Mechanical Engineering Commons^™

Vibration Fatigue Of Leaded Solder Joint Interconnects For Pcb Electronics, John Crowder

All Theses

With the increasing prevalence of electronic equipment worldwide, there is also a decrease in the size of the components on their printed circuit boards (PCBs), leading to an increase in the density of these components. A significant amount of failure in electronic equipment is vibration fatigue of solder joints and their attachments. However, the complexity of these PCBs and their components has made finite element modeling (FEM) more complex, adding considerable time to create and analyze a model.

This paper aims to provide a literature review for the vibration fatigue of leaded solder components, create a test setup, and validate …

Fatigue And Fracture Of Electron Beam Melting Ti-6al-4v, William A. Grell

Electronic Theses and Dissertations

For applications in the aerospace field, selection of materials for a given design requires an understanding of critical properties, like fatigue and fracture, in addition to static mechanical and physical properties. With the ongoing advancements in metallic additive manufacturing techniques and the interest in applying the process to aerospace applications, there is a clear need to fully characterize properties. Arguably, the most attractive alloy for applications in aerospace is the Ti-6Al-4V alloy. The current dissertation examines the mechanical properties of the alloy, made by the Electron Beam Melting (EBM) Powder Bed Fusion (PBF) method. As illustrated in this work, the …

Investigation Of Fatigue Response With Analytical And Machine Learning Models And Hygroscopic Analysis Of Asymmetric Bistable Cfrp Composites, Shoab Ahmed Chowdhury

All Dissertations

Asymmetric bistable carbon fibre reinforced plastic (CFRP) composites enable a broad range of applications as they can sustain multiple stable configurations and have small snap-through load requirements. These unique features, coupled with their light strength-to-weight and stiffness-to-weight ratios, have made them preferred options for multifunctional systems. This study investigates the fatigue and hygroscopic response of 2-ply, [0/90] bistable CFRP laminates and proposes predictive modeling approaches for improved performance.

While previous studies widely researched and documented the fatigue of general composites in axial loading, fatigue analysis of asymmetric bistable composites in the out-of-plane snap-through direction is inadequate. This study performs fatigue …

Timing Deterministic Structural Model Updating Considering Impact And Fatigue Damage, Jason Michael Smith Jr.

Theses and Dissertations

Naval ship structures such as support trusses, hull sections, driving machinery, and load-bearing beams are subjected to various damage states that develop on short-term (i.e. impact) and long-term (i.e. fatigue) timescales. Naval structures fitted with a structural health monitoring system with damage detection abilities will enable appropriate real-time adjustments to the ships’ posture and control policies and thus have increased survivability and lethality. A digital twin can provide real-time condition assessment of naval structures when conjoined with a decision-making framework will increase naval ship survivability through informed response management. A fundamental challenge for the development of digital twins is reliable …

Comparing The Performance Of Different Machine Learning Models In The Evaluation Of Solder Joint Fatigue Life Under Thermal Cycling, Jason Scott Ross

Dissertations and Theses

Predicting the reliability of board-level solder joints is a challenging process for the designer because the fatigue life of solder is influenced by a large variety of design parameters and many nonlinear, coupled phenomena. Machine learning has shown promise as a way of predicting the fatigue life of board-level solder joints. In the present work, the performance of various machine learning models to predict the fatigue life of board-level solder joints is discussed. Experimental data from many different solder joint thermal fatigue tests are used to train the different machine learning models. A web-based database for storing, sharing, and uploading …

Analysis Of The Self-Heating Effect On Unfilled Poly(Methyl Methacrylate) Due To Cyclic Behavior, Muhammed R. Kose

All Theses

Poly(methyl methacrylate, (PMMA) has been implemented as part of the supporting structure in complete hip and knee replacements since the 1950s. Known as bone cement while in the body, PMMA is known to undergo compressive and tensile stresses that wear down the bio-compatible barrier and cause pieces to come loose inside the human body. These pieces are then attacked by the body’s own nervous system, leading to inflammation, and eventually necessitating replacement. It has been documented that under cyclic loading PMMA can reach temperatures that start to degrade its tensile capabilities. In this study the potential cause of self-heating was …

