Open Access. Powered by Scholars. Published by Universities.®
- Discipline
-
- Biomechanical Engineering (76)
- Biomedical Engineering and Bioengineering (12)
- Materials Science and Engineering (9)
- Electrical and Computer Engineering (7)
- Aerospace Engineering (6)
-
- Computer-Aided Engineering and Design (5)
- Biomechanics and Biotransport (4)
- Chemical Engineering (4)
- Acoustics, Dynamics, and Controls (3)
- Membrane Science (3)
- Computer Engineering (2)
- Controls and Control Theory (2)
- Energy Systems (2)
- Engineering Science and Materials (2)
- Heat Transfer, Combustion (2)
- Applied Mechanics (1)
- Biomaterials (1)
- Civil and Environmental Engineering (1)
- Computer and Systems Architecture (1)
- Dynamics and Dynamical Systems (1)
- Environmental Engineering (1)
- Manufacturing (1)
- Medical Sciences (1)
- Medicine and Health Sciences (1)
- Ocean Engineering (1)
- Optics (1)
- Physical Sciences and Mathematics (1)
- Physics (1)
- Keyword
-
- Mechanical Engineering (18)
- Engineering (12)
- Biomechanics (10)
- Heat -- Transmission (9)
- Simulation (9)
-
- Finite element method (8)
- Optimal control (7)
- Finite element analysis (6)
- Materials Science (6)
- Rotors -- Dynamics (6)
- Control (5)
- Design (5)
- Robotics (5)
- CFD (4)
- Computational fluid dynamics (4)
- Magnetic bearings (4)
- Musculoskeletal modeling (4)
- Rotors (4)
- Spark Plasma Sintering (4)
- Thermal stresses (4)
- Vibration (4)
- Active magnetic bearing (3)
- Actuators (3)
- Composite materials (3)
- Functional electrical stimulation (FES) (3)
- Gait (3)
- Heat transfer (3)
- Mechanical engineering (3)
- Model (3)
- Modeling (3)
- Publication Year
- Publication
- Publication Type
Articles 31 - 60 of 321
Full-Text Articles in Mechanical Engineering
A Model-Based Approach To Predict Neuromuscular Control Patterns That Minimize Acl Forces During Jump Landing, Dieter Heinrich, Antonie J. Van Den Bogert, Robert Csapo, Werner Nachbauer
A Model-Based Approach To Predict Neuromuscular Control Patterns That Minimize Acl Forces During Jump Landing, Dieter Heinrich, Antonie J. Van Den Bogert, Robert Csapo, Werner Nachbauer
Mechanical Engineering Faculty Publications
Jump landing is a common situation leading to knee injuries involving the anterior cruciate ligament (ACL) in sports. Although neuromuscular control is considered as a key injury risk factor, there is a lack of knowledge regarding optimum control strategies that reduce ACL forces during jump landing. In the present study, a musculoskeletal model-based computational approach
is presented that allows identifying neuromuscular control patterns that minimize ACL forces during jump landing. The approach is demonstrated for a jump landing maneuver in downhill skiing, which is one out of three main injury mechanisms in competitive skiing.
