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Articles 181 - 210 of 305
Full-Text Articles in Engineering
A Weighted Least-Squares Method For Inverse Dynamic Analysis, Antonie J. Van Den Bogert, Anne Su
A Weighted Least-Squares Method For Inverse Dynamic Analysis, Antonie J. Van Den Bogert, Anne Su
Mechanical Engineering Faculty Publications
Internal forces in the human body can be estimated from measured movements and external forces using inverse dynamic analysis. Here we present a general method of analysis which makes optimal use of all available data, and allows the use of inverse dynamic analysis in cases where external force data is incomplete. The method was evaluated for the analysis of running on a partially instrumented treadmill. It was found that results correlate well with those of a conventional analysis where all external forces are known.
Mechanical Properties Of A Reinforced Composite Polymer Electrolyte Membrane And Its Simulated Performance In Pem Fuel Cells, Yaliang Tang, Ahmet Kusoglu, Anette M. Karlsson, Michael H. Santare, Simon Cleghorn, William B. Johnson
Mechanical Properties Of A Reinforced Composite Polymer Electrolyte Membrane And Its Simulated Performance In Pem Fuel Cells, Yaliang Tang, Ahmet Kusoglu, Anette M. Karlsson, Michael H. Santare, Simon Cleghorn, William B. Johnson
Mechanical Engineering Faculty Publications
The hygro-thermo-mechanical properties and response of a class of reinforced perfluorosulfonic acid membranes (PFSA), that has potential application as an electrolyte in polymer fuel cells, are investigated through both experimental and numerical modeling means. A critical set of material properties, including Young’s modulus, proportional limit stress, break stress and break strain, is determined for a range of temperature and humidity levels in a custom-built environmental test apparatus. The swelling strains are also determined as functions of temperature and humidity level. To elucidate the mechanical response and the potential effect these properties have on the mechanical durability, mechanics-based simulations are performed …
Experimental Test And Cost Analysis Of Residential Solar Water Heaters, Sai Mahesh Dharanikota
Experimental Test And Cost Analysis Of Residential Solar Water Heaters, Sai Mahesh Dharanikota
ETD Archive
Non renewable energy sources have been diminishing in the recent times.Renewable energy is abundant in nature, but the use of it is very low.Lowering the energy consumption and using renewable energy, thereby decreasing the use of fossil fuels and nuclear energy would have a positive impact on our environment. The use of solar energy as an alternate resource is discussed in this research. The solar water heater is tested for its recovery rates, under normal solar radiation in static testing. The effect of solar radiation in increasing the temperature of water is studied and discussed. The solar water heater is …
Effect Of Adding A Regenerator To Kornhauser's Mit "Two-Space" Test Rig, Praveen Gidugu
Effect Of Adding A Regenerator To Kornhauser's Mit "Two-Space" Test Rig, Praveen Gidugu
ETD Archive
A 3-space solution domain (gas spring + heat exchanger + regenerator) is adapted from the 2-space solution domain (gas spring + heat exchanger) in Kornhauser MIT test rig [25] by modifying the heat exchanger space to include a porous regenerator system. A thermal non-equilibrium porous-media model is employed for the regenerator. Extensive numerical simulations of the fluid flow and heat transfer phenomena under conditions of oscillating pressure and oscillating fluid flow inside the 3-space solution domain were performed using 1-D Sage and 2-D Fluent numerical codes. 3-space results of temperature, pressure and surface heat transfer variations, pressure-volume diagrams, energy conservation …
Radiation View Factors Between A Disk And The Interior Of A Class Of Axisymmetric Bodies Including Converging Diverging Rocket Nozzles, Mark Richard Murad
Radiation View Factors Between A Disk And The Interior Of A Class Of Axisymmetric Bodies Including Converging Diverging Rocket Nozzles, Mark Richard Murad
ETD Archive
A general symbolic exact analytic solution is developed for the radiation view factors including shadowing by the throat between a divergence thin gas disk between the combustion chamber and the beginning of the rocket nozzle radiating energy to the interior downstream of the nozzle contour for a class of coaxial axisymmetric converging diverging rocket nozzles. The radiation view factors presented in this thesis for the projection which are blocked or shadowed through the throat radiating downstream to the contour have never been presented before in the literature. It was found that the curvature of the function of the contour of …
Application Of Reverse Engineering And Rapid Prototyping To Casting, Venkat Deepak Kolar