On The Influence Of Afp-Induced Defects On Mechanical Behavior Of Composite Laminates Under Fatigue Loading, Pierre Chevalier

Theses and Dissertations

The objective of the work presented in this thesis is to propose and validate a numerical solution to quantify the influence of Automated Fiber Placement (AFP) induced defects on the mechanical behavior of conventional composite laminates in fatigue. The work presented here will be divided in six sections. At first, a description of the Automated Fiber Placement process and its associated defects is proposed. In association, two tools developed for a rapid analysis and a progressive damage analysis respectively are discussed and used as an introduction to the work conducted in this thesis. In the second section, an extensive literature …

Exploration Of Warm-Up Protocols On Muscular Fatigue, Sahil Kapadia

Honors Undergraduate Theses

Muscular dystrophy is a genetically linked myopathy with no cure available. The lack of a cure makes early detection and treatment of muscular dystrophy imperative. When reviewing protocols examining muscular fatigue at submaximal isometric contractions, proper warm-up appeared to be absent and could have caused skewed results and conclusions. This study examines the effects of implementing a warm-up protocol before fatiguing trials. In this study, 10 adult subjects conducted fatiguing protocols with the right rectus at submaximal isometric contractions. The warm-up period included a light walk along with contractions at 20% and 33% of maximal voluntary isometric contraction (MVIC) levels. …

Vibration Bending Fatigue Analysis Of Additively Repaired Ti-6al-4v Airfoil Blades, Lucas Jordan Smith

Browse all Theses and Dissertations

Repairing airfoil blades is necessary to extend the life of turbine engines. Directed energy deposition (DED) additive manufacturing (AM) provides the ability to add material at a specific location on an existing component. In this work, AM repairs on Ti-6Al-4V airfoil blades were analyzed to determine what effect the repair will have on the blade performance in high cycle vibration fatigue testing. Targeted sections were cut out of airfoil blades near high stress locations and repaired using DED. To understand the defects that arose with this type of repair, computed tomography imaging was used to quantify the defects from the …

Assessing Mechanical Performance Of Dissimilar Steel Systems Made Via Wire-Arc Additive Manufacturing, Obed Daniel Acevedo

Masters Theses

Hot stamping is part of a specific type of metalworking procedure widely used in the automotive industry. This research seeks to help make hot stamp tooling component production more cost-effective by using large-scale additive manufacturing. Additive manufacturing can produce dissimilar steel components that can be more cost-effective and time-efficient and allow for complex geometries to be made. A dissimilar steel system consisting of 410 martensitic stainless steel and AWS ER70S-6 mild steel is proposed to make hot stamps, making them more cost-efficient. However, the material interface's mechanical behavior in 410SS-mild steel additively manufactured material systems is not well understood. This …

Significance Of The Neck In Concussive Head Impacts – A Computational Approach, Sakib Ul Islam

Electronic Thesis and Dissertation Repository

With the rising concern of concussions in contact sports, it is believed that cervical muscles could play a vital role in attenuating force to the head. However, the biomechanical effect of cervical muscles on head and brain response is not clearly understood. This study adopted a finite element head and neck model to replicate football impacts under various loading conditions to study the effect of neck muscles on head kinematics. Our results indicate that neck muscles have the highest amount of internal energy absorption in early impact, particularly at the time when peak head kinematics develop. Both deep and superficial …

Effect Of Obesity On Knee Joint During Walking And Squatting, Simon Vasquez Iii

Theses and Dissertations

This paper analyzes the effect of obesity on the knee joints during squats. This was performed on 2 different subjects by having each squat 30 times at their decided comfortable depth to display some fatigue and effects on the knee joints. Using the VICON NEXUS and AMTI force plates equipment at The University of Texas at Rio Grande Valley Biomechanics Lab, the center of pressure, knee flexion angles, velocity, and ground reaction forces were calculated. The subjects performed the exercises with and without additional weight using a body vest and kettlebell. The ground reaction forces showed a significant increase in …

Electromyographic And Mechanomyogrpahic Signal Changes With Fatigue In Adults, Rehana Koilpillai

