bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Decoupling of the Passive and Active Components of Muscle Force
Authors: Karakostas Tasos E. , Parnianpour Mohamad , Berme Necip , Pease William S. , Quesada Peter M. , Simon Sheldon R.
Published: December 2021

Decoupling of the passive and active components of the muscle force is appealing in musculoskeletal modeling to investigate human movement strategies and pathologies. This study assessed the feasibillity of decoupling the contribution of the passive element from the contribution of the active element using computer simulations. The Soleus muscle of the lower extremity was investigated during plantar flexion. It was found that the contribution of the passive element to muscle force was dependent on the level of muscle excitation. Even isometric contractions with respect to the muscle-tendon length, will result in non isometric conditions for the muscle fibers as the activation level of the muscle varies.
Senior Designs to Aid the Disabled: The UAB Experience
Authors: Eberhardt Alan W. , Vogtle Laura K. , Edwards Gary
Published: December 2021

This paper presents a review of two years experience regarding senior design projects to aid persons with disabilities, for mechanical engineering students at the University of Alabama at Birmingham (UAB). The efforts are funded by the National Science Foundation and are aimed at developing alternative, low cost, custom devices to aid specific disabled individuals or targeted groups. A collaboration has been established with UAB Occupational Therapy and United Cerebral Palsy of Birmingham (UCP), who have provided projects which combine depth in both engineering and life sciences. The “UAB experience” described in the following includes project selection, development, student advising and overall significance. Completed designs are listed, along with efforts to bring the products to a marketable level.
Engineering Analysis of Side Release Seat Belt Buckles
Authors: Stilson John M. , Vega Henry V.
Published: December 2021

The automotive seat belt buckle has only one purpose: as a safety device it must properly restrain individuals in a collision. In the engineering and design of a seat belt buckle the dynamic conditions that prevail during collisions must be considered during the design process. In the conventional side release buckle’s thirty year life it has been established it is susceptible to release due to inertial, shock, and impact loading. An engineering analysis of the acceleration levels that induce inertial unlatching of a type 6 seat belt buckle was explored. A test apparatus was designed and fabricated to subject the buckle to inertial accelerations which would simulate the transmission of g-forces through the vehicle’s structure when subjected to impact conditions. Accelerometers were used to measure the g-forces that were induced in to the drop fixture and seat belt buckle housing during testing procedures. The g-forces experienced by the drop test fixture and belt buckle determined that when convergent conditions occur during collisions the seat belt buckle will unlatch. The basic engineering of the side release buckle incorporates a guard that will prevent unlatching in some frontal collisions. But when the loading conditions of real world collisions converge toward a low belt load and high buckle accelerations inertial unlatching can occur. The conditions of the convergence interval in the course of a collision requires engineering analysis.
Human Head-Neck Kinetics Under Whiplash Loading
Authors: Yoganandan Narayan , Pintar Frank A. , Cusick Joseph F. , Hollowell James P.
Published: December 2021

The objective of the study was to determine the biomechanics of the human head-neck complex secondary to whiplash loading. Intact human cadaver head-neck complexes were prepared by maintaining the integrity of the skin and musculature around the ligamentous column. Retroreflective targets were inserted into the bony articulations of the cervical spine at all levels. The specimens were rigidly fixed to a six-axis load cell at the distal end. Instrumentation consisted of triaxial angular velocity sensors and accelerometers on the cranium. A linear accelerometer was attached to the distal end of the preparation. The specimens were subjected to dynamic loading at speeds ranging from 1.6 to 4.2 m/s. They were placed on the slider of the mini-sled pendulum which applied the whiplash loading pulse from the posterior to the anterior direction. The input pulse was measured in terms of acceleration-time histories. Principles of continuous motion analysis were used to determine the kinematics of the head-neck complex as a function of time. The specimens were radiographed pre- and post-test. Results indicated that the structure undergoes continuous change in the head-neck curvature. Initially, the cranium lags the cervical spine resulting in a reverse curvature, the upper cervical spine undergoes flexion with a concomitant extension of the lower cervical spine, and finally, the head catches-up with the lower cervical spine resulting in a single curvature. Increasing velocities/accelerations produced nonlinear increases in extension moment, axial and shear forces, and head-neck kinematics. These strength and kinematic information add to our knowledge of the understanding of the biomechanics of the human head-neck under whiplash.
Development of a Retro-Fit Anti-Whiplash Seat Cushion Based on Studies of Accident Victims and Human Volunteers
Authors: Tencer Allan F. , Mirza Sohail , Martin Dennis , Goodwin Vern , Sackett Roger , Schaefer Jerry
Published: December 2021

