Mechanical Engineering Commons^™

A Growth Mixture Theory For Cartilage With Application To Growth-Related Experiments On Cartilage Explants, Stephen M. Klisch, Silvia S. Chen, Robert L. Sah, Anne Hoger

Mechanical Engineering

In this paper, we present a growth mixture model for cartilage. The main features of this model are illustrated in a simple equilibrium boundary-value problem that is chosen to illustrate how a mechanical theory of cartilage growth may be applied to growth-related experiments on cartilage explants. The cartilage growth mixture model describes the independent growth of the proteoglycan and collagen constituents due to volumetric mass deposition, which leads to the remodeling of the composition and the mechanical properties of the solid matrix. The model developed here also describes how the material constants of the collagen constituent depend on a scalar …

Body Concept Design For Pedestrian Head Impact, S. Iskander Farooq, Peter J. Schuster

Mechanical Engineering

In 1996, the European Enhanced Vehicle Safety Committee, Working Group 17 (EEVC WG17) proposed -a set of impact procedures to evaluate the pedestrian injury risk of vehicle fronts. These procedures address three aspects of pedestrian protection -head impacts, lower limb impacts, and thigh impacts -through vehicle subsystem tests. The criteria assessed during these impact tests are affected by the design of most parts of the vehicle body front-end.

One of the challenges to vehicle design introduced by these tests is the impact of an adult pedestrian headform to the top of the fender. The proposed acceptance level for Head Injury …

Ultrasonic Technique For Investigation Of The Effect Of Grid-Generated Turbulence On Sound Wave Propagation, Tatiana A. Andreeva, William W. Durgin

Office of the Provost Scholarship

This paper concerns an experimental study of the effects of the grid-generated turbulence on the propagation of acoustical waves in a wind tunnel. Turbulence effects are investigated using ultrasound time-of-flight method, employing counter-propagating ultrasonic pulses. Turbulence effects are an important source of error in the active probing of the atmosphere using sound sources. The emphasis is on the propagation time fluctuations and their interpretation using theoretical analysis of Kolmogorov.

Vibration-Based Crack Diagnosis In Rotating Shafts During Acceleration Through Resonance, Jerzy T. Sawicki, Xi Wu, George Y. Baaklini, Andrew L. Gyekenyesi

Mechanical Engineering

The dynamic response of a cracked Jeffcott rotor passing through the critical speed with constant acceleration is investigated analytically and numerically. The nonlinear equations of motion are derived and include a simple hinge model for small cracks and Mayes' modified funciton for deep cracks. The equations of motion are integrated in the rotating coordinate system. The angle between the crack centerline and the shaft vibaiton (whirl) vector is used to determine the clsoing and opening of the crack, allowing one to study the dynamic response with and without the rotor weight dominance. Vibration phase response is used as one of …

The Biomechanical Aspects Of Pedestrian Protection, Krishnakanth Aekbote, Peter Schuster, Sunny Kankanala, Srini Sundararajan, Stephen W. Rouhana

Mechanical Engineering

In this paper a biomechanical basis for pedestrian protection is presented based on reviews of epidemiological and biomechanical studies conducted over the last three decades. Epidemiological studies reveal the nature and cause of pedestrian crashes and injuries sustained in the field. The various factors that influence pedestrian crashes and fatalities such as pedestrian demographics, time and location of crash, type of vehicles involved and their design characteristics, impact speeds, and nature and severity of injuries sustained are covered in the epidemiology section. The biomechanical studies identify the injury mechanisms and the biomechanical tolerances. Several biomechanical studies that attempt to identify …

Focus On The Job In Hand: When Usb 2.0 Technology Is Employed In Test And Measurement Signal Analyzer Hardware, Life Can Become So Much More Simple, Charles Birdsong, Dave Galyardt, James Zhuge

Mechanical Engineering

No abstract provided.

Educating Engineering Students In Entrepreneurship, William W. Durgin, Donald N. Zwiep

Office of the Provost Scholarship

Since it’s founding in 1865, the faculty, students, and alumni of Worcester Polytechnic Institute have been responsible for the establishment of nearly all the manufacturing industry in the region. Beginning with the Norton Company, a world-wide abrasives manufacturer now owned by Saint Gobain, to recent biotechnology companies, they have combined confidence, innovation, and resourcefulness to continuously accomplish what is now referred to as technology transfer to form start-up companies. By following the historical development of these firms, we seek to determine some of the traits and environmental factors that have fostered the continual entrepreneurial success of the founders.

Worcester Polytechnic …

Stability And Heat Transfer Characteristics Of Condensing Films, James C. Hermanson, Peder C. Pedersen, Jeffrey S. Allen, M. A. Shear, Z. Q. Chen, Andreas N. Alexandrou, William W. Durgin

Office of the Provost Scholarship

No abstract provided.