Solar Thermal Dish Storage System Project: A Novel Receiver Experiment Model, Forrest Osborn
Solar Thermal Dish Storage System Project: A Novel Receiver Experiment Model, Forrest Osborn
Undergraduate Research Posters 2021
Solar energy utilizes sunlight to generate electricity but inefficiencies in energy storage limits this technology. Transferring sunlight into thermal energy can contribute to solve this problem. The goal of this study was to determine feasibility of a heat exchanger to be used with an existing solar parabolic dish. For this purpose, a heat gun was used to measure the thermal properties of a novel receiver design. This system was used to analyze different receiver configurations for a copper tube containing water as a heat transfer fluid. The inlet and outlet water temperatures and the effect of HTF flow rate were …
Efficient Trajectory Optimization For Curved Running Using A 3d Musculoskeletal Model With Implicit Dynamics, Marlies Nitschke, Eva Dorschky, Dieter Heinrich, Heiko Schlarb, Bjoern M. Eskofier, Anne D. Koelewijn, Antonie J. Van Den Bogert
Efficient Trajectory Optimization For Curved Running Using A 3d Musculoskeletal Model With Implicit Dynamics, Marlies Nitschke, Eva Dorschky, Dieter Heinrich, Heiko Schlarb, Bjoern M. Eskofier, Anne D. Koelewijn, Antonie J. Van Den Bogert
Mechanical Engineering Faculty Publications
Trajectory optimization with musculoskeletal models can be used to reconstruct measured movements and to predict changes in movements in response to environmental changes. It enables an exhaustive analysis of joint angles, joint moments, ground reaction forces, and muscle forces, among others. However, its application is still limited to simplified problems in two dimensional space or straight motions. The simulation of movements with directional changes, e.g. curved running, requires detailed three dimensional models which lead to a high-dimensional solution space. We
extended a full-body three dimensional musculoskeletal model to be specialized for running with directional changes. Model dynamics were implemented implicitly …
Achieving Practical Functional Electrical Stimulation-Driven Reaching Motions In An Individual With Tetraplegia, Derek Nathaniel Wolf
Achieving Practical Functional Electrical Stimulation-Driven Reaching Motions In An Individual With Tetraplegia, Derek Nathaniel Wolf
ETD Archive
Functional electrical stimulation (FES) is a promising technique for restoring the ability to complete reaching motions to individuals with tetraplegia due to a spinal cord injury (SCI). FES has proven to be a successful technique for controlling many functional tasks such as grasping, standing, and even limited walking. However, translating these successes to reaching motions has proven difficult due to the complexity of the arm and the goaldirected nature of reaching motions. The state-of-the-art systems either use robots to assist the FES-driven reaching motions or control the arm of healthy subjects to complete planar motions. These controllers do not directly …
Cnn-Based Estimation Of Sagittal Plane Walking And Running Biomechanics From Measured And Simulated Inertial Sensor Data, Eva Dorschky, Marlies Nitschke, Christine F. Martindale, Antonie J. Van Den Bogert, Anne D. Koelewijn, Bjoern M. Eskofier
Cnn-Based Estimation Of Sagittal Plane Walking And Running Biomechanics From Measured And Simulated Inertial Sensor Data, Eva Dorschky, Marlies Nitschke, Christine F. Martindale, Antonie J. Van Den Bogert, Anne D. Koelewijn, Bjoern M. Eskofier
Mechanical Engineering Faculty Publications
Machine learning is a promising approach to evaluate human movement based on wearable sensor data. A representative dataset for training data-driven models is crucial to ensure that the model generalizes well to unseen data. However, the acquisition of sufficient data is time-consuming and often infeasible. We present a method to create realistic inertial sensor data with corresponding biomechanical variables by 2D walking and running simulations. We augmented a measured inertial sensor dataset with simulated data for the training of convolutional neural networks to estimate sagittal plane joint angles, joint moments, and ground reaction forces (GRFs) of walking and running. When …
An Extensive Set Of Kinematic And Kinetic Data For Individuals With Intact Limbs And Transfemoral Prosthesis Users, Seyed Abolfazl Fakoorian, Arash Roshanineshat, Poya Khalaf, Vahid Azimi, Daniel J. Simon, Elizabeth Hardin
An Extensive Set Of Kinematic And Kinetic Data For Individuals With Intact Limbs And Transfemoral Prosthesis Users, Seyed Abolfazl Fakoorian, Arash Roshanineshat, Poya Khalaf, Vahid Azimi, Daniel J. Simon, Elizabeth Hardin
