Mechanical Engineering Commons^™

Assessing Plastically Dissipated Energy As A Condition For Fatigue Crack Growth, D. Cojocaru, Anette M. Karlsson

Mechanical Engineering Faculty Publications

The suitability of using a proposed condition for simulating cyclic crack propagation in a numerical scheme is qualitatively investigated, employing the finite element method. The propagation criterion is based on a condition that relates the plastically dissipated energy to a critical value. In the finite element simulation scheme, the crack is allowed to propagate when the criterion is satisfied, and the crack propagates until the condition is no longer fulfilled. Experimentally, it is well established that a negative load ratio increases the crack propagation rate, whereas a tensile overload tends to decrease the crack propagation rate. By simulating these load …

Phase Tunable Holographic Fabrication For Three-Dimensional Photonic Crystal Templates By Using A Single Optical Element, Di Xu, Kevin P. Chen, Ahmad Harb, Daniel Rodriguez, Karen Lozano, Yuankun Lin

Mechanical Engineering Faculty Publications

This paper demonstrates a phase tunable holographic fabrication of three-dimensional photonic lattice structures using a single optical element. A top-cut four-side prism is employed to generate five-beam three-dimensional interference patterns. A silica glass slide is inserted into the optical path to adjust the phase of one interfering beam relative to other four beams. The phase control of the interfering laser beam renders the lattice of the interference pattern from a face-center tetragonal symmetry into a high contrast, interconnecting diamondlike symmetry. This method provides a flexible approach to fabricating three-dimensional photonic lattices with improved photonic band structures.

A Microfabricated Segmented-Involute-Foil Regenerator For Enhancing Reliability And Performance Of Stirling Engines: Phase Iii Final Report For The Radioisotope Power Conversion Technology Nra Contract Nas3-03124, Mounir B. Ibrahim, David Gedeon, Gary Wood, Jeffrey Mclean

Mechanical Engineering Faculty Publications

Under Phase III of NASA Research Announcement contract NAS3-03124, a prototype nickel segmented-involute-foil regenerator was microfabricated and tested in a Sunpower Frequency-Test-Bed (FTB) Stirling convertor. The team for this effort consisted of Cleveland State University, Gedeon Associates, Sunpower Inc. and International Mezzo Technologies. Testing in the FTB convertor produced about the same efficiency as testing with the original random-fiber regenerator. But the high thermal conductivity of the prototype nickel regenerator was responsible for a significant performance degradation. An efficiency improvement (by a 1.04 factor, according to computer predictions) could have been achieved if the regenerator was made from a low-conductivity …

Mechanics-Based Model For Non-Affine Swelling In Perfluorosulfonic Acid (Pfsa) Membranes, Ahmet Kusoglu, Michael H. Santare, Anette M. Karlsson

Mechanical Engineering Faculty Publications

A mechanics-based model is developed to predict the swelling pressure in perfluorosulfonic acid (PFSA) ionomer membranes during water uptake. The PFSA membrane is represented as a two-phase system, where the water-filled hydrophilic domains are dispersed throughout the hydrophobic polymer matrix. Two representative volume elements (RVEs) are used to represent the nanostructure: (i) a spherical RVE with a spherical hydrophilic domain at the center, and (ii) a cylindrical RVE with a cylindrical hydrophilic domain. The model starts with the non-affine swelling behavior of the membrane and interprets this as a structural reorganization of the RVEs to characterize the microscopic deformation. Swelling …

Investigation Of The Electromagnetic Interference Shielding Of Titanium Carbide Coated Nanoreinforced Liquid Crystalline Polymer, Karen Lozano, Lesly Espinoza, K. Hernandez, Ananta R. Adhikari, Gangaram Radhakrishnan, P. M. Adams

Mechanical Engineering Faculty Publications

The development and analysis of electrical and electromagnetic interference shielding effectiveness of titanium carbide (TiC)-coated carbon nanofiber (CNF) reinforced liquid crystalline polymer composites are presented. The studied samples consisted of different weight percentages (5, 10, and 15 wt %) of CNFs distributed and dispersed homogeneously within the polymeric matrix. A titanium carbide layer was deposited using pulsed laser deposition, and was conducted at room temperature, which eliminated possible thermal degradation of the polymer matrix. The effect of the thickness of the TiC layer on the electrical properties of the polymeric composites was analyzed. A synergistic behavior between the TiC coating …