Application Of Reverse Engineering And Rapid Prototyping To Casting, Venkat Deepak Kolar
ETD Archive
The automotive industry has an increasing need for the re manufacturing of spare parts through reverse engineering. In this thesis we will review the techniques used in Fused Deposition Modeling system for the reverse engineering of vintage automotive parts. The objective of the project is to be able to generate part-to-CAD and CAD-to-part reconstruction of the original part for future usage. These newly created 3D models will be added to the 3D Part Database. The integration of reverse engineering and rapid prototyping is being used for getting product to the market quickly by resolving a long-standing conflict between design and …
Experimental Testing And Performance Analysis Of "Room Air Cleaners", Pavan Kumar Mudiya
Experimental Testing And Performance Analysis Of "Room Air Cleaners", Pavan Kumar Mudiya
ETD Archive
HMI industries are the manufacture of the air cleaners and vacuum cleaners, in which a solution is adapted for the current model of the volute to the new design of the volute in order to calculate the "Clean Air Delivery rate" and qualify for the "Energy Star requirements". For the above model to be employed as a Energy Star certificate, a test rig was made in which "air velocity" and "flow rate" was calculated for the three different air cleaners in two cases i.e. (i) three different air cleaners with different filters and different rpm's (ii) three different air cleaners …
Probabilistic Finite Element Heat Transfer And Structural Analysis Of A Cone-Cylinder Pressure Vessel, Omar Haddad
Probabilistic Finite Element Heat Transfer And Structural Analysis Of A Cone-Cylinder Pressure Vessel, Omar Haddad
ETD Archive
Stress analysis of a cone-cylinder pressure vessel was computationally simulated by a finite element method and probabilistically evaluated in view of the several uncertainties in the performance parameters. Cumulative distribution functions and sensitivity factors were computed for overall Von Mises stresses due to the structural and thermodynamic random variables. These results can be used to quickly identify the most critical design variables in order to optimize the design and make it cost effective. The analysis leads to the selection of the appropriate measurements to be used in structural and heat transfer analysis and to the identification of both the most …
Mathematical Analysis Of A Geothermal System, Ivan P. Erceg
Mathematical Analysis Of A Geothermal System, Ivan P. Erceg
ETD Archive
The issue being examined is to design a more economical and efficient therefore superior geothermal system than currently in use in industry. Current geothermal systems are designed and built 300 feet into the ground. After researching ground temperature gradients for Ohio we found out that below 10 feet of depth, the temperature varies by 1 degree Fahrenheit per 100 feet depth. Our goal is to utilize the heat as close to the surface as possible and greatly reduce the need to dig so deeply into the ground. The procedure used to go about designing a superior geothermal system is to …
Road Surface Condition Detection And Identification And Vehicle Anti-Skid Control, Maosheng Ye
Road Surface Condition Detection And Identification And Vehicle Anti-Skid Control, Maosheng Ye
ETD Archive
Road surface condition is greatly dependent on the surface's friction coefficient. The abrupt change of the coefficient results in variation of wheel slip which likely leads to vehicle instability. Vehicle steering model and the dynamic equations for four-wheel drive vehicle is developed. A new observer, called Extended State Observer (ESO) is used to estimate the longitudinal velocity, lateral velocity and yaw rate, and more importantly an additional quantity known as system dynamics. A trained neural network was employed to help determine the friction coefficient. Fuzzy logic was employed to quickly detect the change of road surface condition and further classify …
A Kinematics Based Tolerance Analysis Of Mechanisms, Shahrbanoo Biabnavi Farkhondeh
A Kinematics Based Tolerance Analysis Of Mechanisms, Shahrbanoo Biabnavi Farkhondeh
ETD Archive
A kinematic based tolerance analysis of mechanisms is presented in this thesis. It is shown that standard kinematic analysis can be used for obtaining closed-form explicit formulations for tolerance analysis of mechanisms. It is proposed that the manufacturing tolerances are accounted for by incorporating fictitious sliding members in the rigid links, thereby allowing them to either "grow" or "shrink" along the lines of their pin connections. The virtual expansions or contractions of these fictitious sliders are captured in the kinematic equations by taking the differentials of the magnitudes of the vectors that define the length of rigid links having dimensional …
