Mechanical Engineering Commons^™

Bioengineering Cartilage Growth, Maturation, And Form, Gregory M. Williams, Stephen M. Klisch, Robert L. Sah

Mechanical Engineering

Cartilage of articular joints grows and matures to achieve characteristic sizes, forms, and functional properties. Through these processes, the tissue not only serves as a template for bone growth but also yields mature articular cartilage providing joints with a low-friction, wear-resistant bearing material. The study of cartilage growth and maturation is a focus of both cartilage biologists and bioengineers with one goal of trying to create biologic tissue substitutes for the repair of damaged joints. Experimental approaches both in vivo and in vitro are being used to better understand the mechanisms and regulation of growth and maturation processes. This knowledge …

Nonlinear Contact Analysis Of Gear Teeth For Malfunction Diagnostics, D. Kong, J. M. Meagher, C. Xu, X. Wu, Y. Wu

Mechanical Engineering

Gearboxes sustain a variety of faults such as broken-shafts, eroded, broken, or missing teeth, and even broken-cases. Casing mounted accelerometers can detect fault patterns but the signals are complicated and difficult to interpret. This study considers the tooth loading of ideal gears and gears with defects. A large industrial gearbox used in a 12m³ electric mining shovel is modeled. The nonlinear contact mechanics is analyzed to predict the bearing supporting force variation vs. the gear tooth loading after a 3-D CAD model of the gearbox is transferred into multi-body dynamics software. The contact mechanics model of the meshing teeth …

Cartilage Growth And Remodeling: Modulation Of Balance Between Proteoglycan And Collagen Network In Vitro With Β-Aminopropionitrile, Anna Asanbaeva, Koichi Masuda, Eugene J-M.A. Thonar, Stephen M. Klisch, Robert L. Sah

Mechanical Engineering

Objective

To examine the effect of β-aminopropionitrile (BAPN), an inhibitor of lysyl oxidase, on growth and remodeling of immature articular cartilage in vitro.

Design

Immature bovine articular cartilage explants from the superficial and middle layers were cultured for 13 days in serum-containing medium with or without BAPN. Variations in tissue size, accumulation of proteoglycan and collagen (COL), and tensile mechanical properties were assessed.

Results

The inclusion of serum resulted in expansive tissue growth, stimulation of proteoglycan and COL deposition, and a diminution of tensile integrity. Supplementation of medium with BAPN accentuated this phenotype in terms of a further increase in …

Cal Poly Wind Power Research Center, Patrick Lemieux, John Ridgely

Mechanical Engineering

The Wind Power Research Center is being created at California State Polytechnic University in San Luis Obispo, California. This center brings together faculty, undergraduate and graduate students, and industry partners to conduct applied research and education in support of the wind power industry. Particular emphasis is given to research which serves the needs of manufacturers of smaller wind turbines, and to educating engineers who are well trained to work in all segments of the wind power industry.

A Two-Disk Extended Jeffcott Rotor Model Distinguishing A Shaft Crack From Other Rotating Asymmetries, Xi Wu, Jim Meagher

Mechanical Engineering

A mathematical model of a cracked rotor and an asymmetric rotor with two disks representing a turbine and a generator is utilized to study the vibrations due to imbalance and side load. Nonlinearities typically related with a “breathing” crack are included using a Mayes steering function. Numerical simulations demonstrate how the variations of rotor parameters affect the vibration response and the effect of coupling between torsional and lateral modes. Bode, spectrum, and orbit plots are used to show the differences between the vibration signatures associated with cracked shafts versus asymmetric shafts. Results show how nonlinear lateral-torsional coupling shifts the resonance …

Response Of A Warped Flexible Rotor With A Fluid Bearing, Jim Meagher, Xi Wu, Chris Lencioni

Mechanical Engineering

A two-complex-degrees-of-freedom model is developed and compared to experimental data for various amounts of rotor bow and its orientation to mass imbalance of the rotor. The equation of motion is developed by adding constant forces that rotate with the rotor to a Bently-Muszynska two-mode isotropic rotor model with a plane journal bearing. Diagnostic information discernable from probes at the bearing is explored and compared to midspan response, where previous research has concentrated. The model presented also extends earlier work by representing the effect of a nonrigid bearing. Good agreement between the analytical model and experiment demonstrates that the analysis presented …