Electrical and Computer Engineering Faculty Publications
This paper introduces an extensive human motion data set for typical activities of daily living. These data are crucial for the design and control of prosthetic devices for transfemoral prosthesis users. This data set was collected from seven individuals, including five individuals with intact limbs and two transfemoral prosthesis users. These data include the following types of movements: (1) walking at three different speeds; (2) walking up and down a 5-degree ramp; (3) stepping up and down; (4) sitting down and standing up. We provide full-body marker trajectories and ground reaction forces (GRFs) as well as joint angles, joint velocities, …
Estimation Of Gait Kinematics And Kinetics From Inertial Sensor Data Using Optimal Control Of Musculoskeletal Models, Eva Dorschky, Marlies Nitschke, Ann-Kristin Seifer, Antonie J. Van Den Bogert, Bjoern M. Eskofier
Estimation Of Gait Kinematics And Kinetics From Inertial Sensor Data Using Optimal Control Of Musculoskeletal Models, Eva Dorschky, Marlies Nitschke, Ann-Kristin Seifer, Antonie J. Van Den Bogert, Bjoern M. Eskofier
Mechanical Engineering Faculty Publications
Inertial sensing enables field studies of human movement and ambulant assessment of patients. However, the challenge is to obtain a comprehensive analysis from low-quality data and sparse measurements. In this paper, we present a method to estimate gait kinematics and kinetics directly from raw inertial sensor data performing a single dynamic optimization. We formulated an optimal control problem to track accelerometer and gyroscope data with a planar musculoskeletal model. In addition, we minimized muscular effort to ensure a unique solution and to prevent the model from tracking noisy measurements too closely. For evaluation, we recorded data of ten subjects walking …
Design And Analysis Of Novel Actuation Mechanism With Controllable Stiffness, Erivelton Gualter Dos Santos, Hanz Richter
Design And Analysis Of Novel Actuation Mechanism With Controllable Stiffness, Erivelton Gualter Dos Santos, Hanz Richter
Mechanical Engineering Faculty Publications
Actuators intended for human–machine interaction systems are usually designed to be mechanically compliant. Conventional actuators are not suitable for this purpose due to typically high stiffness. Advanced powered prosthetic and orthotic devices can vary their stiffness during a motion cycle and are power-efficient. This paper proposes a novel actuator design that modulates stiffness by means of a flexible beam. A motorized drive system varies the active length of the cantilever beam, thus achieving stiffness modulation. New large deflection formulation for cantilever beams with rolling contact constraints is used to determine the moment produced by the actuator. To validate the proposed …
Design, Control, And Optimization Of Robots With Advanced Energy Regenerative Drive Systems, Poya Khalaf
Design, Control, And Optimization Of Robots With Advanced Energy Regenerative Drive Systems, Poya Khalaf
ETD Archive
We investigate the control and optimization of robots with ultracapacitor based regenerative drive systems. A subset of the robot joints are conventional, in the sense that external power is used for actuation. Other joints are energetically self-contained passive systems that use ultracapacitors for energy storage. An electrical interconnection known as the star configuration is considered for the regenerative drives that allows for direct electric energy redistribution among joints, and enables higher energy utilization efficiencies. A semi-active virtual control strategy is used to achieve control objectives. We find closed-form expressions for the optimal robot and actuator parameters (link lengths, gear ratios, …
Advanced Processing Of Nickel-Titanium-Graphite Based Metal Matrix Composites, Amit K. Patil
Advanced Processing Of Nickel-Titanium-Graphite Based Metal Matrix Composites, Amit K. Patil
ETD Archive
A new class of in situ titanium carbide (TiC)/graphite (C) reinforced nickel matrix composites with variation in composition particularly varying C/Ti ratio have been processed using two different processing techniques. Firstly, via mechanical alloying (MA) followed by spark plasma sintering (SPS), i.e. solid-state processing. Secondly, using Laser engineered net shaping (LENSTM) technique, i.e. metal additive manufacturing technique. Mechanical alloying has gained special attention as a powerful non-equilibrium process for fabricating amorphous and nanocrystalline materials, whereas spark plasma sintering is a unique technique for processing dense and near net shape bulk alloys with homogeneous microstructure. Laser engineered net shaping (LENSTM) is …
