Engineering Mechanics Commons^™

Characterisation, Modelling And Simulation Of Flexible Polyurethane Foam, Conor Briody, Barry Duignan, Stephen Jerrams

Conference Papers

Flexible polyurethane foam is an open-celled polymeric material that exhibits strain rate and temperature effects. It has found various applications in areas including the packaging, medical, sports, aerospace and aeronautical industries. Polyurethane foam is ubiquitous in seating applications and finds particular use in specialised wheelchair seating where customised seating solutions are required which can provide proper comfort and support without the risk of developing pressure ulcers. Proper seating design is critical for users if this problem is to be avoided, but a lack of quantitative knowledge of this material’s behaviour has limited its effectiveness. The objectives of the work presented …

Me-Em Enewsbrief, June 2011, Department Of Mechanical Engineering-Engineering Mechanics, Michigan Technological University

Department of Mechanical and Aerospace Engineering eNewsBrief

No abstract provided.

Ultrasonic And Stereo-Optical Characterization Techniques For Applications In Mechanical Testing, Jonathan M. Hein

Department of Engineering Mechanics: Dissertations, Theses, and Student Research

This thesis considers methods developed based on ultrasonic reflections from interfaces and stereo-optical surface strain measurements to study the mechanical characterization of materials and bodies. The ultrasonic method is used to characterize wave speed and attenuation for highly attenuating samples. The stereo-optical strain measurements are used to characterize the effects of genes on mechanical properties of bone, and the dynamic characterization of blast waves in the UNL Shock Wave Trauma Mechanics facility.

A method is described and developed for characterizing the wave speed and attenuation spectrums from reflected waves from the contact surface with an unknown material. The method is …

Me-Em Enewsbrief, March 2011, Department Of Mechanical Engineering-Engineering Mechanics, Michigan Technological University

Department of Mechanical and Aerospace Engineering eNewsBrief

No abstract provided.

Me-Em 2011 Annual Report, Department Of Mechanical Engineering-Engineering Mechanics, Michigan Technological University

Department of Mechanical and Aerospace Engineering Annual Reports

Table of Contents

• ME-EM: 85 Years of Excellence
• Faculty & Staff
• Enrollment & Degrees
• Alumni
• Resources
• Graduates

Solving The Partial Differential Equation Of Vibrations With Interval Parameters Using The Interval Finite Difference Method, Brenda G. Medina

Open Access Theses & Dissertations

Accuracy and efficiency are among the main factors that drive today's innovative disciplines. As technology rapidly advances, efficiency takes on new meanings but what about accuracy? How accurate is accurate? Human error, uncertainties in measurement, and rounding errors are just some causes of inaccuracy. Interval Computations is an area that allows for such issues to be taken into account; for each measurement attained (for example), an interval can be built by considering the error associated with the measurement, and such an interval can be utilized in the mathematical computations of interest.

We consider the partial differential equation (PDE) of vibrations …

The Influence Of Pressure Relaxation On The Structure Of An Axial Vortex, Robert L. Ash, Irfan Zardadkhan, Allan J. Zuckerwar

Mechanical & Aerospace Engineering Faculty Publications

Governing equations including the effects of pressure relaxation have been utilized to study an incompressible, steady-state viscous axial vortex with specified far-field circulation. When sound generation is attributed to a velocity gradient tensor-pressure gradient product, the modified conservation of momentum equations that result yield an exact solution for a steady, incompressible axial vortex. The vortex velocity profile has been shown to closely approximate experimental vortex measurements in air and water over a wide range of circulation-based Reynolds numbers. The influence of temperature and humidity on the pressure relaxation coefficient in air has been examined using theoretical and empirical approaches, and …

Design Decisions Under Risk And Uncertainty, Sravya Thoomu

All Theses

In the contemporary world of engineering, engineers strive towards designing reliable and robust artifacts while considering and attempting to control manufacturing costs. In due course they have to deal with some sort of uncertainty. Many aspects of the design are the result of properties that are defined within some tolerances, of measurements that are appropriate, and of circumstances and environmental conditions that are out of their control. This uncertainty was typically handled by using factors of safety, and resulted in designs that may have been overly conservative. Therefore, understanding and handling the uncertainties is critical in improving the design, controlling …

Anomalous Loss Of Toughness Of Work Toughened Polycarbonate, Shawn E. Meagher

Department of Engineering Mechanics: Dissertations, Theses, and Student Research

Glassy polymers such as polycarbonate (PC) can be toughened through compressive plastic deformation. The increase in toughness is substantial, showing as much as a fifteen fold increase in the amount of dissipated energy during failure for samples compressed to 50% plastic strain. This toughness increase can be reversed through thermal aging at temperatures below the glass transition temperature (T_g = 147°C).