Modeling Of Transient Thrust Of A Two Phase Propellant Tank, Karthik Mellechervu
Modeling Of Transient Thrust Of A Two Phase Propellant Tank, Karthik Mellechervu
ETD Archive
This thesis develops a model to predict various time-varying quantities associated with the evacuation of a pressurized container through a nozzle. The container is part of a satellite propulsion prototype used to study attitude control. Variables of interest include the thrust and mass of fluid in the tank as functions of time. A mathematical model based on transient expressions for mass and energy conservation is derived for a two-phase system representative of the conditions of the fluid inside the tank
Multiplexed Control Of Smart Structure Using Piezoelectric Actuators, Kumar S. Nale
Multiplexed Control Of Smart Structure Using Piezoelectric Actuators, Kumar S. Nale
ETD Archive
Active control of smart structures containing a large number of actuators and sensors presents a tradeoff between increased system performance and the cost and bulk of the required hardware and computational resources. A technique called multiplexed control offers advantages when software and hardware resources are scarce and performance specifications call for a large number of actuators and sensors. In structural control applications, in particular those using smart materials, it is often desirable to increase the number of actuators to enhance controllability.The focus of this research is to demonstrate real-time multiplexing on the hardware side of the actively controlled structure. Multiplexing …
Effect Of Axial Oscillation On Performance Of Hydrodynamic Journal Bearings, Thomas Wirsing
Effect Of Axial Oscillation On Performance Of Hydrodynamic Journal Bearings, Thomas Wirsing
ETD Archive
The hydrodynamic coefficients of a journal bearing set with the bearing subjected to axial oscillation are determined in this work. The Navier-Stokes equations were used to account for the axial component of the relative motion between the journal and the bearing. Numerical solution of the Navier-Stokes equations yielded the pressure distribution within the cavity of the bearing. This pressure distribution was then integrated over the surface of the bearing to obtain the two orthogonal force components. The derivatives of these force components were then taken with respect to the displacement and velocity of the journal that are co-linear with these …
Motion Control Of An Open Container With Slosh Constraints, Kedar B. Karnik
Motion Control Of An Open Container With Slosh Constraints, Kedar B. Karnik
ETD Archive
General motion control of conveyor belts does not present difficulties. When the conveyor belt carries open containers filled with liquid, significant analysis needs to be carried out to design controllers. The objective of this thesis was to design a control system which will allow an open container filled with liquid to be transferred between two stations as fast as possible and without excessive slosh causing the liquid to spill out of the container. This control problem has applications to industrial processing facilities, where open containers are carried by a conveyor belt. The speed at which the open container can be …
Development Of Effective Balancing Procedure For Ct Scanner, Jeremy David Pettinato
Development Of Effective Balancing Procedure For Ct Scanner, Jeremy David Pettinato
ETD Archive
Since the beginning of medical organizations, engineering departments have introduced new innovative ideas and designs to advance image quality. In the case of a CT scanner, one of the largest and most cost effective ways to achieve superior image quality is through a well balanced rotating array. The focus of this thesis is the development of a balancing procedure which will effectively balance a CT scanner rotating array. Rigid rotor (dynamic) balancing techniques are utilized in order to balance the Philips CT scanner rotor. Upon completion of the dynamic balancing of the CT scanner rotor a new an innovative way …
Health Monitoring Of Cracked Rotor Systems Using External Excitation Techniques, Adam C. Wróblewski
Health Monitoring Of Cracked Rotor Systems Using External Excitation Techniques, Adam C. Wróblewski
ETD Archive
Cracked rotors present a significant safety and loss hazard in nearly every application of modern turbomachinery. This thesis focuses on the health monitoring, modeling, and analysis of machines with transverse breathing cracks, which open and close due to the self-weight of the rotor. After considering the modeling of cracked rotors, the thesis investigates an active structural health monitoring approach, focusing on the application of an active magnetic actuator to apply a specially designed external force excitation to the rotating shaft. Extensive experimental data has been collected and analyzed utilizing advanced diagnostic techniques. The presented results demonstrate that the use of …