Honors Undergraduate Theses

Surface electromyography (sEMG) and mechanomyography (MMG) are well-studied signals that can reveal information about the physiological behavior of muscles during contraction. The purpose of this study was to quantify, characterize, and analyze the electrical and mechanical muscle responses to submaximal, isometric contractions in the rectus femoris in adults. Previous studies have investigated the use of EMG to monitor muscle fatigue. However, more information appears to be needed about the use of MMG to measure muscle fatigue during submaximal isometric contraction in the rectus femoris. In this study, the utility of MMG as a measure of muscle fatigue or muscle state …

Constitutive Modeling Of Force-Controlled Fatigue Testing In Human Meniscus Tissue, Bradley Scott Henderson

Boise State University Theses and Dissertations

The meniscus is a wedge-shaped fibrocartilaginous tissue located between the femur and tibia that helps stabilize the knee and protect the underlying cartilage. There are 2.5 million reported knee injuries each year, making it the most injured joint in the human body. Nearly twenty percent of these injuries are due to a torn meniscus, leading to over half a million meniscus surgeries performed in the United States annually. Therefore, it is critical to understand the failure modes of meniscus tissue to prevent these debilitating injuries. A failure mode that accounts for one-third of all meniscus injuries is repeated exposure to …

Selective Laser Melting 17-4 Ph Stainless Steel And The Effect Of Varied Thermal Treatments On Fatigue Behavior., Sean Daniel Dobson

Electronic Theses and Dissertations

Fatigue failure is the leading source of loss in industry. In order for new means of manufacturing to move towards mainstream use a complete understanding of material and mechanical behavior must be gained. This endeavor seeks to aide in that task by observing the fatigue behavior of selective laser melting (SLM) additive manufacturing (AM) specimens and the effect of differing thermal treatment conditions for an optimized AM process. Stainless steel 17-4 PH specimens were fabricated using SLM AM and thermally treated to three conditions: as-built, solutionized and hardened, and direct hardened. These specimens were characterized for material (powder quality, density, …

Implementation Of A 2d Bond Based Peridynamic Fatigue Model In Fem, Kyle Mansfield

Graduate Research Theses & Dissertations

A relatively new fracture theory known as peridynamics has been developed which uses a nonlocal theory to describe crack growth, resolving many of the issues associated to the classical continuum theory. Internal material interactions are described via a family of ‘bonds’, capable of exerting force over a macro-scale region of influence known as the horizon. Bond damage accumulates naturally due to repeated cyclic or critical loading and damage precipitates as a growing crack as bonds reach a critical damage and are severed. In the present work a modified compact tension specimen subjected to cyclic loading is modeled with the 2D …

Thermal / Structural Analysis Of The Hb 650 Thermal Shield, Gerald J. Smith

Graduate Research Theses & Dissertations

Fermilab’s PIP-II project’s superconducting linear accelerator (Linac) will drive the next generation of particle accelerators through a revolution in beam intensity. Key to beam intensification are the high efficiencies of niobium-tin superconducting radiofrequency (SRF) cavities operating at cryogenic temperatures near 5 Kelvin. A multifaceted approach is employed to achieve and maintain the extreme temperature. Vacuum provides the first barrier to thermal convection. Physical thermal intercept zones further isolate the exterior shell vacuum vessel at 300 Kelvin from the supercooled beamline. The first thermal intercept lies just inside the exterior vacuum vessel forming the 40 Kelvin zone. This 40K thermal shield …

Evaluation Of Control Strategies For Overhead Work Using Electromyography Of Rotator Cuff Muscles, Hossein Motabar

Graduate Theses, Dissertations, and Problem Reports

Work-related musculoskeletal disorders (MSDs) of shoulder have a significant impact on overall health and economics in the industrialized nations. Rotator cuff is the most frequently injured region in the shoulder complex. Overhead work is considered as one of the most predominant causes of rotator cuff injuries. The workers in construction, automotive, and aerospace industries are routinely exposed to overhead exertions. Elimination of overhead work is nearly impossible due to various task and technology constraints. Therefore, appropriate intervention strategies based on the engineering and administrative controls opt to be used to prevent the hazardous impact of overhead exertions. The objective of …

Comparision Of Fillet-Welded Base Plate Fatigue Design For Highway Support Structures With Laboratory Research Tests, William Shea