The combined effect of plastic compression and thermal aging has been studied using Charpy, Single Edge Notch Bending (SENB), and Compact Tension (CT) tests. The tests mapped the response of samples cut along different orientations relative to the …

Hybrid Nanomanufacturing Process For High-Rate Polymer Nanofiber Production, Chad T. Peterson

Department of Engineering Mechanics: Dissertations, Theses, and Student Research

Nanotechnology and nanomaterials have the potential to revolutionize existing and create entirely new industries. Unique physical, mechanical, chemical, and biological properties of nanomaterials have been extensively documented in the last two decades. However, most nanomaterials are discontinuous in nature, creating problems with their processing and manipulation into devices and raising health concerns. Continuous nanofibers represent an emerging class of nanomaterials with critical advantages to applications. Continuous nanofibers are readily produced by electrospinning process comprising spinning polymer solutions in high electric fields. Electrospinning is a very economic top-down nanomanufacturing process that has been used to produce ultrafine continuous nanofibers from several …

Me-Em Enewsbrief, December 2010, Department Of Mechanical Engineering-Engineering Mechanics, Michigan Technological University

Department of Mechanical and Aerospace Engineering eNewsBrief

No abstract provided.

Nanomanufacturing And Analysis Of Novel Integrated Continuous Nanofibers, John E. Hannappel

Department of Engineering Mechanics: Dissertations, Theses, and Student Research

Complex nanostructured materials have great potential for applications in many areas of nanotechnology. This potential is being unlocked by precise control of their nanoscale architecture and properties. Most current methods of creating these nanostructures are expensive and difficult to control, with the majority of techniques resulting in non-continuous nanostructures and nanoparticles. Electrospinning is an economic nanomanufacturing method resulting in continuous nanofibers. The method consists of spinning fiber-forming liquids in high electric fields. In this work, a modified electrospinning process was analyzed. The process utilized two concentric liquids that resulted in integrated continuous hollow or composite nanofibers. A new adjustable co-axial …

Me-Em Enewsbrief, September 2010, Department Of Mechanical Engineering-Engineering Mechanics, Michigan Technological University

Department of Mechanical and Aerospace Engineering eNewsBrief

No abstract provided.

Non-Contact Spatially Constrained Optical Scanning Methods Applied For Depth, Width And Gap Measurements, Konda Reddy Thotti Reddy

All Theses

The thesis presents the non-contact laser projection based systems utilized for quantifying the feature dimensions like width, depth and air gaps. Laser diode, Charge coupled device (CCD) and post-processing software using image processing tools are the major components of the non-contact measurement systems. The study involves two methods where the first method comprises of active laser-based triangulation and morphological edge detection for depth and width measurement applications. The second method uses edge detection technique and Dynamic Field of View (DFOV) for gap detection and tracking. Using the developed techniques, the case studies are conducted with smooth plastic fenders with induced …

Diffuse Ultrasonic Scattering In Advanced Composites, Christer Stenström

Department of Engineering Mechanics: Dissertations, Theses, and Student Research

Non destructive testing (NDT) is a noninvasive technique used for characterization and inspection of the integrity of objects. NDT is an important tool for research, manufacturing monitoring and in-service inspections. Ultrasonic testing is the most used NDT technique, which for advanced composites can identify several types of defects, like delamination and interlaminar cracks. Diffuse ultrasonics has shown to be able to extract information at the microscale of metals and therefore it is believed it can be used for advanced composites to extract microstructural information, i.e. at the level of fibers.

In this thesis, diffuse ultrasonic methods, together with spatial variance …

Combined Musculo-Skeletal Multi-Body Dynamics/Finite Element Analysis Of Several Ergonomics And Bio-Mechanics Problems, Xin Xie

All Theses

Within this thesis, two ergonomics (i.e. seating comfort and long-distance driving fatigue problems) and two structural bio-mechanics (i.e. femur-fracture fixation and radius-fracture fixation) problems are investigated using musculo-skeletal multi-body dynamics and finite element computational analyses.
Within the seating comfort problem analyzed, a complete-body finite element model is constructed and used to assess the effect of seat geometry and seating posture on the feel of comfort experienced by a seated human.
Within the long-distance driving fatigue problem, musculo-skeletal analysis is employed to assess the extent of fatigue experienced by a driver through the evaluation of level of activity of his/her various …

Determination Of Higher Order Coefficients For A Crack Parallel To An Interface, Venkata Lakshman Kolluru