A Taxonomy Of Scheduling Problems In Semiconductor Device Test Operations, Tali Freed, Robert C. Leachman, Kenneth H. Doerr

Industrial and Manufacturing Engineering

Semiconductor device test facilities differ not only by production volume and tester brands. The complexity of the devices and the characteristics of the testers affect the scheduling methodologies as well. Goals and strategies vary from one firm to another, leading to a variety of objectives and performance measures. Due to random yield lot size is variable and lot priorities are common. Changeover times are oftentimes sequence-dependent. Since semiconductor device testing systems are very costly, scheduling methods that increase the throughput of the facility are financially significant. In this paper we describe a variety of semiconductor device testing environments, develop mathematical …

A Mixture Of Elastic Materials With Different Constituent Temperatures And Internal Constraints, Stephen M. Klisch

Mechanical Engineering

A novel treatment of the 2nd Law of Thermodynamics and the development of general thermomechanical constraints are introduced for a mixture of two elastic materials in which the constituents may have different temperatures. First, a homothermal quasi-static process at a common mixture temperature is introduced. Part I of the 2nd Law of Thermodynamics is invoked to assert that the Clausius integrals are path-independent, which leads to a prescription, or an identification, of the partial entropy functions. Then, two assumptions are introduced that establish the values of the partial entropy functions for general processes, including those for which the constituent temperatures …

Development And Application Of Streakline Visualization In Hypervelocity Flows, P. Lemieux, H. G. Hornung

Mechanical Engineering

A method for visualizing streaklines in hypervelocity flows has been developed. The method uses the high temperatures produced in hypervelocity flows to ablate small amounts of sodium deposited onto a wire stretched across the flow and to broaden the lines in the sodium spectrum. By using a dye laser, tuned to a wavelength close to one of the sodium D-lines, as the light source in shadowgraph or Schlieren visualization, streaklines seeded with sodium become visible through absorption and/or enhanced refractivity. The technique has been used to investigate the stability of the shear layer produced by the curved bow shock on …

A Venture Capital Fund For Undergraduate Engineering Students At Rowan University, Anthony J. Marchese, John C. Chen, John L. Schmalzel

Mechanical Engineering

All engineering students at Rowan University are required to take the 8-semester Engineering Clinic sequence wherein multidisciplinary student teams engage in semester-long design projects. In addition to projects that are funded by local industry, faculty research grants or departmental budgets, a Venture Capital Fund has been created, which is specifically ear-marked for the development of original student inventions. Funding of up to $2500 per student team per semester is competitively awarded based on student-generated proposals to the Venture Capital Fund, which has been created through a series of grants from the National Collegiate Inventors and Innovators Alliance (NCIIA). To qualify …

A Theory Of Volumetric Growth For Compressible Elastic Biological Materials, Stephen M. Klisch, Timothy J. Van Dyke, Anne Hoger

Mechanical Engineering

A general theory of volumetric growth for compressible elastic materials is presented. The authors derive a complete set of governing equations in the present configuration for an elastic material undergoing a continuous growth process. In particular, they obtain two constitutive restrictions from a work-energy principle. First, the authors show that a growing elastic material behaves as a Green-elastic material. Second, they obtain an expression that relates the stress power due to growth to the rate of energy change due to growth. Then, the governing equations for a small increment of growth are derived from the more general theory. The equations …

Automatic Compact Disc Transfer For Quality Assurance Testing, Ravi P. Ramachandran, John Chen, Linda M. Head, John L. Schmalzel, Hampton C. Gabler

Mechanical Engineering

The purpose of this project was to design, build and test a low cost prototype that transfers compact discs (CDs) from a spindle to a computer based testing station. This will speed up the CD production/testing interface and eliminate the need for manual operation. Along with a heavy product design technical component, the project included a real life educational experience for the four students who got credit for a one year advanced senior project. Various designs were considered and the optimal design (based on cost and performance) was prototyped.

Shock Layer Instability Near The Newtonian Limit Of Hypervelocity Flows, H. G. Hornung, P. Lemieux

Mechanical Engineering

The curved bow shock in hypersonic flow over a blunt body generates a shear layer with smoothly distributed vorticity. The vorticity magnitude is approximately proportional to the density ratio across the shock, which may be very large in hypervelocity flow, making the shear layer unstable. A computational study of the instability reveals that two distinct nonlinear growth mechanisms occur in such flows: First, the vortical structures formed in the layer move supersonically with respect to the flow beneath them and form shock waves that reflect from the body and reinforce the structures. Second, the structures deform the bow shock, forming …

Computer-Aided Engineering For Tool Design In Manufacturing Engineering Curriculum, Daniel J. Waldorf