Whiplash injuries of the cervical spine due to rear-end motor vehicle accidents continue to be the single most expensive medical claim for insurers (Insurance Institute, 1995). The diagnosis of whiplash is confounded by a general lack of objective symptoms, but may result in a long lasting chronic condition (Spitzer, 1996). Head restraints were introduced in US vehicles in 1969, to limit rearward angular displacement of the occupant’s head relative to the torso (Code of Federal Regulations).
Redundant Muscular Force Analysis of Lower Extremity During Swing Phase
Authors: Huang Changhua , Yang Nianfeng , Wang Rencheng , Zhu Changhong , Jin Dewen
Published: December 2021

Swing phase of the human gait is defined as the time period during the bottom of foot is off the ground. At the beginning of swing phase there is a flexion of knee joint, which is important to form the clearance between the ground and the toe. In 1992 Winter referred to that the average clearance is about 1.29cm in a normal swing phase and mainly dominated by the flexion of the knee joint. If there doesn’t have enough flexion of knee, the tiptoe will collide with the ground during the swing phase. Otherwise, in this case, there must be an additional trunk movement to raise the coxa joint or to abduct the thigh. Actually this is not a normal gait and looks very clumsy as you can imagine a patient’s gait. However, regarding how to obtain the enough flexion of knee, people have different views on that whether the muscles of lower limb are actively involved and how much contribution they make. Mochaon and McMahon (1980) stated that at a certain extent of initial angular velocity, the clearance can be obtained without muscles’ involving. Mena (1981) also referred to that an approximated normal swing phase could be simulated without applying moments on the coxa joint and/or knee joint. But later, researchers got different results. Yamaguchi (1990) found that there should be muscular forces in swing phase through a simulation analysis of 8-DOF musculoskeletal model with dynamic programming method. With limiting solution method. Collins (1995) got the similar conclusion. In 1996. Piazza and Delp presented a 3-DOF musculoskletetal model to study the effects of muscular forces on knee flexion, they decreased or increased the strength of the neural innervation signals of some muscles and made a thorough observation on the movement of lower limbs. In their discussions the importance of rectus femoris (RF) in knee flexion was emphasized.
A Model for Fracture of Bridging Fibers in Titanium Metal Matrix Composites
Authors: Ghonem Hamouda
Published: December 2021

This paper investigates the fatigue failure of SiC fibers bridging a fatigue crack in unidirectional reinforced titanium matrix composites. For this purpose, an experimental/computational fiber fracture model is developed on the basis of the occurrence of two damage events taking place along a bridging fiber. These events are the time-dependent evolution of axial stresses and the simultaneous strength degradation of the fiber due to cyclic-related damage processes. The stress evolution in a fiber is calculated using the finite element method employing a cylinder model of a fiber embedded in a cracked matrix phase. The model considers the visco-plastic behavior of the matrix phase at elevated temperature loadings. The failure strength of the as-received SiC fiber are determined through a series of monotonic tension, residual fatigue strength and fatigue-life tests performed on SiC fibers at different temperatures. In order to take into account the notch-like effects resulting from the presence of fiber coating cracks and possible deflection of fiber/matrix interfacial cracks, the fatigue strength of the as-received SiC fiber was modified using an elastic stress localization. The resulting fatigue strength of bridging fibers was found to be about 56% less than the corresponding strength of as-received fibers. The fiber stress evolution curve and the modified fatigue strength curve were then combined to predict the life of bridging fibers. Results of the model are compared with those obtained experimentally for bridging fibers in SiC/Timetal-21S composite subjected to load conditions including low and high loading frequency at room temperature, 500 and 650 °C.
Toughness Improvement in Composite Materials Using Ductile Reinforcements
Authors: Wetherhold Robert C. , Bös Joachim
Published: December 2021

Ductile reinforcements can supply fracture toughness to a polymer matrix by pulling out and by plastically deforming. In the case of metal reinforcements that are not in a toughened condition, there may be more toughening to be gained when the fibers remain in the matrix and plastically deform rather than pulling out. These fibers can be said to have an unused plastic potential. When these fibers bridge a crack, their plastic deformation causes a rapid rise in the force which is trying to pull out the fiber. Because of this, the shape of the fiber must be adjusted along its length if it is to remain anchored and contribute its plastic work. The use of anchored, ductile fibers provides a new design axis that brings new possibilities not achievable by the current research focus on the fiber-matrix interface. This paper describes the experimental pullout of aligned ductile fibers from a polymer matrix, and indicates the effect of the shape and embedded length of the fiber on the toughness increase of the composite. Anchored, plastically deforming fibers are shown to provide a major improvement to the toughening. Even for unoptimized ductile fibers, the calculated toughening improvement equals or exceeds the toughening available from current short glass or graphite fibers.
Analysis of Domain Switching Zone Near a Crack Tip in Piezoceramics
Authors: Chang I. , Sun C. T.
Published: December 2021