Robust Impedance Control Of A Four Degree Of Freedom Exercise Robot, Santino Joseph Bianco
Robust Impedance Control Of A Four Degree Of Freedom Exercise Robot, Santino Joseph Bianco
ETD Archive
The CSU 4OptimX exercise robot provides a platform for future research into advanced exercise and rehabilitation. The robot and its control system will autonomously modify reference trajectories and impedances on the basis of an optimization criterion and physiological feedback. To achieve this goal, a robust impedance control system with trajectory tracking must be implemented as the foundational control scheme. Two control laws will be compared, sliding mode and H-infinity control. The above robust control laws are combined with underlying impedance control laws to overcome uncertain plant model parameters and disturbance anomalies affecting the input signal. The sliding mode control law …
A Reticulation Of Skin-Applied Strain Sensors For Motion Capture, Christopher A. Schroeck
A Reticulation Of Skin-Applied Strain Sensors For Motion Capture, Christopher A. Schroeck
ETD Archive
The purpose of this research is to develop a system of motion capture based on skin-applied strain sensors. These elastic sensors are of interest because they can be applied to the body without restricting motion and are well suited to operate in more practical environments, such as sports fields, gymnasiums, and outdoor areas. This combination is currently not available in the field of motion capture. The current issues with strain sensor motion capture technology is the accurate is not sufficient for motion analysis and axial rotation monitoring of joints is not available. This project will build and test a sensor …
Metabolic Cost Calculations Of Gait Using Musculoskeletal Energy Models, A Comparison Study, Anne D. Koelewijn, Dieter Heinrich, Antonie J. Van Den Bogert
Metabolic Cost Calculations Of Gait Using Musculoskeletal Energy Models, A Comparison Study, Anne D. Koelewijn, Dieter Heinrich, Antonie J. Van Den Bogert
Mechanical Engineering Faculty Publications
This paper compares predictions of metabolic energy expenditure in gait using seven metabolic energy expenditure models to assess their correlation with experimental data. Ground reaction forces, marker data, and pulmonary gas exchange data were recorded for six walking trials at combinations of two speeds, 0.8 m/s and 1.3 m/s, and three inclines, -8% (downhill), level, and 8% (uphill). The metabolic cost, calculated with the metabolic energy models was compared to the metabolic cost from the pulmonary gas exchange rates. A repeated measures correlation showed that all models correlated well with experimental data, with correlations of at least 0.9. The model …
State Estimation For An Agonistic‐Antagonistic Muscle System, Thang Tien Nguyen, Holly Warner, Hung La, Hanieh Mohammadi, Daniel J. Simon, Hanz Richter
State Estimation For An Agonistic‐Antagonistic Muscle System, Thang Tien Nguyen, Holly Warner, Hung La, Hanieh Mohammadi, Daniel J. Simon, Hanz Richter
Electrical and Computer Engineering Faculty Publications
Research on assistive technology, rehabilitation, and prosthetics requires the understanding of human machine interaction, in which human muscular properties play a pivotal role. This paper studies a nonlinear agonistic‐antagonistic muscle system based on the Hill muscle model. To investigate the characteristics of the muscle model, the problem of estimating the state variables and activation signals of the dual muscle system is considered. In this work, parameter uncertainty and unknown inputs are taken into account for the estimation problem. Three observers are presented: a high gain observer, a sliding mode observer, and an adaptive sliding mode observer. Theoretical analysis shows the …
Opensim Versus Human Body Model: A Comparison Study For The Lower Limbs During Gait, Antoine Falisse, Sam Van Rossom, Johannes Gijsbers, Frans Steenbrink, Ben J. Van Basten, Ilse Jonkers, Antonie J. Van Den Bogert, Friedl De Groote
Opensim Versus Human Body Model: A Comparison Study For The Lower Limbs During Gait, Antoine Falisse, Sam Van Rossom, Johannes Gijsbers, Frans Steenbrink, Ben J. Van Basten, Ilse Jonkers, Antonie J. Van Den Bogert, Friedl De Groote
Mechanical Engineering Faculty Publications