Damage Detection Of Rotors Using Magnetic Force Actuator: Analysis And Experimental Verification, Alexander Hans Pesch
Damage Detection Of Rotors Using Magnetic Force Actuator: Analysis And Experimental Verification, Alexander Hans Pesch
ETD Archive
The ability to monitor the structural health of rotordynamic systems is becoming increasingly important as critical components continue to be used despite aging and the associated potential for damage accumulation. The aim of this thesis is to investigate a novel structural health monitoring approach for the detection of damage in rotating shafts, which utilizes a magnetic force actuator for applying multiple types of force inputs on to a rotating structure for analysis of resulting outputs. The magnetic actuator will be used in conjunction with conventional support bearings and also be applied to rotor under full magnetic levitation. The results of …
Multiplexed Predictive Control Of A Large Commercial Turbofan Engine, Hanz Richter, Anil V. Singaraju, Jonathan S. Litt
Multiplexed Predictive Control Of A Large Commercial Turbofan Engine, Hanz Richter, Anil V. Singaraju, Jonathan S. Litt
Mechanical Engineering Faculty Publications
Model predictive control is a strategy well-suited to handle the highly complex, nonlinear, uncertain, and constrained dynamics involved in aircraft engine control problems. However, it has thus far been infeasible to implement model predictive control in engine control applications, because of the combination of model complexity and the time allotted for the control update calculation. In this paper, a multiplexed implementation is proposed that dramatically reduces the computational burden of the quadratic programming optimization that must be solved online as part of the model-predictive-control algorithm. Actuator updates are calculated sequentially and cyclically in a multiplexed implementation, as opposed to the …
Helical Axes Of Skeletal Knee Joint Motion During Running, Antonie J. Van Den Bogert, C. Reinschmidt, A. Lundberg
Helical Axes Of Skeletal Knee Joint Motion During Running, Antonie J. Van Den Bogert, C. Reinschmidt, A. Lundberg
Mechanical Engineering Faculty Publications
The purpose of this study was to determine the changes in the axis of rotation of the knee that occur during the stance phase of running. Using intracortical pins, the three-dimensional skeletal kinematics of three subjects were measured during the stance phase of five running trials. The stance phase was divided into equal motion increments for which the position and orientation of the finite helical axes (FHA) were calculated relative to a tibial reference frame. Results were consistent within and between subjects. At the beginning of stance, the FHA was located at the midepicondylar point and during the flexion phase …
Creating A Reinforcement Learning Controller For Functional Electrical Stimulation Of A Human Arm, Philip S. Thomas, Michael Branicky, Antonie Van Den Bogert, Kathleen Jagodnik
Creating A Reinforcement Learning Controller For Functional Electrical Stimulation Of A Human Arm, Philip S. Thomas, Michael Branicky, Antonie Van Den Bogert, Kathleen Jagodnik
Mechanical Engineering Faculty Publications
Clinical tests have shown that the dynamics of a human arm, controlled using Functional Electrical Stimulation (FES), can vary significantly between and during trials. In this paper, we study the application of Reinforcement Learning to create a controller that can adapt to these
changing dynamics of a human arm. Development and tests were done in simulation using a two-dimensional arm model and Hill-based muscle dynamics. An actor-critic architecture is used with artificial neural networks for both the actor and the critic. We begin by training it using a Proportional Derivative (PD) controller as a supervisor. We then make clinically relevant …
On Internal Cone Cracks Induced By Conical Indentation In Brittle Materials, J. Yan, Anette M. Karlsson, X. Chen
On Internal Cone Cracks Induced By Conical Indentation In Brittle Materials, J. Yan, Anette M. Karlsson, X. Chen
Mechanical Engineering Faculty Publications
The conditions for cone cracks to develop due to a conical indentation are investigated. Axisymmetric numerical simulations, based on the finite element method, are conducted, assuming a linear-elastic, perfectly plastic material. A superposition scheme is employed to simulate a range of crack geometries, including various lengths and orientations. The results indicate that the class of cracks investigated is prone to develop internally in brittle materials. Based on a reversed analysis, a new technique is proposed for measuring the fracture toughness in bulk material and thick coatings through one simple indentation test when the cone crack appears.