In this paper, a finite element program in conjunction with domain switching criterion was developed to analyze domain wall switching and its effect on the near tip stress field in piezoelectric materials containing a crack. Domain switching zones in the vicinity of the crack tip corresponding to various combined electric and mechanical loads were obtained. It is found that the size, shape and mode (90° or 180° switching) of domain switching zone near the crack tip depend on the direction as well as magnitude of the applied electric field. For a positive electric field (same as the poling direction), 90° domain switching occurs behind the crack tip, and the zone increases as the applied positive electric field increases. If the applied electric field is negative, then a 180° domain switching zone appears ahead of the crack tip while a 90° domain switching zone exists behind the tip. Moreover, the stress field near the crack tip is found to be significantly affected by the domain switching.
Electrical Fatigue Degradation for Dissimilar Poled Regions in PZT-5H
Authors: Chaplya Pavel M. , Carman Gregory P.
Published: December 2021

This paper describes an ongoing investigation into understanding the fatigue degradation of piezoceramic materials. The focus of this study is to evaluate large stresses developed between dissimilar oriented domains and their relationship to the nature and mechanics of crack initiation. An innovative specimen configuration is proposed to accelerate the fatigue test that typically takes months to perform. The specimens contain a notch separating polarized regions engineered at the macroscopic level. The specimens are electrically cycled under quasi-linear condition introducing local polarization reversal and domain wall motion. The notch is closely monitored for crack initiation and degradation of piezoelectric coefficients and permittivity is recorded. Results indicate that cracks develop in the material on both the macro and micro levels between dissimilar poled regions. It is believed that crack shielding of the electric field results in property degradation.
Constitutive Modeling of 3-D Stress Induced Phase Transformation in Polycrystalline NiTi SMA
Authors: Lagoudas Dimitris C. , Qidwai Muhammad A.
Published: December 2021

A thermomechanical description of the martenstitic phase transformation and the associated shape memory effect in polycrystalline NiTi shape memory alloys (SMAs) is presented. The Kuhn-Tucker optimality conditions, constraints on the evolution equations for transformation strain find the form of transformation function are obtained naturally through the principle of maximum transformation dissipation. Various transformation functions are investigated and a generalized Drucker-Prager type transformation function is proposed. Numerical results of the model based on different transformation functions are compared with experimental results to determine their accuracy to predict SMA characteristics like tension-compression asymmetry, negative volumetric transformation strain and pressure dependence.
Optimal H∞ Control of Structural Vibrations Using Shape Memory Alloy Actuators
Authors: Sun Jian , Shahin Ali R.
Published: December 2021

This paper investigates robust control problem of structural vibrations using shape memory alloy (SMA) wires as actuators. The mathematical model for these SMA actuators is derived with emphasis in model uncertainty. The linearization of the relation between stress and temperature dynamics of SMA actuators is analyzed for active control. To handle the uncertainties caused by the linearization and the neglected high frequency dynamics, optimal H∞ control was employed to design a controller. An example is used to demonstrate the design procedures and the control system is tested in a nonlinear environment.
New Controller and Observer Design Methods Tailored to Smart, Flexible Structure Control Applications
Authors: Yedavalli Rama K.
Published: December 2021

In this paper, we summarize the research being carried out by the author and his group of graduate students on new control and observer design methods specifically tailored towards to control of smart and flexible structure applications. The new approaches are tailored to this specific application in the sense that they take into account the various types of available measurements and provide controllers and observers in terms of the various combinations of measurement variables. This approach of tailoring the controller and observer structure around the available measurement models has significant advantages over traditional approaches. Specifically these approaches introduce two new frameworks for controller and observer design, namely “Reciprocal State Space Framework” and “Matrix Second Order Framework”. Currently State Space Framework is a popular framework for control systems design in the sense that designers always transform the dynamic model of their application into state space form and then carry out the standard design techniques of this framework. However, we argue that there are many applications in which the dynamics, measurement models and performance constraints are such that it is unnecessary and cumbersome to force this transformation and instead the design can be carried out more easily in these newly introduced frameworks that are compatible with the plant dynamics, measurement models and performance constraints. Using these frameworks, simple control and observer designs are carried out with application to the problem of control of smart, flexible structures.
Modeling and Study of the Quasi-Static Behavior of Piezoceramic Telescopic Actuation Architectures
Authors: Berner Neal T. , Brei Diann E.
Published: December 2021