Williams Honors College, Honors Research Projects

There are many types of vertical structures along highways that serve unique purposes. These structures include traffic signs for directing, warning, or regulating traffic, luminaires for distributing and directing light, traffic signals supporting equipment such as traffic lights, and combination structures including any combination of the aforementioned structures. Highway support structures are typically fabricated from steel or aluminum and are designed to the guidelines and specifications of the AASHTO Standard Specifications for Structural Supports for Highway Signs, Luminaires, and Traffic Signals. The structures are connected to a foundation by anchor bolts through a welded base plate. Often a cause …

Defect Modeling And Vibration-Based Bending Fatigue Of Additively Manufactured Inconel 718, Wesley Earl Eldt

Browse all Theses and Dissertations

Additive manufacturing (AM) is convenient for building components with complex features. However, the long-term integrity of these components is uncertain, since AM parts have defects such as pores and rough surfaces. In this work, an analytical model was developed to determine the impact of defects, and a novel bending fatigue test was used to determine the fatigue life of channeled specimens. The analytical model, based off the theory of critical distances, investigates coupled pores and predicts their potential for fatigue failure. This resulted in a maximum allowable pore size and spacing recommendation for coupled defects. Additionally, specimens with through channels …

Application Of Survival Analysis Techniques To Probabilistic Assessment Of Fatigue In Steel Bridges, Azam Nabizadehdarabi

Theses and Dissertations

The fatigue of engineering materials under repetitive loading is a significant issue affecting the design and durability of components and systems in a variety of engineering-related applications including civil, mechanical, aerospace, automotive, and electronics. Many factors can affect the service life of a component or system under repetitive loading, such as the type of structure, loading, connection details, stress state, peak stress or stress range, surface condition, temperature, and environmental exposure. Currently, there is no comprehensive probabilistic approach that can systematically address all the factors that contribute to fatigue on a single mathematical platform. However, advanced analysis techniques developed for …

Estimation Of The Fatigue Life Of Additively Manufactured Metallic Components Using Modified Strain Life Parameters Based On Surface Roughness, Peter Grohs

Masters Theses

In this study, a method is developed to estimate the effects of surface roughness on the fatigue life of additively manufactured titanium Ti6Al4V, aluminum 7075–T6, and steel 4340 alloys through modified strain life parameters using finite element analysis (FEA). This method is highly beneficial to the fatigue analysis of as-built additively manufactured metal components, which possess rough surfaces that reduce fatigue life significantly but are challenging to analyze directly using finite element simulation because of complex geometries, i.e., modeling an exact surface profile is arduous.

An effective stress concentration factor, incorporating roughness data, is defined to quantify their effects on …

In Situ Measurement Of Fatigue Induced Crack Growth In Inconel 718 Using Direct Current Potential Drop Method, Joel C. Lindsay

Graduate Theses, Dissertations, and Problem Reports

With recent advances in air breathable engines comes more extreme temperature environments that engine components must tolerate. During the design of these engines, it is necessary to understand how material fatigue failures occur at these new, higher operating temperatures. In providing understanding, the following fundamental study focuses on the statistical nature of crack jumps (changes in crack length over time) during fatigue in a polycrystalline nickel-based superalloy, Inconel 718 (IN718). In situ measurement of the crack length at several loading conditions were conducted using a direct current potential drop (DCPD) measurement method. Experimental data was collected at six different fatigue …

Development Of A Rapid Fatigue Life Testing Method For Reliability Assessment Of Flip-Chip Solder Interconnects, Cody Jackson Marbut

Graduate Theses and Dissertations

The underlying physics of failure are critical in assessing the long term reliability of power packages in their intended field applications, yet traditional reliability determination methods are largely inadequate when considering thermomechanical failures. With current reliability determination methods, long test durations, high costs, and a conglomerate of concurrent reliability degrading threat factors make effective understanding of device reliability difficult and expensive. In this work, an alternative reliability testing apparatus and associated protocol was developed to address these concerns; targeting rapid testing times with minimal cost while preserving fatigue life prediction accuracy. Two test stands were fabricated to evaluate device reliability …