The Effect Of Tibiofemoral Loading On Proximal Tibiofibular Joint Motion, Jacob Scott, Ho Lee, Wael Barsoum, Antonie J. Van Den Bogert
The Effect Of Tibiofemoral Loading On Proximal Tibiofibular Joint Motion, Jacob Scott, Ho Lee, Wael Barsoum, Antonie J. Van Den Bogert
Mechanical Engineering Faculty Publications
The human proximal tibiofibular joint (PTFJ) and its relationship to overall knee joint mechanics have been largely unexplored. This study describes force/displacement data from experiments done on four human cadaveric knee specimens and general conclusions obtained with the help of a statistical modeling technique. Specimens were rigidly affixed at the tibia to a force plate and the femur was attached to a custom made device allowing for manual load application. Motion of the fibular head was tracked relative to the tibial plateau by means of reflective markers and a high speed digital camera synchronized with the force plate data stream. …
On The Reference Length And Mode Mixity For A Bimaterial Interface, A. Agrawal, Anette M. Karlsson
On The Reference Length And Mode Mixity For A Bimaterial Interface, A. Agrawal, Anette M. Karlsson
Mechanical Engineering Faculty Publications
We investigate properties that govern interfacial fracture within the framework of linear elastic fracture mechanics, including interfacial fracture toughness, mode mixity,and the associated reference length. The reference length describes the arbitrary location where the mode mixity is evaluated, ahead ofthe crack tip, in a bimaterial system. A method for establishing a reference length that is fixed for a given bimaterial system is proposed. This is referred to as the“characteristic reference length,” with the associated “characteristic mode mixity.” The proposed method is illustrated with an experimental investigation, utilizing a four-point bend test of a bimaterial system.
Multiaxial Thermo-Mechanical Fatigue On Material Systems For Gas Turbines, M. Bartsch, B. Baufeld, M. Henzelmann, Anette M. Karlsson, S. Dalkilic, L. Chernova
Multiaxial Thermo-Mechanical Fatigue On Material Systems For Gas Turbines, M. Bartsch, B. Baufeld, M. Henzelmann, Anette M. Karlsson, S. Dalkilic, L. Chernova
Mechanical Engineering Faculty Publications
Material systems made from nickel based superalloys with protective coatings have been tested in thermo-mechanical fatigue with superposed thermal gradients, which generated multiaxial stress states. The testing conditions were selected for simulating the fatigue loading in the wall of an internally cooled gas turbine blade of an aircraft engine. After thermo-mechanical testing the damage behaviour of the materials has been investigated by means of microscopic methods. The laboratory experiments have been accompanied by numerical simulations. Based on the results of the simulations and observed damage features the test parameters in subsequent laboratory tests have been controlled to facilitate the validation …
Mechanical Behavior Of Fuel Cell Membranes Under Humidity Cycles And Effect Of Swelling Anisotropy On The Fatigue Stresses, Ahmet Kusoglu, Anette M. Karlsson, Michael H. Santare, Simon Cleghorn, William B. Johnson
Mechanical Behavior Of Fuel Cell Membranes Under Humidity Cycles And Effect Of Swelling Anisotropy On The Fatigue Stresses, Ahmet Kusoglu, Anette M. Karlsson, Michael H. Santare, Simon Cleghorn, William B. Johnson
Mechanical Engineering Faculty Publications
