slightly less. The linear potentiometer seeks to provide a solution that drastically decreases the cost compared to the present sensing methods. Both designs call for a modification to one half of the …

Numerical Investigation Of Crossflow Instability On The Hifire-5, Matthew T. Lakebrink

Open Access Dissertations

Stability analysis was performed with the Langley Stability and Transition Analysis Code (LASTRAC) on a 38.1% scale model of the HIFiRE-5 elliptic-cone forebody to study crossflow-induced transition in hypersonic boundary layers. A resolution study consisting of three grids (30e6, 45e6, and 91e6 points) indicated that the fine grid was sufficiently resolved. Results were largely insensitive to grid resolution over the acreage and near the attachment line. The percent variation in second-mode properties along the semi-minor axis was less than 1% between the medium and fine grids. The variation in crossflow-wave properties was less than 0.04% between the medium and fine …

Integration And Qualification Of The P-Pods On The Vega Maiden Flight, Ryan Nugent

Master's Theses

On February 13, 2012, California Polytechnic State University, San Luis Obispo flew three Poly-Picosatellite Orbital Deployers (P-PODs), carrying seven European University CubeSats sponsored by the European Space Agency (ESA), on the Vega Maiden Flight. This was the first time CubeSats shared a ride to space with other payloads on an ESA-owned launch opportunity. In order to meet launch requirements, it must be proven through proper documentation that the P-POD would operate properly and not interfere with the launch vehicle or other payloads on the mission. This thesis outlines the program flow, required documentation, and issues encountered during the launch campaign …

A Genetic Algorithm Incorporating Design Choice For The Preliminary Design Of Unmanned Aerial Vehicles, Kenneth Michael Mull

Masters Theses

Unmanned Aerial Vehicles (UAVs) are currently at the forefront of aerospace technologies. The design of these aircraft is complex and often performance characteristics are coupled to multiple design attributes. At the early design phase both discrete and continuous design choices are present limiting the feasibility of traditional derivative based optimization techniques. In place of these methods, the design space can be explored using a genetic algorithm that mimics the process of natural selection, providing a capable and reliable base airframe constructed from the required performance metrics. By incorporating a genetic multidisciplinary optimization algorithm early in the conceptual design phase, aircraft …

Modeling, Optimizing And Testing Thermoelectric Generators For Liquid-To-Liquid Low Grade Waste Heat Recovery, Ali Eyddan Hamil

Masters Theses

The use of thermoelectric generators (TEGs) for producing electricity from low grade waste heat is thought to be a great solution in the future to reduce the power generation cost because of their advantages of reliability and environmental friendliness. Therefore, the current project aims to study thermoelectric generators for low grade waste heat recovery. In this work, a single unit cell of liquid to liquid thermoelectric generator attached with heat exchangers (heat sinks) is modeled using an internal flow. Its optimum design is obtained based on heat sink optimization and the optimal design method. An analytical model of four unit …

Analytical Study Of Miniature Thermoelectric Device, Mohammed Dhannoon

Masters Theses

Miniature thermoelectric devices (TE) have been regarded as hopeful devices to attain efficient cooling in microprocessors and other small-scale devices. To recognize the performances of miniature thermoelectric coolers, a thermoelectric cooling module is theoretically analyzed. Particular attention is paid to the impact of the thermoelectric element length effect and the substrate material type influence on the cooling performance. The electrical contact resistance and thermal contact are taken into account.

Furthermore, miniature thermoelectric is compared with large thermoelectric, and effective material properties of miniature thermoelectric are studied. The obtained results also demonstrate power density (cooling/heating power per unit area of the …

Effects Of The Cooling Rate On The Shear Behavior Of Continuous Glass Fiber/Impact Polypropylene Composites (Gf-Ipp), H. Wafai, G. Lubineau, A. Yudhanto, M. Mulle, W. Schijve, N. Verghese

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Fiber-reinforced composites with improved dissipation of energy during impact loading have recently been developed based on a polypropylene copolymer commonly called impact polypropylene (IPP). Composites made of IPP reinforced with glass fibers (GF) are particularly attractive to the automotive industry due to their low cost and good impact resistance. In such composites, the cooling rate varies depending on processing techniques and manufacturing choices. Here, we study the effects of the cooling rate of GF-IPP composites on shear behavior, which is critical in impact applications, using [±45]s monotonic and cyclic (load/unload) tensile specimens. The specimens were manufactured under a wide range …

A Robotic Device To Assist With In-Vivo Measurement Of Human Pelvic Organ Tissue Properties, Shashank S. Kumat

Mechanical and Aerospace Engineering Theses - Archive

Measurement of the biomechanical properties of human pelvic organ tissue without undergoing minimally invasive surgery is desired for diagnostics purposes and take precautionary actions if needed. The biomechanical properties of the bladder change with age and due to diseases. Thus, identification of the viscoelastic properties of the tissue could help in detecting early stages of the disease in the bladder. A literature survey revealed that no device exists that could be used to characterize the biomechanical properties of the human bladder in-vivo. This research contributes towards the development of a diagnostic system that could be used in a medical setting …

The Influence Of Functional Weights On The Performance Of Least Squares Finite Element Formulation On Hybrid Meshes, Anirudh Rajagopal

Mechanical and Aerospace Engineering Theses - Archive

The Least-Squares Finite Element Method (LSFEM) is a numerical method for solving partial differential equations (PDE) approximately by minimizing the L-2 norm of the PDE residuals. Unlike the more common Galerkin approach, this method does not employ integration by parts to reduce the continuity requirements of the basis functions. Instead, the PDE is cast as a first-order system of differential equations, which allows for the solution of primary and secondary variables with the same order of accuracy. In addition, this approach always leads to a direct minimization problem and therefore not subject to the restrictive inf-sup condition and does not …