Numerical Evaluation Of Energy Release Rate At Material Interfaces For Fatigue Life Predictions, Robert L. Hendrickson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Composite materials are becoming popular in almost all industries. Carbon-fiber and glass-fiber composites are used in aircraft, sports equipment, boats, prosthetics, and wind turbine blades. In all these applications, the composites are subjected to different loads. Loads can take the form of impact or cyclic/fatigue loading, both of which decrease the strength of composites as micro-cracks grow through the composite. Composite laminates are made up of fiber plies (thin layers of fiber) and the fibers are surrounded by a resin like epoxy. It is common for laminates to fail because of delamination growth (plies peeling apart). Small delaminations do not …

A Nanoindentation Study Of The Fatigue Properties Of Al/A-Si Core-Shell Nanostructures, Jason Steck

Mechanical Engineering Undergraduate Honors Theses

Nanostructure-textured surfaces can reduce friction and increase the reliability of micro- and nanoelectromechanical systems (NEMS/MEMS). For MEMS incorporating moving parts, the fatigue properties of nanostructures pose a challenge to their reliability in long-term applications. In this study, the fatigue behavior of hemispherical Al/a-Si core-shell nanostructures (CSNs), bare hemispherical Al nanodots, and a flat Al/a-Si layered thin film have been studied using nanoindentation and nano-scale dynamic mechanical analysis (nano-DMA) techniques. Fatigue testing with nano-DMA shows that the deformation resistance of CSNs persists through 5.0 × 10⁴ loading cycles at estimated contact pressures greater than 15 GPa. When the a-Si shell …

Determination Of Chemical Notch, KChem On Aluminum And Steel When Subjected Under Slow Strain Rate Test In Corrosive Environment, Joshua Teo Lee Kuok

Masters Theses

When designing for any mechanical components or system, the question would arise as to how the material would react to the loads subjected on it? Would the component survive its service load? How would it react to environmental corrosion? To answer these questions, the technique used in this thesis paper is the Slow Strain Rate Test (SSRT) method. Aluminum and steel were chosen as the material to be tested in this paper. Al 7075-T651, and Al 6061-T651 was chosen due to its wide range of application, high strength to weight ratio and ease of machinability. It is highly used in …

Studies On Woven Carbon/Vinyl Ester Composites: Environmental Effects, Joining And Hybridization, Ricardo Garcia

Open Access Theses & Dissertations

The incessant demand for fiber reinforced polymer composites, or FRPCs, in industrial applications which desire materials that possess high strength-to-weight ratios, generates a theory-to-practice void which must be filled with scientific research. In this Thesis, woven carbon/vinyl ester composites are studied under a wide spectrum of settings and conditions. The adverse effects of sea water environment and arctic temperatures on such mentioned composites are explored in the form of moisture uptake, impact on flexural modulus, strength and structural damage. It was found that sea water saturation in general degrades the flexural strength up to 19.45%, and arctic exposure and combined …

Final Design Report: Polymer Fatigue Characterization Test Method, Wyatt Ayling, Tyler Price, Brandon Stell, Michela Upson

Mechanical Engineering

Polylogix is a team dedicated to the design, build, and testing of a fatigue machine to simulate cyclic loading on a biomedical polymer. This project is sponsored by Endologix, Inc. to provide test data characterizing mechanical material properties of various formulations of polymer used in abdominal aortic aneurysm surgeries. With this project goal, the machine must be able to test the polymer at body conditions; these include a testing temperature of 37°C and a cycling frequency ranging from 1 Hz to 10 Hz. This report proposes the following solution to this design challenge: an AC motor-driven mechanism utilizing a planetary …

Dynamic Monitoring And Life Prediction Of Internal Strain-Gage Balances, David Leon Yoder

Masters Theses

Wind tunnel test customers continue to push the limits by producing air vehicle designs that produce high aerodynamic loads at the desired test conditions. These loads are a combination of steady aerodynamic, unsteady aerodynamic, and inertial forces. A methodology to monitor the health of a wind tunnel strain-gage balance has been developed. The objective of this methodology is to define the stress limits of the balance and monitor these limits so the balance can be safely tested without failure of the balance. A balance failure could result in costly damage to the wind tunnel model, support system, and the wind …