Engineering Commons^™

Effective Modulus Of Cracked Bodies: A Finite Element Analysis, Alan Thomas Varughese

Theses and Dissertations--Mechanical Engineering

This thesis considers how cracks in an elastic body can alter the body’s elastic properties. In the present study the elastic property of note is the elastic or young’s modulus. It is desired to investigate to what extent the number and orientation of cracks can cause a reduction in the elastic modulus. Because of the complex nature of the elastic fields resulting from multiple cracks interacting together in a finite geometry an analytical solution is not possible or considered. Rather the Finite Element Method is used to determine the elastic response to a body with many cracks. This provides a …

A Model-Based Approach For Estimation Of Changes In Lumbar Segmental Kinematics Associated With Alterations In Trunk Muscle Forces, Iman Shojaei, Navid Arjmand, Judith R. Meakin, Babak Bazrgari

Biomedical Engineering Faculty Publications

The kinematics information from imaging, if combined with optimization-based biomechanical models, may provide a unique platform for personalized assessment of trunk muscle forces (TMFs). Such a method, however, is feasible only if differences in lumbar spine kinematics due to differences in TMFs can be captured by the current imaging techniques. A finite element model of the spine within an optimization procedure was used to estimate segmental kinematics of lumbar spine associated with five different sets of TMFs. Each set of TMFs was associated with a hypothetical trunk neuromuscular strategy that optimized one aspect of lower back biomechanics. For each set …

Analysis Of Underground Coal Mine Structures Subjected To Dynamic Events, Brooklynn Yonts

Theses and Dissertations--Mining Engineering

Underground coal mine explosions pose a significant threat to infrastructure such as mine seals and refuge alternative chambers. After a mine seal failed in the Sago mine disaster, which took the life of 12 miners, design requirements were reexamined and improved. However, most research being completed on the analysis of mine structures during an explosive event focuses solely on peak pressure values, while ignoring the impact of pressure duration. This study investigates the impact pressure duration, waveform shape, and impulse have on structural displacement, while also exploring what pressures and duration can be expected during a mine explosion. Additionally, the …

Computational Sensitivity Investigation Of Hydrogel Injection Characteristics For Myocardial Support, Hua Wang, Christopher B. Rodell, Madonna E. Lee, Neville N. Dusaj, Joseph H. Gorman Iii, Jason A. Burdick, Robert C. Gorman, Jonathan F. Wenk

Mechanical Engineering Faculty Publications

Biomaterial injection is a potential new therapy for augmenting ventricular mechanics after myocardial infarction (MI). Recent in vivo studies have demonstrated that hydrogel injections can mitigate the adverse remodeling due to MI. More importantly, the material properties of these injections influence the efficacy of the therapy. The goal of the current study is to explore the interrelated effects of injection stiffness and injection volume on diastolic ventricular wall stress and thickness. To achieve this, finite element models were constructed with different hydrogel injection volumes (150 µL and 300 µL), where the modulus was assessed over a range of 0.1 kPa …

Finite Element Analysis Of The Contact Deformation Of Piezoelectric Materials, Ming Liu

Theses and Dissertations--Chemical and Materials Engineering

Piezoelectric materials in the forms of both bulk and thin-film have been widely used as actuators and sensors due to their electromechanical coupling. The characterization of piezoelectric materials plays an important role in determining device performance and reliability. Instrumented indentation is a promising method for probing mechanical as well as electrical properties of piezoelectric materials.

The use of instrumented indentation to characterize the properties of piezoelectric materials requires analytical relations. Finite element methods are used to analyze the indentation of piezoelectric materials under different mechanical and electrical boundary conditions.

For indentation of a piezoelectric half space, a three-dimensional finite element …

Cryogenic Machining And Burnishing Of Az31b Magnesium Alloy For Enhanced Surface Integrity And Functional Performance, Zhengwen Pu

Theses and Dissertations--Mechanical Engineering

Surface integrity of manufactured components has a critical impact on their functional performance. Magnesium alloys are lightweight materials used in the transportation industry and are also emerging as a potential material for biodegradable medical implants. However, the unsatisfactory corrosion performance of Mg alloys limits their application to a great extent. Surface integrity factors, such as grain size, crystallographic orientation and residual stress, have been proved to remarkably influence the functional performance of magnesium alloys, including corrosion resistance, wear resistance and fatigue life.

In this dissertation, the influence of machining conditions, including dry and cryogenic cooling (liquid nitrogen was sprayed to …

Analysis Of Loads And Settlements For Reinforced Concrete Culverts, David L. Allen, Bobby W. Meade

Kentucky Transportation Center Research Report

Three primary factors in considering the loads on, and therefore the design of, underground conduits are: bedding conditions, trench configuration, and use of the "imperfect trench." Models of varied conditions are analyzed using a finite element program and the results compared to data obtained at instrumented sites of similar conditions. Presented herein are charts developed from these analyses which will facilitate future design of culverts. Also presented are recommendations for design criteria and construction procedures.