All Theses

A general method based on the singular integral equations is developed to
computationally determine the higher order coefficients in mixed mode fracture
mechanics. These 'k' and 'T' coefficients are defined with respect to a polar coordinate
system centered at a crack tip, and give asymptotic expressions for stresses and
displacements according to the William's eigenfunction expansions,
(r, ) (2r) k f (n, ) k f (n, ) IIk
ij
II
n
Ik
ij
I
n
n 0
2
1
n
ij      



1
(0, ) (2 ) ( , ) ( , …

Ultracapacitor Heavy Hybrid Vehicle: Model Predictive Control Using Future Information To Improve Fuel Consumption, Seneca Schepmann

All Theses

This research is concerned with the improvement in the fuel economy of heavy transport vehicles through the use of high power ultracapacitors in a mild hybrid electric vehicle platform. Previous work has shown the potential for up to 15% improvement on a hybrid SUV platform, but preliminary simulations have shown the potential improvement for larger vehicles is much higher.
Based on vehicle modeling information from the high fidelity, forward-looking modeling and simulation program Powertrain Systems Analysis Toolkit (PSAT), a mild parallel heavy ultracapacitor hybrid electric vehicle model is developed and validated to known vehicle performance measures. The vehicle is hybridized …

Friction Measurement In Precision Glass Molding, Peiman Mosaddegh

All Dissertations

Extensive growth of state-of-the-art technologies has created a demand for high quality lenses and has driven the industry toward an inexpensive process for manufacturing of aspheric glass lenses called Precision Glass Molding (PGM). Finite Element Analysis (FEA) has been used to predict the right mold geometry. Having a realistic simulation to predict mold geometry depends on the correct model of material behavior and friction coefficient at elevated temperature.
Finding the static and dynamic coefficient of friction experimentally between two flat surfaces at elevated temperature is the subject of this research. The equipment used in this study was originally designed for …

Parametric Instabilities For Vibratory Energy Harvesting Under Harmonic, Time-Varying Frequency, And Random Excitations, Christopher Stabler

All Theses

This effort investigates and evaluates the prospect of using parametric instabilities for vibratory energy harvesting. To that end, we consider a parametrically-excited piezoelectric cantilever beam and study its performance as an energy harvester under i) fixed-frequency harmonic excitations, ii) time-varying frequency excitations, and iii) band-limited Gaussian noise. In the case of fixed-frequency excitations, we use the Method of Multiple Scales to obtain approximate analytical expressions for the steady-state response amplitude and instantaneous output power in the vicinity of the first principle parametric resonance. We show that the electromechanical coupling and load resistance play an important role in determining the output …

Electromechanical Modeling And Analysis Of A Self-Excited Micro-Power Generator, Amin Bibo

All Theses

Micro-power generators (MPGs) are compact, scalable, and low-maintenance energy harvesting devices that capture and transform wasted ambient energy into electricity.
Such devices, which are currently being researched as a possible replacement for batteries, can act as a power source to maintain and allow autonomous operations of
remote low-power consumption sensors. This thesis introduces a novel MPG which transforms wind energy into electricity via wind-induced self-excited oscillations
of piezoelectric cantilever beams. The operation concept of the device is simple: similar to music-playing harmonica that create tones via oscillations of reeds when
subjected to air blow, the proposed device uses flow-induced self-excited …

Infrared Thermography And Ultrasonic Inspection Of Adhesive Bonded Structures, Overview And Validity, Suhas Vedula

All Theses

The work focuses on establishing a relationship between two different techniques of Nondestructive testing, namely Infrared Thermography and Ultrasonic Inspection. The integration of the two testing techniques is done with an expectation to achieve accurate characterization and determination of internal defects in adhesive bonded structures.
Experiments are done on sandwich samples with defects using various ultrasonic testing methods like pulse-echo and immersion techniques. The results thus obtained are documented and location of the defects is marked. The same samples are then tested using Infrared thermography to visualize the defects.
The results obtained by both the methods are compared to check …

Fuzzy Logic Approach To Stability Control, Jeffery Anderson

All Theses

Traditional Electronic Stability Control (ESC) for automobiles is usually accomplished through the use of estimated vehicle dynamics from simplified models. Starting with the conventional two degree-of-freedom vehicle model, one can estimate the vehicle states from the driver steering input. From this estimate, vehicle sideslip angle can be found and this is generally used with a threshold value to initiate a control action. The input/output relationship of the model depends heavily on the accuracy of the parameters used and various means to correct model inaccuracies. Specifically, these models depend on the tire cornering stiffness which is prone to change with age …

Automation Of Non-Destructive Testing Techiniques Used For Finding Defects, Bhanu Singh