Musculoskeletal modeling and simulations have become popular tools for analyzing human movements. However, end users are often not aware of underlying modeling and computational assumptions. This study investigates how these assumptions affect biomechanical gait analysis outcomes performed with Human Body Model and the OpenSim gait2392 model. The authors compared joint kinematics, kinetics, and muscle forces resulting from processing data from 7 healthy adults with both models. Although outcome variables had similar patterns, there were statistically significant differences in joint kinematics (maximal difference: 9.8 degrees {[}1.5 degrees] in sagittal plane hip rotation), kinetics (maximal difference: 0.36 {[}0.10] N.m/kg in sagittal plane …
Capturing The Competing Influence Of Thermal And Mechanical Loads On The Strain Of Turbine Blade Coatings Via High Energy X-Rays, Albert Manero, Kevin Knipe, Janine Wischek, Carla Meid, John Okasinski, Jonathan Almer, Anette M. Karlsson, Marion Bartsch, Seetha Raghavan
Capturing The Competing Influence Of Thermal And Mechanical Loads On The Strain Of Turbine Blade Coatings Via High Energy X-Rays, Albert Manero, Kevin Knipe, Janine Wischek, Carla Meid, John Okasinski, Jonathan Almer, Anette M. Karlsson, Marion Bartsch, Seetha Raghavan
Mechanical Engineering Faculty Publications
This paper presents findings of synchrotron diffraction measurements on tubular specimens with a thermal barrier coating (TBC) system applied by electron beam physical vapor deposition (EB-PVD), having a thermally grown oxide (TGO) layer due to aging in hot air. The diffraction measurements were in situ while applying a thermal cycle with high temperature holds at 1000 °C and varying internal air cooling mass flow and mechanical load. It was observed that, during high temperature holds at 1000 °C, the TGO strain approached zero if no mechanical load or internal cooling was applied. When applying a mechanical load, the TGO in-plane …
Compensation For Inertial And Gravity Effects In A Moving Force Platform, Sandra K. Hnat, Ben J.H. Van Basten, Antonie J. Van Den Bogert
Compensation For Inertial And Gravity Effects In A Moving Force Platform, Sandra K. Hnat, Ben J.H. Van Basten, Antonie J. Van Den Bogert
Mechanical Engineering Faculty Publications
Force plates for human movement analysis provide accurate measurements when mounted rigidly on an inertial reference frame. Large measurement errors occur, however, when the force plate is accelerated, or tilted relative to gravity. This prohibits the use of force plates in human perturbation studies with controlled surface movements, or in conditions where the foundation is moving or not sufficiently rigid. Here we present a linear model to predict the inertial and gravitational artifacts using accelerometer signals. The model is first calibrated with data collected from random movements of the unloaded system and then used to compensate for the errors in …
Optimal Mixed Tracking/Impedance Control With Application To Transfemoral Prostheses With Energy Regeneration, Gholamreza Khademi, Hanieh Mohammadi, Hanz Richter, Daniel J. Simon
Optimal Mixed Tracking/Impedance Control With Application To Transfemoral Prostheses With Energy Regeneration, Gholamreza Khademi, Hanieh Mohammadi, Hanz Richter, Daniel J. Simon
Mechanical Engineering Faculty Publications
We design an optimal passivitybased tracking/impedance control system for a robotic manipulator with energy regenerative electronics, where the manipulator has both actively and semi-actively controlled joints. The semi-active joints are driven by a regenerative actuator that includes an energy-storing element. Method: External forces can have a large influence on energy regeneration characteristics. Impedance control is used to impose a desired relationship between external forces and deviation from reference trajectories. Multi-objective optimization (MOO) is used to obtain optimal impedance parameters and control gains to compromise between the two conflicting objectives of trajectory tracking and energy regeneration. We solve the MOO problem …
Opty: Software For Trajectory Optimization And Parameter Identification Using Direct Collocation, Jason K. Moore, Antonie J. Van Den Bogert
Opty: Software For Trajectory Optimization And Parameter Identification Using Direct Collocation, Jason K. Moore, Antonie J. Van Den Bogert
Mechanical Engineering Faculty Publications
opty is a tool for describing and solving trajectory optimization and parameter identification problems based on symbolic descriptions of ordinary differential equations and differential algebraic equations that describe a dynamical system. The motivation for its development resides in the need to solve optimal control problems of biomechanical systems. The target audience is engineers and scientists interested in solving nonlinear optimal control and parameter identification problems with minimal computational overhead.