Piezoelectric stacks are often used in smart structures applications that demand high forces. However, there are numerous applications that require slightly more displacement than is available from stacks and the requirements allow room for some force to be sacrificed to obtain the displacement. A new type of piezoelectric actuation architecture, referred to as telescopic, was designed to meet the need for moderate displacement amplification (one to 20 times) while still producing large forces. This architecture internally leverages the piezoelectric strain by a series of cascading cylinders uniquely connected by end caps such that they “telescope” out when activated. This paper presents an analytical model to predict the force-deflection behavior of this actuator with compliant end caps. The compliance in the end caps governs the quality of the performance and is one of the main design drivers. To aid in evaluating this new architecture, the effect of other architectural losses, such as gap size and number of cylinders, is presented along with a comparison to the current state of the art.
A Composite Sandwich Structure With Embedded MEMS-Based Vibration Sensing
Authors: Pochiraju Kishore
Published: December 2021

This paper presents a sandwich composite architecture suitable for embedding MEMS-based accelerometers for long-term vibration monitoring or to act as sensors in adaptive structures. The presented architecture is designed around multi-axis accelerometers and temperature sensors that are commercially available. These devices also integrate sophisticated sensor compensation and data acquisition hardware into a single integrated circuit chip package. The paper presents the stiffness modeling of a sandwich composite with embedded accelerometers based on classical lamination theory. The first order shear deformation theory is used to compute the free vibration response of the sandwich composite. Solutions are presented for the free-vibration response of the sandwich beam under fixed-free boundary conditions. Results presented also include the response obtained from the MEMS-accelerometer when coupled to a thick cross-ply laminate under fixed-free boundary conditions.
Experimental Flutter and Buffeting Suppression Using Piezoelectric Actuators and Sensors
Authors: Suleman Afzal , Moniz Paulo A. , Costa António P.
Published: December 2021

Experimental buffeting and gust alleviation response results are presented for a sweptback flat wing model using piezoelectric actuators to control bending and wing tip camber shape. Model response was sensed by a small piezoceramic wafer mounted at the root. Two actuation strategies were implemented: the traditional actuators mounted at the root were used to provide structural damping, and a shape control mechanism using a pair of actuators near the wing tip were used to change the airfoil camber shape. Results obtained from wind-tunnel tests of the wing model are presented for the open- and closed-loop systems. The results of this experimental study show that piezoelectric actuation is effective in attenuating vibration and the wake-induced buffet response over the range of parameters investigated. Also, the airfoil camber shape control increases remarkably the efficiency of the system, by using a controlled change of lift in order to produce the required bending moments.
Vibration Control of Beams Using Electro-Magnetic Damping Treatment
Authors: Oh J. , Poh S. , Ruzzene M. , Baz A.
Published: December 2021

A new class of structural damping treatments is introduced. This class is the Electro-Magnetic Damping Treatment (EMDT) which relies in its operation on a viscoelastic damping layer sandwiched between two magnetic layers. Interaction between the magnets generates magnetic forces that enhance the compressional damping mechanism of the viscoelastic layer. With proper tuning of the magnetic forces, in response to the structural vibration, undesirable resonances and catastrophic failures can be avoided. The fundamentals and the underlying phenomena associated with the EMDT are investigated theoretically and experimentally.

A finite element model is developed to describe the interaction between the dynamics of flexible beams, the viscoelastic damping layer and the magnetic layers. The validity of the developed finite element model is checked experimentally using aluminum beams treated with EMDT patches. The beam/EMDT system is subjected to sinusoidal excitations and its multi-mode response is monitored when the magnetic layers are activated or not. Several control strategies are considered to activate the magnetic layers including simple PD controllers. The performance of the uncontrolled and controlled system is determined at various operating conditions. Comparisons with conventional Passive Constrained Layer Damping (PCLD) treatments emphasize the potential of the EMDT treatment as an effective means for controlling structural vibrations.
Control of Wave Propagation in Periodic Composite Rods Using Shape Memory Inserts
Authors: Ruzzene M. , Baz A.
Published: December 2021

Longitudinal wave propagation is controlled using shape memory inserts placed periodically along rods. The inserts act as sources of impedance mismatch with tunable characteristics. Such characteristics are attributed to the unique behavior of the shape memory alloy whereby the elastic modulus of the inserts can be varied up to three times as the alloy undergoes a phase transformation from martensite to austenite. With such controllable capability, the inserts can introduce the proper impedance mismatch necessary to impede the wave propagation along the rods.