All Theses

This master thesis focuses on the automation and fusion of non-destructive testing methods. The research includes the fusion of non-destructive testing methods done with infrared micro-bolometer and ultrasonic transducers. A control system which utilized mechanical, electrical, electronic systems and computer aided technologies was developed. Conveyor belt system, PLC (programmable logic controller), XYZ mechanism and different sensors were utilized to automate the process of capturing images and a communication link was set up between thermal camera and system that controls the ultrasonic testing apparatus, to integrate the two techniques. The test results from the thermal camera were utilized in ultrasonic testing. …

Modeling And Optimization Of A Plug-In Hybrid Electric Vehicle, Venkat Vijay Kishore Turlapati

All Theses

Today, the world is faced with a situation where new technologies have to be developed to decrease the dependence on natural non-renewable resources. Each day, as the demand for non-renewable resources increases, it puts great pressure on the scientific fraternity to develop new technologies that are aimed at reducing this dependence.
Today's road traffic plays a major part in the energy consumption worldwide. Hence it is imperative that we develop environmentally friendly solutions to this problem that arises in the transportation sector. Hybrid vehicle is one of the alternatives that can be seen as a viable solution to this energy …

Induction Assisted Thermography For Inspection Of Micro Defects On Sheet Metals, Sree Pamidi

All Theses

The work focuses on Induction assisted Thermography as a non-contact and non-destructive method of Inspecting micro defects on sheet metals used for making automotive body panels. Induction heating as a source of excitation to elevate the temperatures of sheet metals for uniform heating and detect ability of the defect is the main objective of the study.
Experiments are done on sheet metal samples with defects using excitation techniques like Pulse and Electromagnetic Induction. The thermal images obtained from the infrared camera are used to quantitatively analyze the detect ability of defects on sheet metals. The limitations of using Pulse technique …

Design Method Development For The Design Of Traction Systems, Avinash Kolla

All Theses

The objective of this research is to develop a design method for rapid exploration of traction concepts primarily for off-road vehicles. Different approaches available to achieve this objective are discussed and compared, such as computational, analytical, and physical methods. Computational approaches are based on simulations performed using Finite Element Method (FEM), Discrete Element Method (DEM), and combined Finite Element-Discrete Element (FE-DE) methods. Analytical approaches are based on closed form mathematical models developed by previous researchers based on the theory of plasticity. Physical approaches include fabrication and testing of prototypes at different levels of abstraction. This thesis compares these different approaches …

Development Of A Finite Element Model To Predict The Behavior Of A Prototype Wheel On Lunar Soil, Marisa Orr

All Dissertations

The All-Terrain Hex-Limbed Extra-Terrestrial Explorer (ATHLETE) is a mobile lunar lander under development by the National Aeronautics and Space Administration's Lunar Architecture Team. While previous lunar missions have lasted only a few days, the ATHLETE is designed to last for 10 years, which will enable a sustained U.S. presence on the moon and exploration of the more treacherous regions which are not suitable for landing. Because the ATHLETE will carry entire astronaut habitats, its six wheels must be carefully designed to support a large load on soft lunar soil efficiently.
The purpose of this thesis is to develop a finite …

Modeling Of Cell Transfer And Process-Induced Cell Damage In Laser-Assisted Cell Direct Writing, Wei Wang

All Dissertations

Laser-assisted cell direct-write technique has been obtaining more and more attention in different biomaterial direct writing applications. A typical laser-assisted cell direct-write process can be divided into two main stages: the cell droplet ejection and cell droplet landing. The objective of this study is to model the cell mechanical profile during the cell droplet ejection and cell landing and further model the cell damage.
The possible cell damage during the droplet ejection process in laser-assisted cell direct writing may come from two different sources: the phase explosion-induced bubble expansion and the thermoelastic stress wave. The bubble expansion-induced stress wave is …

Investigation Of Subgrid-Scale Mixing And Turbulence-Chemistry Interaction In Turbulent Partially Premixed Flames Using Experimental Data, Jian Cai

All Dissertations

The filtered mass density function (FMDF) of mixture fraction, temperature and species used in large eddy simulation (LES) of turbulent combustion is studied experimentally using line images obtained in turbulent partially premixed methane flames (Sandia flames D and E). Cross-stream filtering is employed to obtain the FMDF and other filtered variables. The mean of the FMDF conditional on the subgrid-scale (SGS) scalar variance at a given location are found to vary from unimodal to bimodal, corresponding to quasi-equilibrium distributed reaction zones and laminar flamelets (including extinguished flamelets), respectively. The conditionally filtered mixture fraction dissipation for small SGS variances has a …