The mechanical response of proton exchange membranes in a fuel cell assembly is investigated under humidity cycles at a constant temperature (85°C). The behavior of the membrane under hydration–dehydration cycles is simulated by imposing a humidity gradient from the cathode to the anode. Linear elastic, plastic constitutive behavior with isotropic hardening and temperature and humidity dependent material properties are utilized in the simulations for the membrane. The evolution of the stresses and plastic deformation during the humidity cycles are determined using finite element analysis for two clamping methods and various levels of swelling anisotropy. The membrane response strongly depends on …
Review Of Rotordynamics, Jerzy T. Sawicki
Review Of Rotordynamics, Jerzy T. Sawicki
Mechanical Engineering Faculty Publications
Book Review of Rotordynamics, by Agnieszka (Agnes) Muszynska. CRC Press, Taylor & Francis Group, Boca Raton, FL, 2005, 1128 pp., ISBN: 0-8247-2399-6
Modeling And Performance Evaluation Of Machining Spindle With Active Magnetic Bearings, Jerzy T. Sawicki, Eric H. Maslen, Kenneth R. Bischof
Modeling And Performance Evaluation Of Machining Spindle With Active Magnetic Bearings, Jerzy T. Sawicki, Eric H. Maslen, Kenneth R. Bischof
Mechanical Engineering Faculty Publications
Active magnetic bearings (AMBs) are increasingly employed in the machine tool industry to exploit their advantages over classical bearings such as high speed capability, rotation accuracy, high stiffness, and accurate displacement tracking capability. Furthermore, the possibility of on-line monitoring of the machining process (e.g., cutting force measurement, tool wear) makes AMB spindles very appealing to the High-Speed Machining (HSM) industry. Despite significant progress already reached in HSM technology, there remain numerous open challenges in modeling and control of magnetic bearings as applied to machining spindles. These include optimum control given AMB magnetic saturation levels, management of nonlinear effects, reduction of …
Determining Plastic Properties Of A Material With Residual Stress By Using Conical Indentation, J. Yan, Anette M. Karlsson, X. Chen
Determining Plastic Properties Of A Material With Residual Stress By Using Conical Indentation, J. Yan, Anette M. Karlsson, X. Chen
Mechanical Engineering Faculty Publications
Instrumented indentation is a popular method for determining mechanical properties in engineering materials. However, there are several shortcomings and challenges involved with correctly interpreting the test results. We propose here a unified method for evaluating instrumented indentation testing conducted on a material that exhibits both strain hardening under yielding and which is subjected to uniform, equi-biaxial residual stresses. The proposed method is based on extensive finite element simulations that relate the parameter-space spanned by Young’s modulus, yield strength, strain hardening and residual stress, to the response from the indentation test. Based on reverse analysis, the proposed method can be used …
Determining Equi-Biaxial Residual Stress And Mechanical Properties From The Force-Displacement Curves Of Conical Microindentation, J. Yan, X. Chen, Anette M. Karlsson
Determining Equi-Biaxial Residual Stress And Mechanical Properties From The Force-Displacement Curves Of Conical Microindentation, J. Yan, X. Chen, Anette M. Karlsson
Mechanical Engineering Faculty Publications
An alternative, improved method to determine mechanical properties from indentation testing is presented. This method can determine the elastic modulus, yield strength and equi-biaxial residual stress from one simple test. Furthermore,the technique does not require the knowledge of the contact area during indentation, a parameter that is hard to determine for highly elastic material. The evaluation technique is based on finite element analyses, where explicit formulations are established to correlate the parameter groups governing indentation on stressed specimens.