Undergraduate Research: Experiences From A Three-Year Project, Peter Schuster, Charles Birdsong

Mechanical Engineering

There are significant benefits of research for the involved undergraduate student. These include exposure to advanced topics, introduction to research methods, and direct interaction with faculty and other students. Faculty and institutions benefit as well by the increased interaction with students – fresh eyes in research projects, more energized research groups, and more engaged alumni. However, there are some challenges in designing a research program to work primarily with undergraduates. These include the students’ lack of exposure to advanced topics, short tenure on the project, and potentially lower commitment to the results. There are a number of ways to address …

A Pre-Crash Simulator To Evaluate Vehicle Collision Prediction Algorithms, Dana Desrosiers, Charles Birdsong, Peter Schuster

Mechanical Engineering

This paper describes a software simulator for pre-crash collision predictions. The simulator is a surrogate test bed for evaluating the performance of proposed pre-crash algorithms. It reads data from a file, transfers distance and angular position of a target to a test algorithm, and then records the algorithm’s predictions. To illustrate the simulator functionality, a simplified test algorithm is also described. This algorithm predicts collision risks based on assumptions about the size and acceleration of a target object, and the turning and braking limits of the host vehicle. The test algorithm is shown to be effective for cases where both …

Design Integrated In The Mechanical Engineering Curriculum: Assessment Of The Engineering Clinics, Jennifer Kadlowec, Krishnan Bhatia, Tirupathi R. Chandrupatla, John C. Chen, Eric Constans, Harriet Hartman, Anthony J. Marchese, Paris Von Lockette, Hong Zhang

Mechanical Engineering

At Rowan University, design has been infused into the curriculum through an eight-semester course sequence called the Engineering Clinics. Through this experience, students learn the art and science of design in a multidisciplinary team environment and hone their design skills throughout their 4-year career. This paper describes the objectives of the clinics, types of projects, and how the clinics complement traditional core courses in the curriculum. Impacts and benefits of the clinics on students and faculty are discussed, including retention and graduate study rates comparing Rowan University mechanical engineering students to their peers nationally. An assessment of the clinics is …

Thermal Fatigue Test Apparatus For Large Superconducting Coils, J.T. Kephart, B.K. Fitzpatrick, John Chen, J. Lopez, M. Miller, L. Wong, M. Zimmerman, J. Kostic, C. Rakus

Mechanical Engineering

The United States Navy has a continued interest in the development of High Temperature Superconductivity (HTS) to provide power dense, efficient propulsion and electrical power generation. These machines have large HTS rotor coils that will undergo many thermal cycles during the life of the ship. Thermal fatigue tests for large coils are necessary to understand any degradation and life issues that could arise. The Naval Surface Warfare Center Carderock Division (NSWCCD) has sponsored Rowan University to design and build a device that will assist in the thermal fatigue testing of a superconducting coil. It was designed to be autonomous with …

Articular Cartilage Mechanical And Biochemical Property Relations Before And After In Vitro Growth, Timothy Ficklin, Gregory Thomas, James C. Barthel, Anna Asanbaeva, Eugene J. Thonar, Koichi Masuda, Albert C. Chen, Robert L. Sah, Andrew Davol, Stephen M. Klisch

Mechanical Engineering

The aim of this study was to design in vitro growth protocols that can comprehensively quantify articular cartilage structure–function relations via measurement of mechanical and biochemical properties. Newborn bovine patellofemoral groove articular cartilage explants were tested sequentially in confined compression (CC), unconfined compression (UCC), and torsional shear before (D0, i.e. day zero) and after (D14, i.e. day 14) unstimulated in vitro growth. The contents of collagen (COL), collagen-specific pyridinoline (PYR) crosslinks, glycosaminoglycan, and DNA significantly decreased during in vitro growth; consequently, a wide range of biochemical properties existed for investigating structure–function relations when pooling the D0 and D14 groups. All …

Developing A Matlab/Simulink Rtwt Based Hydraulic Servo Control Design Experiment, Charles Birdsong