Industrial and Manufacturing Engineering

At Cal Poly – San Luis Obispo, a variety of tool design issues are covered in a junior-level manufacturing engineering course called Tool Engineering. In the course, designing fixtures – for any process – is a major component of the content. The process of designing a fixture is similar to the method a mechanical engineer would use to design a new product. The course is therefore an excellent opportunity to teach design principles to manufacturing engineers. This project involves an attempt to introduce computer-aided methods, including the finite element method (FEM), for analysis of tool design into the Tool Engineering …

Teaching Factory, Sema E. Alptekin, Reza Pouraghabagher, Patricia Mcquaid, Daniel Waldorf

Industrial and Manufacturing Engineering

Academia must develop a new approach to teaching in order to better prepare engineering students to function efficiently and adjust readily within the framework of the factories in the real world. Some engineering programs emphasize theory, while others emphasize application as isolated blocks. The "Teaching Factory" being developed at Cal Poly combines both theory and applications. It makes use of state-of-the-art industrial grade production equipment, computer hardware and software in the form of the following two systems: 1) a functioning "real" factory hardware environment, and 2) a Production Planning and Control Center.

Determination Of Statistical Characteristics Of Isotropic Turbulence, Tatiana A. Andreeva, William W. Durgin, F. J. Weber, Hamid Johari

Office of the Provost Scholarship

Ultrasonic flow measurement technology has the potential to significantly improve flow measurement accuracy beyond that presently achieved. However, current applications fail to achieve theoretical accuracies because of turbulence effects on ultrasonic wave transit time. Herein, the ultrasonic flowmeter equation is reconsidered, where the effects of turbulent velocity and sound speed fluctuations are included. The result is an integral equation for the corresponding correlation functions. In this paper experimental velocity data are used to solve this integral equation analytically. As a result, some statistical characteristics of the turbulent flow are developed and can explain the limitations of measurement accuracy observed in …

Ultrasonic Beam Propagation In Turbulent Flow, William W. Durgin, F. J. Weber, Hamid Johari

Office of the Provost Scholarship

A study was conducted to examine how a coherent sound burst, such as those used in an ultrasonic flowmeter, crosses a turbulent flow field. Many ultrasonic flowmeters use a time of flight method to determine the mean flow. This measurement method sends sound waves at some angle across a velocity field between two transducers, and the time required for the sound burst to cross this distance is measured on the order of nanoseconds. The system then reverses so that the sound wave burst is sent in the opposite direction. Knowing the distance traveled, the local average sound speed, and the …

An Electronically Tunable Resonator For Noise Control, Charles Birdsong, Clark J. Radcliffe

Mechanical Engineering

Many engineering systems create unwanted noise that can be reduced by the careful application of engineering noise controls. When this noise travels down tubes and pipes, a tuned resonator can be used to muffle noise escaping from the tube. The classical examples are automobile exhaust and ventilation system noise. In these cases where a narrow frequency band of noise exists, a traditional engineering control consists of adding a tuned Helmholtz resonator to reduce unwanted tonal noise by reflecting it back to the source (Temkin, 1981). As long as the frequency of the unwanted noise falls within the tuned resonator frequency …

A New Portable, Pc Based, Usb Powered Dynamic Signal Analyzer, Charles Birdsong, George Ma, James Nieters, Justin Tang, Caine Yu

Mechanical Engineering

A new USB powered portable 4-channel real time Dynamic Signal Analyzer and its automotive applications are described. The design and architecture lend themselves to real time NVH measurements and analysis in the field, in-vehicle or on production lines. Built-in signal conditioning provides for direct sensor power while the embedded DSP provides for signal processing on-board. Performance and implementation of FFT, digital filters and order analyses are presented.

Hide Glue Applicator, Chris Campo, Benjamin Carrasco, Elias Saliba

Mechanical Engineering

This study investigates the challenges inherent in applying hide glue in the crafting of violin and other stringed instruments. Hide glue, derived from animal collagen and protein, is essential for creating durable bonds that allow for necessary adjustments during fabrication. However, its meticulous heating and maintenance requirements pose logistical obstacles for luthiers lacking viable alternatives. To tackle this issue comprehensively, our project comprises several key components.