Advanced Manufacturing Of Titanium Alloys For Biomedical Applications, Nicholas C. Mavros
Advanced Manufacturing Of Titanium Alloys For Biomedical Applications, Nicholas C. Mavros
ETD Archive
In metallurgy, Titanium has been a staple for biomedical purposes. Its low toxicity and alloying versatility make it an attractive choice for medical applications. However, studies have shown the difference in elastic modulus between Titanium alloys (116 GPa) and human bone (40-60 GPa) contribute to long term issues with loose hardware fixation. Additionally, long term studies have shown elements such as Vanadium and Aluminum, which are commonly used in Ti-6Al-4V biomedical alloys, have been linked to neurodegenerative diseases like Alzheimers and Parkinsons. Alternative metals known to be less toxic are being explored as replacements for alloying elements in Titanium alloys. …
Spark Plasma Sintering Of Soft Magnetic Materials, Harnavdeep Kaur, Taban Larimian, Javier Esquivel
Spark Plasma Sintering Of Soft Magnetic Materials, Harnavdeep Kaur, Taban Larimian, Javier Esquivel
Undergraduate Research Posters 2018
Over the past 3 decades, iron-based soft magnetic alloys such as Finemet (Fe73.5Si13.5B9Nb3Cu1 (at%)) have attracted great interest due to their exceptional magnetic properties like high magnetization, low coercivity, and high curie temperature. However, the production of amorphous precursor requires very high cooling rates, and thus only wires, powders, and thin ribbons are achievable, yet these are not suitable in industrial applications where large volume of bulk magnetic components is required. Mechanical alloying (MA) has gained special attention as a powerful non-equilibrium process for fabricating amorphous and nanocrystalline materials, whereas spark plasma sintering (SPS) is a unique technique for processing …
Comparative Study Of The Microstructure And Mechanical Properties Of Mechanically Alloyed And Spark Plasma Sintered Alxcocrfeni (0≤X≤2)High Entropy Alloys, David Mikhail
Undergraduate Research Posters 2018
High entropy alloys are a new class of material systems that have promising potential in high temperature structural applications. Mechanical alloying (MA) has gained special attention as a powerful non-equilibrium process for fabricating amorphous and nanocrystalline materials, whereas spark plasma sintering (SPS) is a unique technique for processing dense and near net shape bulk alloys with homogenous microstructure. This research paper discusses novel mechanically alloyed followed by spark plasma sintering approach for assessing composition-microstructure-microhardness relationship in AlxCoCrFeNi (0≤x≤2) high entropy alloy as a candidate system. With increasing Al content, there was a gradual change from a fcc-based microstructure to a …
Human Activity Tracking And Recognition Using Kinect Sensor, Roanna Lun
Human Activity Tracking And Recognition Using Kinect Sensor, Roanna Lun
ETD Archive
The objective of this dissertation research is to use Kinect sensor, a motion sensing input device, to develop an integrated software system that can be used for tracking non-compliant activity postures of consented health-care workers for assisting the workers' compliance to best practices, allowing individualized gestures for privacy-aware user registration, movement recognition using rule-based algorithm, real-time feedback, and exercises data collection. The research work also includes developing a graphical user interface and data visualization program for illustrating statistical information for administrator, as well as utilizing cloud based database system used for data resource.
Non-Intrusive Optical Measurement Of Electron Temperature In Near Field Plume Of Hall Thruster, Peter J. Urban
Non-Intrusive Optical Measurement Of Electron Temperature In Near Field Plume Of Hall Thruster, Peter J. Urban
ETD Archive
Currently there is a large interest in the use of more efficient means of propulsion in long term missions due to the costs and difficulties associated with placing and maintaining the needed fuel for conventional chemical systems in orbit. Mass reduction of upper stages will return large returns due to the great reduction in required lower stage fuel. Due to these factors, alternatives are undergoing active research, though this paper is concerned with the area of electrical propulsion. Electric propulsion is broadly defined as propulsion where the energization of the exhaust occurs via application of electromagnetic fields as opposed to …
Neuromuscular Reflex Control For Prostheses And Exoskeletons, Sandra K. Hnat
Neuromuscular Reflex Control For Prostheses And Exoskeletons, Sandra K. Hnat
ETD Archive
Recent powered lower-limb prosthetic and orthotic (P/O) devices aim to restore legged mobility for persons with an amputation or spinal cord injury. Though various control strategies have been proposed for these devices, specifically finite-state impedance controllers, natural gait mechanics are not usually achieved. The goal of this project was to invent a biologically-inspired controller for powered P/O devices. We hypothesize that a more muscle-like actuation system, including spinal reflexes and vestibular feedback, can achieve able-bodied walking and also respond to outside perturbations. The outputs of the Virtual Muscle Reflex (VMR) controller are joint torque commands, sent to the electric motors …