Mechanical Engineering

While one of the stated goals of the Mechanical Engineering Controls course is to develop the tools to design a controller, previous lab experiences did not include an experimental exercise in controller design. This was primarily due to the difficulty in implementing a controller that is robust and flexible enough to accommodate different student designs within the short time constraints of a three hour lab period. This paper describes an effort to use the Mathworks Real Time Windows Target to implement student controller designs on real hardware in a lab setting. Students use experimental data and a physically based model …

Application Of Transformative Learning Theory In Engineering Education, John Chen

Mechanical Engineering

The goal of this work-in-progress is to improve student engagement and learning in courses that form the core of a discipline. Such gateway courses represent critical milestones in a student's academic career and have a strong influence on his or her attitude and future success in engineering. We contend that students who struggle in gateway courses do so because they are having difficulty with conceptual transformation, and this project aims to facilitate this change through the ideas advocated within Transformative Learning Theory. The essential elements of this project include the integration of information technologies, provision of rapid feedback to students …

Crack Growth Induced By Sonic Ir Inspection, John C. Chen, Jacob Kephart, Kyle Lick, William T. Riddell

Mechanical Engineering

We have developed an experiment to study the propagation of laboratory-synthesized fatigue cracks under various controlled conditions during Sonic IR inspection. The experiment provides for good repeatability in testing. The parameters of interest include the initial crack length, load history (stress intensity and load ratio) during crack generation, geometry of the crack, material and also the various conditions involving the ultrasonic excitation source. In general, we find that under typical sonic IR inspection conditions, the initial crack will propagate under sonic IR testing. The crack growth after each inspection event varies and exhibits a distribution in length of propagation. The …

Development Of A Biofidelic 'Legform' Impact Test Device, John Davis, Peter Schuster

Mechanical Engineering

Current EuroNCAP test specifications attempt to predict pedestrian lower limb injury in a lateral impact with a rigid legform test device developed by the UK's TRL (Transportation Research Lab). Research shows that the measurements taken from this device (knee bending angle, knee shear, and upper tibia acceleration) do not necessarily correspond to accurate injury prediction. Recent research suggests that the primary improvement to the current test device would be a flexible legform, or one that has more biofidelity (i.e., simulates actual human lower limb response).

The work presented in this paper first reviews current legforms developed for pedestrian impact testing, …

Investigation Of Coupled Lateral And Torsional Vibrations Of A Cracked Rotor Under Radial Load, Xi Mu, Jim Meagher, Clinton Judd

Mechanical Engineering

A practical cracked rotor model with two disks representing a turbine and generator is studied using a four degree of freedom model; two transverse displacements and two torsional angular displacements. The differential equations of a rotor with a crack, unbalance, and constant radial force are first derived in detail using energy principles. The nonlinearities related with a “breathing” crack are incorporated, which distinguishes this paper from others studying stiffness anisotropy of a rotor with a similar rotor configuration. Through numerical simulations, this paper demonstrates the lateral-torsional coupling that occurs with a shaft crack and predicts torsional critical speed frequencies at …

Response Of A Warped Flexible Rotor With A Fluid Bearing, Jim Meagher, Xi Wu, Chris Lencioni

Mechanical Engineering

A two complex degrees of freedom model is developed and compared to experimental data for various amounts of rotor bow and its orientation to mass imbalance of the rotor. The equation of motion is developed by adding constant forces that rotate with the rotor to a Bently-Muszynska two-mode isotropic rotor model with a plane journal bearing. Diagnostic information discernable from probes at the bearing is emphasized and compared to midspan response where previous research has concentrated. Good agreement between the analytical model and experiment demonstrate that the analysis presented can be useful to diagnose and balance residual shaft bow from …

Using Underwater Remotely Operated Vehicles As An Engineering Education Tool, Hong Zhang, John Chen, Eric Constans

Mechanical Engineering

Starting in 2004, the Department of Mechanical Engineering at Rowan University introduced a new tool into its program: Remotely Operated Vehicles (ROVs). The tool is used at different aspects ofeducation. As a coursework project, graduating ME seniors researched, designed, built, competed and reported with underwater ROVs to assess their design skills before heading out to start their careers. It tests a wide range of engineering background in one single project and gauges the soft skills such as teamwork, self-learning, communication and evaluation. As a student research project, a multidisciplinary student team developed a robotic field ROV to help biological scientists …