Initially, we conducted an in-depth analysis of the hide glue application process, delineating procedural steps and techniques to establish our design criteria and constraints. This foundational understanding formed the basis for further exploration. Additionally, …

A Comparison Of Two Actuators For A Semi-Active Helmholtz Resonator, Charles Birdsong, Clark J. Radcliffe

Mechanical Engineering

Two electro-mechanical actuators are examined for a semi-active Helmholtz resonator acoustic device. The device is used to reflect narrow band noise back to the source in an acoustic duct. The controller and actuator are used to tune the system on-line allowing optimum performance over a range of operating conditions. Actuator. dynamics play an important role in the controller design and the operation of the device. Two variations of an electro-mechanical actuator are considered here. The first uses a dual voice coil speaker with local feedback compensation and the second uses the same speaker without the compensation. It is shown that …

A Growth Mixture Theory For Cartilage, Stephen M. Klisch, Robert L. Sah, Anne Hoger

Mechanical Engineering

In this paper we present a model of growth for cartilaginous tissues in which there exists a saturated solid matrix composed of multiple constituents that may grow and remodel independently of each other. Klisch and Hoger recently developed a general theory of volumetric growth for a mixture of ν-1 growing elastic materials and an inviscid fluid, which included a treatment of two special types of internal constraints that are relevant to cartilage. Here, that theory is specialized to construct a cartilage growth model. This theory allows the constituents of the solid matrix to grow independently of each other, and can …

Development And Validation Of A Pedestrian Lower Limb Non-Linear 3-D Finite Element Model, Peter Schuster, Gopal Jayaraman

Mechanical Engineering

Lower limb injury is becoming an increasingly important concern in vehicle safety for both occupants and pedestrians. To enable vehicle manufacturers to better understand the biomechanical effects of design changes, it is deemed beneficial to employ a biomechanically fidelic finite element model of the human lower limb.

The model developed in this study includes long bones (tibia, fibula, femur) and flat bone (patella) as deformable bodies. The pelvis and foot bones are modeled as rigid bodies connected to the femur and tibia/fibula via rotational spring-dashpots. The knee is defined by scanned bone surface geometry and is surrounded by the menisci, …

Plastic Solder Paste Stencil For Surface Mount Technology, Christopher K. Wong, Daniel Waldorf

Industrial and Manufacturing Engineering

Solder paste masks or stencils are an integral part of the manufacturing process for surface mount PCBs. This study examines the feasibility of a process for rapid creation of a solder paste stencil using thermoplastic material. CNC laser cutting of the stencil geometry is replacing traditional use of chemical etching on metal sheets to produce stencils. Laser cutting has been used to improve process speed, accuracy, and cost. This research attempts to continue to simplify and reduce costs in the stencil making process by proposing as the stencil material a common thermoplastic that can be cut easily and quickly using …

Global Projects Prepare Wpi Students For The 21st Century, William W. Durgin, Donald N. Zwiep

Office of the Provost Scholarship

The WPI project based curriculum, which emphasizes discovery based learning are an alternative to the traditional information transfer process, has proved successful in delivering global engineering education. More than 25% of the learning process of the students is integrated into two formal projects, the Major Qualifying Project (MQP) which is designed as a capstone for professional technical competence and the Interactive Qualifying Project (IQP) which relates science and technology to societal concerns and student needs. Both the MQP and IQP may be completed on- or off-campus. Currently, over 50% of the graduating class will have completed one of the projects …

Stability And Heat Transfer Characteristics Of Condensate Fluid Layers In Reduced Gravity, James C. Hermanson, Andreas N. Alexandrou, William W. Durgin, Peder C. Pedersen, Jeffrey S. Allen

Office of the Provost Scholarship

The focus of this ground-based program is the study of film condensation phenomena under variable, reduced-gravity conditions. Experimental tests, combined with numerical modeling, are employed to gain an improved understanding of the fundamental fluid physics responsible for condensate film growth, film instability and the resulting interfacial motion under variable gravity, and the corresponding implications for heat transfer. There has been relatively little research on the mechanisms operative at the film interface between condensed liquid and its vapor under reduced gravity conditions. Of particular interest are the stability characteristics of the condensate layer, and how they differ from those of films …

Product Flexibility In Selecting Manufacturing Planning And Control Strategy, Emine Persentili, Sema E. Alptekin

Industrial and Manufacturing Engineering

The manufacturing systems capable of producing several products simultaneously are frequently subject to changes in product types due to demand fluctuations. In such systems a product flexible manufacturing planning and control (MPC) strategy is needed to change from one product type to another with minimum deterioration to system performance levels. The objective of this research is to develop a systematic analysis and evaluation approach in order to compare the MRP-push and JIT-pull strategies quantitatively based on a product flexibility measure. A new product flexibility measure is developed based on the sensitivity to change concept and presented together with the implementation …

Ultrasonic Monitoring Method And System For Wake Turbulence Useful At Runways, Hamid Johari, William W. Durgin

Office of the Provost Scholarship

Two techniques for detecting vortices and their associated circulation are disclosed. The first is termed a closed path configuration, and the second is termed the dual path configuration. These techniques are useable for the detection of wake turbulence especially in the vicinity of airport runways, which results from wing tip vortices generated by aircraft during take-off and landing. The systems are similar in that they use ultrasonic measurement techniques to determine the circulation about defined areas. The circulation is reflective of the vorticity associated with trailing vortices, which are manifest within the area.