An analytical model is presented to study the attenuation capabilities of the composite rods and to determine the influence of the various design parameters of the inserts that can control the width of the pass and stop-bands. The numerical results demonstrate the potential of shape memory alloys in controlling the dynamics of wave propagation in rods. Furthermore, the obtained results provide a guideline for designing inserts that are capable of filtering out selected excitation frequencies through proper adjustment of the geometry of the inserts as well as their activation strategies.
Active Damping by Acceleration Feedback Control and Redistribution of Stresses in the Structure
Authors: Bayon de Noyer Maxime P. , Roberts Patrick J. , Hanagud Sathya V.
Published: December 2021

In most structures, fatigue critical areas are associated with regions of high stresses. Passive stiffening of structures usually displaces these high stress regions. Thus, for most applications, active vibration control is preferred. However, the question of whether an active vibration control scheme involving a set of actuators will reduce stresses in the whole structure or create high stress areas in the vicinity of the actuators arises. In this paper, the stresses induced by an active vibration control system based on the use of an offset piezoceramic stack actuator with acceleration feedback control are investigated. Using a modal analysis of the actuator acting on a cantilever beam, a low frequency approximation of the actuator is developed in the form of a spring and two driving forces. Based on this approximation, a 3-D finite element simulation of the closed loop active vibration control system is developed and the closed loop stresses are studied.
Re-Evaluation of Arteriovenous Cooling of the Blood Supply to Human Brains
Authors: Zhu Liang
Published: December 2021

The purpose of this work is to evaluate the capacity of the heat loss from the carotid artery in human brain and thus, to provide indirect evidence of the existence of selective brain cooling (SBC) in humans during hyperthermia. A theoretical model is developed to describe the effects of local blood perfusion and vascular geometry on the thermal equilibration in the carotid artery based on the blood flow measurements and the anatomical vascular geometry in the human neck. A theoretical approach is used to estimate the potential for cooling of blood in the carotid artery on its way to the brain by heat exchange with its countercurrent jugular vein and by the radial heat conduction loss to the cool neck surface. It is shown that the cooling of the arterial blood can be as much as 1.3 °C lower than the body core temperature, which is in agreement with previous experimental measurements of the temperature difference between the tympanic and body core temperatures. The model also evaluates the relative contributions of countercurrent heat exchange and radial heat conduction to selective brain cooling. It is found that these mechanisms are comparable with each other. Results of the present study will help provide a better understanding of the thermoregulation during hyperthermia. They can be used to guide the design of future experimental investigations of the mechanism of SBC.
Freezing Response of Mammary Tissue: A Mathematical Study
Authors: Elliott Gloria D. , McGrath John J.
Published: December 2021

Cryosurgery, the use of low temperatures to devitalize neoplastic tissue, has become an accepted treatment modality for many cancers such as those of the liver and prostate. Recently, the application of cryosurgery to human breast malignancies has been explored (Staren et. al, 1997, Pham and Rubinsky, 1998). Breast cancer will affect 1 in 9 women over the course of their lifetime (American Cancer Society, 1997). Although there are a wide variety of therapies available to treat this disease, the broad pathological spectrum of patients with breast cancer necessitates newer and better treatments before these numbers will decline.

The composition of human mammary tissue is highly varied (age, body mass, and hormone dependent) making the application of cryosurgery to this tissue complex. Although the preponderance of breast cancer lesions occur in post-menopausal patients, women of all ages are affected by this disease. More importantly, lesions persist in all types of breast tissue. If cryosurgery is to become a viable therapy for breast cancer, it is important to understand the range of responses expected from the different tissue compositions, and, if relevant, identify the tissue types most suited to cryo-based therapies. To this end, an understanding of the response of these various classes of breast tissue to freezing can be accomplished using accurate heat and mass transfer models.

Based on a review of basic human breast histology during all stages of mammary gland development, several different categories of human breast tissue were chosen for constitutional analysis. The volumetric dominance of each of the different tissue constituents was determined and then using this information, the volume-averaged thermal properties for each category calculated. A preliminary analysis, utilizing basic heat conduction equations and effective heat transfer properties, was performed to understand if, in a pure conduction sense, the various categories of breast tissue would respond differently to the same applied freezing protocol, and if so, which components were thermally most relevant. This analysis, although not completely descriptive of the physical situation occurring during an actual cryosurgery protocol, represents the first steps in determining the morphological features of mammary tissue which must be taken into consideration in future modeling efforts.
Cryopreservation of an Engineered Skin Equivalent: The Apoptosis Paradigm
Authors: Baust John M. , Van Buskirk Robert G. , Baust John G.
Published: December 2021

The emergence of the tissue engineering sciences has led to an immediate need for cryopreservation protocols compatible with cell survival, cell-matrix binding and “scaffold” integrity. While numerous problems exist related to directional restrictions in cryoprotectant transport in tissue models, recent findings have demonstrated that the induction of specific molecular events, especially gene regulated cell death (apoptosis) is of significance. Accordingly, we report on a new strategy for the successful cryopreservation of a human skin equivalent.