A Real-Time, 3-D Musculoskeletal Model For Dynamic Simulation Of Arm Movements, Edward K. Chadwick, Dimitra Blana, Antonie J. Van Den Bogert, Robert F. Kirsch

Mechanical Engineering Faculty Publications

Neuroprostheses can be used to restore movement of the upper limb in individuals with high-level spinal cord injury. Development and evaluation of command and control schemes for such devices typically require real-time, ldquopatient-in-the-looprdquo experimentation. A real-time, 3-D, musculoskeletal model of the upper limb has been developed for use in a simulation environment to allow such testing to be carried out noninvasively. The model provides real-time feedback of human arm dynamics that can be displayed to the user in a virtual reality environment. The model has a 3-DOF glenohumeral joint as well as elbow flexion/extension and pronation/supination and contains 22 muscles …

On Stresses Induced In A Thermal Barrier Coating Due To Indentation Testing, Jin Yan, Anette M. Karlsson, Marion Bartsch, Xi Chen

Mechanical Engineering Faculty Publications

Instrumented indentation has been suggested as a method to determine interfacial fracture toughness of thermal barrier coatings. However, in a previous experimental study we showed that the results are ambiguous. In this work, we investigate the experimental results by numerical simulations incorporating the material microstructure. In the numerical simulations, based on finite element analyses, the stress fields that are associated with the loading and unloading of the indenter are investigated. By comparing these stress fields to the damage observed in the experimental study, including crack path and interfacial delaminations, we explain key findings from the experimental observations. Our results suggest …

Stress-Strain Behavior Of Perfluorosulfonic Acid Membranes At Various Temperatures And Humidities: Experiments And Phenomenological Modeling, Ahmet Kusoglu, Yaliang Tang, Michael Santare, Anette M. Karlsson, Simon Cleghorn, William B. Johnson

Mechanical Engineering Faculty Publications

The constitutive response of perfluorinated sulfonic acid (PFSA) membranes based on tensile testing is investigated, and a phenomenological constitutive model for the elastoplastic flow behavior as a function of temperature and humidity is proposed. To this end, the G'Sell–Jonas (1979, “Determination of the Plastic Behavior of Solid Polymers at Constant True Strain Rate,” J. Mater. Sci., 14, pp. 583–591) constitutive model for semicrystalline polymers is extended by incorporating, in addition to temperature, relationships between the material constants of this model and the measured relative humidity. By matching the proposed constitutive model to the experimental stress-strain data, useful material constants …

Extended Kalman Filter Implementation For The Khepera Ii Mobile Robot, Thomas J. Otahal, Herbert G. Tanner

Mechanical Engineering Faculty Publications

The accurate estimation of robot position and orientation in real-time is one of the fundamental challenges in mobile robotics. The Extended Kalman Filter is a nonlinear real-time recursive time domain filter that combines available sensor data to produce an accurate estimate of state, and has been successfully applied to the localization problem in mobile robotics and aircraft navigation. This report describes an Extended Kalman Filter implementa- tion for the Khepera II mobile robotics platform that seeks to produce accurate localization estimates in real-time using wheel odometry data, IR sensor range data, and compass heading data.

Analysis Of Flux-Base Fins For Estimation Of Heat Transfer Coefficient, Kevin D. Cole, Constantine Tarawneh, Brent M. Wilson

Mechanical Engineering Faculty Publications

Exact solutions are given for the transient temperature in flux-base fins with the method of Green’s functions (GF) in the form of infinite series for three different tip conditions. The speed of convergence is improved by replacing the steady part by a closed-form steady solution. For the insulated-tip case, a quasi-steady solution is presented. Numerical values are presented and the conditions under which the quasi-steady solution is accurate are determined. An experimental example is given for estimation of the heat transfer coefficient (HTC) on a non-rotating roller bearing, in which the outer bearing race is treated as a transient fin.

Diamond And Related Nanomaterials For Mems/Nems Applications, Rakesh K. Joshi, Ashok Kumar

Mechanical Engineering Faculty Publications

No abstract provided.