Integrating Design Throughout The Mechanical Engineering Curriculum: A Focus On The Engineering Clinics, Krishan Bhatia, Tirupathi R. Chandrupatla, John C. Chen, Eric Constans, Jennifer A. Kadlowec, Anthony J. Marchese, Paris Von Lockette, Hong Zhang

Mechanical Engineering

At Rowan University, we have infused design into the curriculum through an eight-semester course sequence called the Engineering Clinic. Through this experience students learn the art and science of design in a multidisciplinary team environment. While many engineering programs currently include a Capstone Design course taken near the end of the college career to meet the design needs, Engineering Clinic at Rowan allows students to hone their design skills throughout their four-year career. This paper will describe in further detail the objectives and execution of each year in the design sequence, types of projects and how the Clinics complement traditional …

Student Competitions - The Benefits And Challenges, Peter Schuster, Andrew Davol, Joseph Mello

Mechanical Engineering

Intercollegiate design competitions are a popular means to engage students in design activities that extend beyond the curriculum. When students gather around a project in their spare time and use their classroom skills to design, build, and test a product for an intercollegiate competition, something amazing happens: They develop a passion for engineering. This paper discusses the key benefits to engineering undergraduate students that flow from involvement in a team design competition. Advisor involvement plays a key role in both project success and student learning throughout the process. Different approaches to advising student competition teams are compared. Specific examples are …

Research In The Undergraduate Environment, Charles Birdsong, Peter Schuster

Mechanical Engineering

The benefits of research experiences for undergraduates are significant. For many faculty, these were the experiences that convinced us to pursue further education and a career in academia. However, performing research at an undergraduate institution carries with it certain challenges. In traditional research institutions, doctoral students perform most of the research activities, led by the faculty. These students have completed at least their undergraduate courses and can be expected to remain on the research team for four to six years. In contrast, at an undergraduate institution students may start in the group with only one or two engineering courses completed, …

A Bimodular Theory For Finite Deformations: Comparison Of Orthotropic Second-Order And Exponential Stress Constitutive Equations For Articular Cartilage, Stephen M. Klisch

Mechanical Engineering

Cartilaginous tissues, such as articular cartilage and the annulus fibrosus, exhibit orthotropic behavior with highly asymmetric tensile–compressive responses. Due to this complex behavior, it is difficult to develop accurate stress constitutive equations that are valid for finite deformations. Therefore, we have developed a bimodular theory for finite deformations of elastic materials that allows the mechanical properties of the tissue to differ in tension and compression. In this paper, we derive an orthotropic stress constitutive equation that is second-order in terms of the Biot strain tensor as an alternative to traditional exponential type equations. Several reduced forms of the bimodular second-order …

Current Trends In Bumper Design For Pedestrian Impact, Peter J. Schuster

Mechanical Engineering

Worldwide, the pace of development in pedestrian countermeasures is increasing rapidly. To better understand the state of the art in bumper design for pedestrian impact, a survey of literature and patents has been performed. Two general approaches to reducing the severity of pedestrian lower limb impacts were identified: (a) Provide cushioning and support of the lower limb with a bumper and a new lower stiffener, or (b) Use the bumper as a platform for impact sensors and exterior airbags. This study focused on the first approach. Excluding bumper sensors, airbags, and non-design-related articles, a total of 130 relevant technical articles …

An Investigation On The Importance Of Material Anisotropy In Finite-Element Modeling Of The Human Femur, Ryan Krone, Peter Schuster

Mechanical Engineering

Detailed finite element modeling of the human body offers a potential major enhancement to the prediction of injury risk during vehicle impacts. Currently, vehicle crash safety countermeasure development is based on a combination of testing with established anthropomorphic test devices (i.e., ATD or dummy) and a mixture of multi-body (dummy) and finite element (vehicle) modeling. If a relatively simple finite element model can be developed to capture additional information beyond the capabilities of the multi-body systems, it would allow improved countermeasure development through more detailed prediction of performance.