The integration of an intracellular-type cryopreservation solution containing dimethyl sulfoxide with and without apoptotic inhibitors provides a successful model for tissue preservation. With optimized formulations, post-thaw improvement of viability upwards of three-fold has been demonstrated when compared with traditional preservation methodologies. We conclude that 1) the use of an intracellular-type cryopreservation medium, Hypothermosol®, can improve post-thaw tissue construct integrity and cell viability, and 2) the inclusion of apoptotic inhibitors significantly improves cryopreservation outcome.
Practical Considerations for Large-Scale Cryopreservation of a Tissue Engineered Human Dermal Replacement
Authors: Applegate Dawn R. , Liu Kang , Mansbridge Jonathan
Published: December 2021

Tissue engineering is redefining the field of transplantation by providing a readily available, off-the-shelf supply of consistent, easy to use, safe and effective products. Successful design and scale-up of both tissue growth and preservation processes have enabled maintenance of tissue integrity, functionality and viability from product manufacture to end-use and afforded clinical efficacy, feasibility of large-volume distribution and cost-effectiveness.

Advances in tissue preservation are being realized through extension of mathematical models and biological principles for isolated cells to bench-scale tissue systems. Hence, implementation problems inherent to large-scale systems are not often considered. Furthermore, the effects of preservation on tissues are not always tested in vivo. This paper addresses the practical obstacles to the design and implementation of a large-scale cryopreservation process. The effects of cryopreservation on in vivo tissue functionality including alteration of cell signal transduction pathways and expression of stress proteins in response to cryopreservation are also reviewed.
Thermal Stress Modeling of the Freezing of Biological Tissue
Authors: Rabin Yoed , Steif Paul S.
Published: December 2021

The extent of injury of biological tissues by freezing is influenced by many factors such as the cooling rate, the thawing rate, the minimal temperature achieved, the number of repeated freezing thawing cycles, and the presence of cryoprotectants. The mechanisms of cryo-destruction may generally be separated into two groups; the first is related to the freezing process within the phase transition temperature range (typically between 0 and −22°C), while the second group is related to further destruction after phase transition has completed. Destruction mechanisms of the first group are related to heat transfer, mass transfer, and chemical equilibrium in the intracellular and extracellular solutions. Destruction mechanisms after the phase transition has been completed are related to mechanical stresses in the frozen state. Mechanical stresses develop when changes in density occur nonuniformly in the tissue, a consequence of the presence of temperature gradients. The current presentation gives an up-to-date report on ongoing research to model the freezing of biological tissues and to measure their physical properties. The mechanical boundary condition at the freezing front is emphasized in this presentation, and examples for typical cases of cryosurgery and cryopreservation are discussed.
Interface Shape Control in a Cylindrical Directional Solidification Stage
Authors: Neils Christopher M. , Hayes Linda J. , Diller Kenneth R.
Published: December 2021

A numerical model of 1-D heat transfer and freezing in water has been used to support the development of thermal controls for an optical-axis directional solidification stage. By placing the observer’s point of view on the ice growth axis, this new cryostage improves the microsopic resolution with which cross-sections of growing ice dendrites can be observed. This arrangement also permits a large phase interface (1-cm diameter) so that the dendrite dimensions are not constrained by contact with the container surfaces. The numerical model simulated directional solidification with a constant chilling rate on one boundary. When the initial temperature was equal to the melting point, the interface speed was constant. An initial temperature above the melting point led to an accelerating interface when the second boundary was insulated and a decelerating interface when the second boundary temperature was fixed at the initial temperature.
An Experimental Investigation of the Effects of Microencapsulated Phase Change Material in Grinding Fluid Performance
Authors: Lee Jae M. , Shen Chi-Hung
Published: December 2021

This report documents an experimental study in the evaluation of the grinding performance of three metalworking fluids containing Microencapsulated Phase Change Material (MPCM) slurry. The results showed that wheel wear and surface finish were improved substantially in two cases while the performance became worse for the third fluid. There was significant deterioration of the microparticles because of the high shearing action of the circulating pump.
On Environmental Vibration Power Spectra and Accelerated Testing for Medical Devices
Authors: Wu Jingshu , Zhang Ruichong , Stevens Karl K.
Published: December 2021

This paper proposes field-testing-based power spectra of vibration in such environments as helicopters and ground vehicles. The spectra could then be used as important input data to guide accelerated testing, quality analysis and design for medical devices (or products) used in the aforementioned transportation means. Specifically, a broad spectrum of environmental vibration is first measured in a series of field vibration tests at various locations inside the transportation means and at different operational conditions (e.g., take-off, cruise, and landing conditions if medical devices are used in helicopters). Consequently, comprehensive field-testing-based power spectra are constructed, in an attempt to catch the inherent nature of random vibration environment in each and every type of the transportation means, which is not adequately specified in standard codes. As one of the applications of the proposed spectra, accelerated random vibration testing for medical devices used in either helicopters or ground vehicles is proposed, which could be used not only for product field life prediction but also for its consequent reliability analysis and design.
Smooth Asymmetric Indentation of a Finite Elastic Layer
Authors: Zhou Minggang , Schonberg William P.
Published: December 2021