Predictive Simulations Of Gait And Their Application In Prosthesis Design, Anne D. Koelewijin
Predictive Simulations Of Gait And Their Application In Prosthesis Design, Anne D. Koelewijin
ETD Archive
Predictive simulations predict human gait by solving a trajectory optimization problem by minimizing energy expenditure. These simulations could predict the effect of a prosthesis on gait before its use. This dissertation has four aims, to show the application of predictive simulations in prosthesis design and to improve the quality of predictive simulations. Aim 1 was to explain joint moment asymmetry in the knee and hip in gait of persons with a transtibial amputation (TTA gait). Predictive simulations showed that an asymmetric gait required less effort. However, a small effort increase yielded a gait with increased joint moment symmetry and reduced …
An Anisotropic Constitutive Model For Nuclear Grade Graphite, James Christopher
An Anisotropic Constitutive Model For Nuclear Grade Graphite, James Christopher
ETD Archive
Graphite material is used extensively in nuclear reactors however the material has a limited strain range for elastic behavior. This provides the motivation to derive a constitutive model that captures the inelastic deformations exhibited by this material. This dissertation first presents details of an isotropic constitutive model derived using continuum principles of engineering mechanics that accounts for different inelastic behavior in tension and compression. An inelastic dissipation function was developed using an integrity basis proposed by Green and Mkrtichian (1977) for the isotropic version of the model. This isotropic model was then extended to capture anisotropic stress-strain behavior using directional …
Bidirectionally Stretched Flow Of Jeffrey Liquid With Nanoparticles, Rosseland Radiation And Variable Thermal Conductivity, M. Archana, B. J. Gireesha, M. M. Rashidi, B. C. Prasannakumara, Rama S.R. Gorla
Bidirectionally Stretched Flow Of Jeffrey Liquid With Nanoparticles, Rosseland Radiation And Variable Thermal Conductivity, M. Archana, B. J. Gireesha, M. M. Rashidi, B. C. Prasannakumara, Rama S.R. Gorla
Mechanical Engineering Faculty Publications
Heat and mass transfer stretched flow of an incompressible, electrically conducting Jeffrey fluid has been studied numerically. Nanoparticles are suspended in the base fluid and it has many applications such as cooling of engines, thermal absorption systems, lubricants fuel cell, nanodrug delivery system and so on. Temperature dependent variable thermal conductivity with Rosseland approximation is taken into account and suction effect is employed in the boundary conditions. The governing partial differential equations are first transformed into set of ordinary differential equations using selected similarity transformations, which are then solved numerically using Runge-Kutta-Felhberg fourth-fifth order method along with shooting technique. The …
Optimal Design And Control Of An Electromechanical Transfemoral Prosthesis With Energy Regeneration, Farbod Rohani, Hanz Richter, Antonie J. Van Den Bogert
Optimal Design And Control Of An Electromechanical Transfemoral Prosthesis With Energy Regeneration, Farbod Rohani, Hanz Richter, Antonie J. Van Den Bogert
Mechanical Engineering Faculty Publications
In this paper, we present the design of an electromechanical above-knee active prosthesis with energy storage and regeneration. The system consists of geared knee and ankle motors, parallel springs for each motor, an ultracapacitor, and controllable four-quadrant power converters. The goal is to maximize the performance of the system by finding optimal controls and design parameters. A model of the system dynamics was developed, and used to solve a combined trajectory and design optimization problem. The objectives of the optimization were to minimize tracking error relative to human joint motions, as well as energy use. The optimization problem was solved …
Forming A Metal Matrix Nanocomposite (Mmnc) With Fully Dispersed And Deagglomerated Multiwalled Carbon Nanotubes (Mwcnts), Mahesh Kumar Pallikonda
Forming A Metal Matrix Nanocomposite (Mmnc) With Fully Dispersed And Deagglomerated Multiwalled Carbon Nanotubes (Mwcnts), Mahesh Kumar Pallikonda
ETD Archive
Carbon Nanotubes (CNTs) with their exceptional properties will facilitate the Metal matrix composites (MMC) to exhibit good mechanical properties, thermal and electrical conductivities, corrosion resistance, etc. The critical factor that holds the development of the Metal matrix Nanocomposites (MMNC) by using CNTs is the tendency of CNTs to form clusters (agglomerations) due to their high Van der Waals attractions. Due to this factor, low density and other properties of the CNTs, there has been a delay in harnessing their ultimate potential.
Existing literature in contemporary times from the works of few researches in Nanocomposites shows the prevalence of using surfactants …