Application Of The Actor-Critic Architecture To Functional Electrical Stimulation Control Of A Human Arm, Philip 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 the actor-critic architecture, with neural networks for the both the actor and the critic, as a controller that can adapt to these changing dynamics of a human arm. Development and tests were done in simulation using a planar arm model and Hill-based muscle dynamics. We begin by training it using a Proportional Derivative (PD) controller as a supervisor. We then make clinically relevant changes to the dynamics of …

Concurrent Simulation Of Neuromuscular Control And Tissue Deformation Is Possible By Adaptive Surrogate Modeling, Jason P. Halloran, Ahmet Erdemir, Antonie J. Van Den Bogert

Mechanical Engineering Faculty Publications

No abstract provided.

Adaptive Surrogate Modeling For Efficient Coupling Of Musculoskeletal Control And Tissue Deformation Models, Jason P. Halloran, Ahmet Erdemir, Antonie J. Van Den Bogert

Mechanical Engineering Faculty Publications

Background

Finite element (FE) modeling and multibody dynamics have traditionally been applied separately to the domains of tissue mechanics and musculoskeletal movements, respectively. Simultaneous simulation of both domains is needed when interactions between tissue and movement are of interest, but this has remained largely impractical due to high computational cost.

Method of Approach

Here we present a method for concurrent simulation of tissue and movement, in which state of the art methods are used in each domain, and communication occurs via a surrogate modeling system based on locally weighted regression. The surrogate model only performs FE simulations when regression from …

Multiresolution Wavelet Analysis Of The Dynamics Of A Cracked Rotor, Jerzy T. Sawicki, Asok K. Sen, Grzegorz Litak

Mechanical Engineering Faculty Publications

We examine the dynamics of a healthy rotor and a rotor with a transverse crack, which opens and closes due to its self weight. Using discrete wavelet transform, we perform a multiresolution analysis of the measured vibration signal from each of these rotors. In particular, the measured vibration signal is decomposed into eight frequency bands, and the rms amplitude values of the healthy and cracked rotors are compared in the three lowest-frequency bands. The results indicate that the rms vibration amplitudes for the cracked rotor are larger than those of the healthy rotor in each of these three frequency bands. …

An Object-Oriented Approach For Modeling And Simulation Of Crack Growth In Cyclically Loaded Structures, D. Cojocaru, Anette M. Karlsson

Mechanical Engineering Faculty Publications

We present an object-oriented modeling frame for simulating crack propagation due to cyclic loadings. Central to the approach is that the crack propagates when a user-defined propagation criterion is fulfilled, i.e., the crack propagation rate is not prescribed but predicted. The approach utilizes the commercial finite element software package ABAQUS and its associated Python based scripting interface. The crack propagation is simulated by a generalized node release technique. If the propagation criteria are satisfied in the end of a cycle, the crack is allowed to propagate. The incremental crack growth is inferred from an iterative investigation of the propagation criteria. …

Experiments And Models For The Thermal Response Of Railroad Tapered-Roller Bearings, Constantine Tarawneh, Kevin D. Cole, Brent Wilson, Fadi Alnaimat

Mechanical Engineering Faculty Publications

The need to understand and quantify the heat transfer paths within tapered-roller bearings is of great importance in the railroad industry since bearing cup temperature measurement is the primary tool utilized in the removal of distressed bearings from service. Experiments were performed to acquire temperature histories at several locations on a stationary bearing subjected to heat sources imbedded in two rollers. The experimental results were compared to zero- and first-order thermal models to estimate overall heat transfer coefficients from the bearing. The results presented here can be used to explain some of the mechanisms that lead to overheating of tapered-roller …

Holographic Fabrication Of Photonic Crystals Using Multidimensional Phase Masks, Yuankun Lin, Ahmad Harb, Daniel Rodriguez, Karen Lozano, Di Xu, K. P. Chen

Mechanical Engineering Faculty Publications

This paper reports the experimental approaches to the fabrication of two-layer integrated phase masks and the fabrication of photonic crystal templates using the phase mask based on holographic lithography technique. The photonic crystal template is formed by exposing photoresist mixtures to five-beam interference patterns generated through the phase mask. The fabricated phase mask consists of two layers of orthogonally oriented gratings produced in a liquid crystal and photoresist mixture. A polymerization-induced phase separation preserves the grating structure during the exposure. The vertical spatial separation between two layers of gratings produces a phase difference among diffracted laser beams, which enables the …

Micromechanics Model Based On The Nanostructure Of Pfsa Membranes, Ahmet Kusoglu, Michael H. Santare, Anette M. Karlsson, William B. Johnson, Simon Cleghorn