Standard methods of indentation analysis use a beam theory solution to obtain an overall load-displacement relationship and then a Hertzian contact solution to calculate local stresses under the indenter. However, these techniques are only applicable in a fairly limited class of problems: previous modeling efforts have shown that the stress distribution in the region of contact will differ significantly from a Hertzian one when the contact length exceeds the thickness of the beam. In such cases, point contact can no longer be assumed and Hertzian relations are not valid. The indentation model developed herein is an improvement over current GLOBAL/LOCAL approaches in that it uses an elasticity solution to establish the load-displacement relationship at the contact site. The solution technique is applied to two end conditions: (1) simple supports, and (2) fixed ends. Superposition of appropriate elasticity expressions results in systems of Fredholm integral equations of the second kind that are solved numerically. Maximum contact stresses are obtained and compared with the predictions of the previous GLOBAL/LOCAL model. The validity of the solutions presented is assessed by comparing the results obtained to the predictions of modified beam theory solutions.
Advanced Technological Pre-College Education Program in Composite Manufacturing
Authors: Abrate Serge , Lindsey Jefferson F. , Weston Alan , Rivers Jon , Dill William
Published: December 2021

This article describes a National Science Foundation sponsored project to promote technological education with a focus on composites manufacturing. This project has four components: (1)the promotion of careers in Technology to students in grades 7–11; (2) summer camps for students grades 7–11; (3) short courses for high school teachers; (4) developing new courses at the undergraduate level. For each component of the project, a rationale, detailed content, delivery methods, and assessment methods will be discussed.

Experience indicates a need to reach secondary school students to make them aware of careers in Technology and related educational opportunities at two-year and four-year institutions and to present a positive and attractive image of the field. Our efforts are directed towards students in grades 7–11. To reach a maximum of students in a large geographic area using several approaches:

1. Presentations using distance learning facilities that allow interactive audio/video presentations at different sites. Faculty members on campus can communicate with six or more sites simultaneously and present computer-based materials, videos, and conduct live demonstrations.

2. School visits. Many schools do not have access to site for interactive video presentations.

3. A web site developed for the project contains regularly updated information about the project, information about composite materials, and the field of technology. Interested parties can register for various programs by filling out the appropriate forms on the web.

4. Special events such as National Engineers Week and Open House Days are used to establish personal contacts.

This paper describes how the presentations are delivered, their contents, and how effective they are in promoting a positive image of technology.

Another important component of this project is that each institution offers summer camps for students in grades 7–11 and short courses for high school teachers. Each of these activities concentrate on one specific technical area and offer both a general view of that area and how it can lead to rewarding careers in industry, and direct hands-on experiences.
A Finite Element Analysis Study of Non-Linear Behavior in a Bolted Connection
Authors: Englund Richard B. , Johnson David H. , Sweeney Shannon K.
Published: December 2021

A finite element analysis (FEA) model of the interaction of a nut and bolt was used to investigate the effects of sliding, friction, and yielding in a bolted connection. The finite element model was developed as a two-dimensional, axisymmetric system, which allowed the study of axial and radial loading and displacements. This model did not permit evaluation of hoop or torsional effects such as tightening or the helical thread form.

Results presented in this paper include the distribution of load between consecutive threads, the relative sliding along thread faces, and the stress distribution and regions of yielding in the model. Finally, a comparison to previous, linear analysis work and to published experimental data is made to conclude the paper.
On Designing an Efficient Deburring Tool Path
Authors: Hassamontr Jaramporn , Dornfeld David A.
Published: December 2021

Due to the lack of edge finishing information on a part, the process planner usually designs a deburring tool path to cover all edges with low feed rates. This is to ensure that all part edges are within tolerance. With the presence of edge finishing information, however, it is possible to design the deburring tool path to cover only certain part edges while still maintaining the tolerance requirement. In this paper, the problem of planning such an efficient deburring tool path is formulated as a Travelling Salesman Problem. A few examples are used to illustrate the concept.
Decision Making in Developing Reconfigurable Manufacturing Center for Programmable Force Fit Insertion
Authors: Zhang Bopeng , Zheng Li , Xu Jiaqu
Published: December 2021

Most papers dealing with insertion related-assembly consider mainly loose fit insertions, but in machine building industries nearly 25–35% insertion operations are force fit insertion and are mainly completed manually, some times with the aid of a press machine. In this paper decision making in developing a reconfigurable manufacturing center for performing force fit insertion is presented. A special force fit insertion end effector and a dual mode fixture are developed then combined with a machining center for performing force fit insertion automatically. Functional requirements generation and descision making for conceptual design are explained. A prototype is established, it can perform programmable force fit insertions successfully.
Chatter Suppression With Multiple Time-Varying Parameters in Turning
Authors: Yang Fulun , Zhang Bi , Yu Junyi
Published: December 2021