A simpler finite element model of human bones could be developed if …

Test Methods And Results For Sensors In A Pre-Crash Detection System, Charles Birdsong, Peter Schuster, John Carlin, Daniel Kawano, William Thompson

Mechanical Engineering

Automobile safety can be improved by anticipating a crash before it occurs and thereby providing additional time to deploy safety technologies. This requires an accurate, fast and robust pre-crash sensor that measures telemetry, discriminates between classes of objects over a range of conditions, and has sufficient range and area of coverage surrounding the vehicle. The sensor must be combined with an algorithm that integrates data to identify threat levels. No one sensor provides adequate information to meet these diverse and demanding requirements. However the requirements can be met with an optimal combination of multiple types of sensors. Previous work considered …

Evaluation Of Cost Effective Sensor Combinations For A Vehicle Precrash Detection System, John Carlin, Charles Birdsong, Peter Schuster, William Thompson, Daniel Kawano

Mechanical Engineering

The future of vehicle safety will benefit greatly from precrash detection -the ability of a motor vehicle to predict the occurrence of an accident before it occurs. There are many different sensor technologies currently available for pre-crash detection. However no single sensor technology has demonstrated enough information gathering capability within the cost constraints of vehicle manufacturers to be used as a stand alone device. A proposed solution consists of combining information from multiple sensors in an intelligent computer algorithm to determine accurate precrash information. In this paper, a list of sensors currently available on motor vehicles and those that show …

Enhancing Student Learning In Mechanics Through Rapid-Feedback, Jennifer Kadlowec, John Chen, Dexter Whittinghill

Mechanical Engineering

In this project our goal is to improve student learning in engineering mechanics courses. The aim to improve learning was accomplished by providing rapid feedback to students of their understanding of key concepts and skills being taught. The feedback system acts as a catalyst to encourage students, working in pairs, to assist each other in correcting misconceptions or deepening each other’s understanding of the concept or skill at hand. Furthermore, the system allows the professor to assess the students’ level of comprehension or misconception in a just-in-time fashion, and thus guide the pace of covering the material. The feedback is …

A Cartilage Growth Mixture Model For Infinitesimal Strains: Solutions Of Boundary-Value Problems Related To In Vitro Growth Experiments, Stephen M. Klisch, Robert L. Sah, Anne Hoger

Mechanical Engineering

A cartilage growth mixture (CGM) model is linearized for infinitesimal elastic and growth strains. Parametric studies for equilibrium and nonequilibrium boundary-value problems representing the in vitro growth of cylindrical cartilage constructs are solved. The results show that the CGM model is capable of describing the main biomechanical features of cartilage growth. The solutions to the equilibrium problems reveal that tissue composition, constituent pre-stresses, and geometry depend on collagen remodeling activity, growth symmetry, and differential growth. Also, nonhomogeneous growth leads to nonhomogeneous tissue composition and constituent pre-stresses. The solution to the nonequilibrium problem reveals that the tissue is nearly in equilibrium …

Characterization Of Crack Propagation During Sonic Ir Inspection, Jacob Kephart, John Chen, Hong Zhang

Mechanical Engineering

Sonic IR is an emerging, thermal-based, nondestructive evaluation (NDE) technique. Typically a short burst of high power acoustical energy is injected into an object being studied and certain types of defects heat up and is detected using a thermal imaging camera. This inspection technique is very fast, lasting only a few seconds for total inspection time. However due to many uncertainties in the inspection process it has yet to be adopted widely by industry. There are many unknown parameters governing sonic IR, which need to be understood before it becomes a widely used NDE technique. This paper shows that under …

Application Of Nonlinear Dynamics Tools For Diagnosis Of Cracked Rotor Vibration Signatures, Jerzy T. Sawicki, Xi Wu, Andrew L. Gyekenyesi, George Y. Baaklini

Mechanical Engineering

The nonlinear model of the cracked Jeffcott rotor is investigated, with the particular focus on study of rotor’s vibrational response using tools of nonlinear dynamics. The considered model accounts for nonlinear behavior of the crack and coupling between lateral and torsional modes of vibrations. Load torque is applied to the rotor which is laterally loadedwith a constant radial force (gravity force) and unbalance excitation. The co-existence of frequencies of lateral modes in the frequency spectra of torsional mode are characteristics of the coupling response of lateral and torsional vibrations. When only the lateral excitations are applied, vibration amplitude bifurcation plot …