Mechanical Engineering Faculty Publications

A micromechanics model is developed to predict Young’s modulus of perfluorosulfonic acid (PFSA) membranes at various temperatures and water contents. The morphology of PFSA membranes is characterized by a two-phase structure, where hydrophilic clusters expand to hold water molecules during swelling, whereas the hydrophobic polymer network maintains the structural stability. A representative volume element (RVE) is proposed based on the descriptions for the nanostructure of PFSA membranes available in the literature. On the basis of mechanics model, we estimate Young’s modulus in tension of PFSA membranes as a function of water volume fraction for various temperatures. The results show that …

Image Analyses Of Two Crustacean Exoskeletons And Implications Of The Exoskeletal Microstructure On The Mechanical Behavior, Liang Cheng, Liyun Wang, Anette M. Karlsson

Mechanical Engineering Faculty Publications

The microstructures of exoskeletons from Homarus americanus (American lobster) and Callinectes sapidus (Atlantic blue crab) were investigated to elucidate the mechanical behavior of such biological composites. Image analyses of the cross-sectioned exoskeletons showed that the two species each have three well-defined regions across the cuticle thickness where the two innermost regions (exocuticle and endocuticle) are load bearing. These regions consist of mineralized chitin fibers aligned in layers, where a gradual rotation of the fiber orientation of the layers results in repeating stacks. The exocuticle and endocuticle of the two species have similar morphology, but different thicknesses, number of layers, and …

Closure To “Discussion: ‘On The Reference Length And Mode Mixity For A Bimaterial Interface’ ” (2008, Asme J. Eng. Mater. Technol., 130, P. 045501), Anette M. Karlsson

Mechanical Engineering Faculty Publications

No abstract provided.

On Cracks And Delaminations Of Thermal Barrier Coatings Due To Indentation Testing: Experimental Investigations, Jin Yan, Thorsten Leist, Marion Bartsch, Anette M. Karlsson

Mechanical Engineering Faculty Publications

Rockwell indentation testing as a method of establishing the interfacial fracture toughness of thermal barrier coatings is investigated. To this end, indentation tests have been systematically performed on coatings with yttria-stabilized zirconia top coat deposited by electron beam physical vapor deposition. Specimens in “as-coated” condition and after heat treatment in air have been studied. Unexpectedly, indentation of the heat-treated samples resulted in smaller delaminations than the as-coated samples, suggesting an increase in fracture toughness for coatings subjected to elevated temperatures. Careful image analyses of the cross-section of the indented area show that the ceramic top coat undergoes a complex damage …

Investigating Isolated Neuromuscular Control Contributions To Non-Contact Anterior Cruciate Ligament Injury Risk Via Computer Simulation Methods, Scott G. Mclean, Xuemei Huang, Antonie J. Van Den Bogert

Mechanical Engineering Faculty Publications

Background

Despite the ongoing evolution of anterior cruciate ligament injury prevention methods, injury rates and the associated sex-disparity remain. Strategies capable of successfully countering key control parameters existent within the injury mechanism thus remain elusive. Forward dynamics model simulations afford an expedited means to study realistic injury causing scenarios, while controlling all facets of the movement control strategy. Utilizing these methods, the current study examined the potential for perturbations in key initial contact neuromuscular parameters to injure the anterior cruciate ligament during the stance phase of sidestep cutting maneuvers.

Methods

Controlled experiments were performed on optimized and validated subject-specific forward …

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 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 …

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 …

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 …

Fabrication And Characterization Of Zno Nanowire Arrays With An Investigation Into Electrochemical Sensing Capabilities, Jessica Weber, Sathyaharish Jeedigunta, Ashok Kumar

Mechanical Engineering Faculty Publications

ZnO nanowire arrays were grown on a Si (100) substrate using the vapor-liquid-solid (VLS) method. ZnO nanowires were characterized by XRD, SEM, bright field TEM, and EDS. They were found to have a preferential orientation along the -axis. The as-prepared sample was functionalized with glucose oxidase by physical adsorption. FTIR was taken before and after functionalization to verify the presence of the attached enzyme. Electrochemical measurements were performed on the nanowire array by differential pulse voltammetry in the range of -0.6 to 0.4 V. The nanoarray sensor displayed high sensitivity to glucose in the range of 1.0 x 10^{-4 …}

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 …

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.