This paper presents a new method, multiple time-varying parameter (MTVP) turning for chatter suppression. Compared to the single time-varying parameter (STVP) turning, the new method uses both time-varying spindle speed and time-varying rake angle to suppress chatter. The paper provides theoretical analyses on the MTVP turning and experimental results to justify the analytical results. It compares the effects of chatter suppression between the MTVP and STVP turnings, and discusses the possible mechanisms of chatter suppression. The paper then concludes that the MTVP turning method is more effective in chatter suppression than the STVP turning method because of the combined effect of the multiple time-varying parameters. It is demonstrated that the MTVP turning method can suppress chatter by 80%, and can be applied to suppress all kinds of chatter in a machining process.
Mechanistic Model for Tapping Process With Emphasis on Process Faults and Hole Geometry
Authors: Dogra Ajit Pal S. , Kapoor Shiv G. , DeVor Richard E.
Published: December 2021

A mechanistic approach for modeling the tapping process is presented. A methodology for computing chip load is developed for an arbitrary tap geometry. The mechanics of cutting for tapping is analyzed, considering it as an oblique cutting phenomenon. The effects of tap geometry (tap diameter, thread pitch, number of flutes, flute helix angle, tooth rake angle, and thread type), workpiece geometry (hole diameter and hole depth), process parameters (spindle speed and tap penetration depth), and process faults (tap runout, axis misalignment, and drilled hole geometry) are incorporated in the model. The model is calibrated using drilling experiments and is validated by comparing experimental tapping results for Aluminum 319, Aluminum 356, and Gray Cast Iron. In most cases, the tapping forces were predicted within 10% of the experimental values.
Cutting Force Modeling and Optimization in 3D Plane Surface Machining
Authors: Feng Hsi-Yung (Steve) , Su Ning
Published: December 2021

The prediction and optimization of cutting forces in the finishing machining of 3D plane surfaces using ball-end milling are presented in this paper. The cutting force model is developed based on the mechanistic modeling approach. This improved model is able to accurately predict the cutting forces for non-horizontal and cross-feed cutter movements typical in 3D finishing ball-end milling. Optimization of the cutting forces is used to determine both the tool path and the maximum feed rate in 3D plane surface finishing machining. The objective is to achieve highest machining efficiency and to ensure product quality. Experimental results have shown that the cutting force model gives excellent predictions of cutting forces in 3D finishing ball-end milling. The feasibility of the integrated process planning method has been demonstrated through the establishment of optimized process plans for the finishing machining of 3D plane surfaces.
Parallel-Process (Simultaneous) Machining and its Stability
Authors: Ozdoganlar O. Burak , Endres William J.
Published: December 2021

This paper presents a mathematical perspective, to complement the intuitive or practice-oriented perspective, to classifying machining operations as parallel-process (simultaneous) or single-process in nature. Illustrative scenarios are provided to demonstrate how these two perspectives may lead in different situations to the same or different conclusions regarding process parallelism. A model representation of a general parallel-process machining system is presented, based on which the general parallel-process stability eigenvalue problem is formulated. For a special simplified case of the general system, analytical methods are employed to derive a fully analytical stability solution. Thorough study of this solution through eigenvector analysis sheds light on some fundamental phenomena of parallel-process machining stability, such as dependence of the stability solution on phasing of the initial conditions (disturbances). This establishes the importance, when employing numerical time-domain simulation for such analyses, of specifying initial conditions for the multiple processes to be arbitrarily phased so that correct results are achieved across all spindle speeds.
Modeling of Tool Wear Acceleration in Relation to the Reinforcement Percentage in Cutting of Metal Matrix Composites
Authors: Li Xiaoping , Seah W. K. H.
Published: December 2021

A comprehensive study of the tool wear mechanism in cutting of metal matrix composites (MMCs) and its dependence on the percentage of reinforcement in the MMCs is presented. The results from experimental cutting of Aluminium alloy-Silicon Carbide Metal Matrix Composite (Al-SiC MMC) with tungsten carbide tools show that the main mechanism of tool wear in cutting of Al-SiC MMC includes two-body abrasion and three-body abrasion. The abrasive wear of the tool is accelerated when the percentage of the reinforcement in the MMC exceeds a critical value. The wear acceleration is caused by the interference between the reinforcement particles. The interference is associated with a critical weight percentage of the reinforcement in the MMC. The critical weight percentage of reinforcement is a function of the densities of the reinforcement and the matrix as well as the size of the reinforcement particles and the radius of the tool cutting edge. It does not vary with cutting conditions. An analytical model for the critical reinforcement percentage of MMCs is developed and verified with experimental results. The model is used to develop a map showing the critical reinforcement percentages of MMCs varying with the size of the reinforcement particles and the radius of the tool cutting edge.