bluuebunny/crossref_metadata_2025 huggingface dataset:
A Multi-Scale Model for Cell Adhesion and Deformation
Authors: N’dri Narcisse , Shyy Wei , Tran-Son-Tay Roger , Udaykumar H. S.
Published: November 2021

A multi-scale computational approach for studying the adhesion kinetics and deformation of a cell on a substrate is presented. This method breaks the computational work into two separate but interrelated domains. At the cellular level, a continuum model satisfying the field equations for momentum transfer and mass continuity is adopted. At the receptor-ligand or molecular level, the bond force is mechanically represented by a spring, and the formation and dissociation of bonds are characterized by a reversible two-body kinetic model. The model demonstrates that as the reverse reaction rate increases, the receptor-ligand bonds break faster, and the opposite is observed when the forward reaction rate increases. As expected, the cell peeling time increases as the number of ligands increases until it equals the number of receptors. The peeling time becomes shorter when the spring constant or slippage constant is larger. Furthermore, as the cell velocity increases during the peeling process, the maximum bond length increases while the total peeling time decreases. Based on the information from the two modeling levels, dynamics of membrane movement can be computed, illustrating that the cell mechanical properties and surrounding fluid dynamics affect the receptor-ligand kinetics, and that these effects need to be included in any realistic cell-surface interaction models.
The Effect of an External Magnetic Field on the Impurity Distribution in an RF-FZ Silicon Crystal During the Growth Process
Authors: Munakata Tetsuo , Someya Satoshi , Tanasawa Ichiro
Published: November 2021

The impurity concentration distribution in a silicon crystal during the floating zone (FZ) growth process under radio-frequency (RF) heating and the effect of an externally applied magnetic field on the impurity distribution in the crystal have been investigated numerically. The main purpose of the study is to clarify the characteristics of the impurity distribution in the silicon crystal under the RF-FZ crystal growth process, and the effect of an externally applied magnetic field on such an impurity distribution. The numerically obtained characteristics on impurity distribution in the crystal are as follows. In the case of excluding the external magnetic field, impurity concentration in the crystal varies due to the fluctuation of the melt flow. If we apply an external magnetic field, such impurity variation in the crystal disappears due to the stabilizing effect of the external magnetic field. Further, the crystal growth rate is decreased, the impurity concentration in the crystal is also decreased. The impurity segregation coefficient does not affect the impurity distribution in the crystal.
New Steam Turbine Test Vehicle for the Verification of Improved Efficiency Power Generation Steam Turbines
Authors: Willey Lawrence D. , Maughan James R. , Hill J. Michael , Walsh Dennis J.
Published: November 2021

The worldwide demand for electricity is continually increasing. Deregulation in the power generation business is driving rapid changes in the global energy market. This results in higher premiums on steam turbine efficiency and opportunities to structure several new Steam Turbine products to meet these challenging requirements. The “Dense Pack” high pressure section replacement and offering is one of the newest advanced designs to address these needs by delivering more power for the least amount of fuel. The intense competition to serve the electric power utility industry combined with the drive for new product introductions to be of the highest development life-cycle quality demands that verification of performance benefits be established very early in the new product development process.

To answer this and establish pre-field installation credibility with customers, a new multi-stage Steam Turbine Test Vehicle (STTV) has been designed and constructed. The turbine faithfully models a typical, 4-admission, large utility steam turbine and preserves geometric and flow similarity while operating at reduced pressure. The basic train is comprised of a nominal 3.5 MW (4700 hp) test turbine, a 5:1 speed reducing load gear, and two tandem 3.0 MW (4000 hp) dynamometers. The thermodynamic cycle is straight through superheated steam entering the turbine through a turbine bowl pressure regulator control valve and exhausted to the atmosphere via a back pressure control valve and roof-mounted silencer. A rigorous Design for Six Sigma (DFSS) process was used to establish the test turbine facility and to ensure all of the new product program objectives were met.

A detailed description of the facility is given with discussion of the major sub-systems, prototypical model hardware, unique steampath instrumentation, and the test procedures used to ensure accurate, repeatable data. The timeline for accomplishing the design, construction, and early testing is chronicled. Key test results are summarized including baseline testing to validate the new test facility, testing of the “Dense Pack” aerodynamic design methodology for power generation steam turbines, and the performance evaluation of developments such as new shaft, advanced aerodynamics and bucket tip seals.

In addition to developing the new design technologies and verifying their predicted efficiency increases, the Steam Turbine Test Vehicle is key for conducting Form-Fit-Function studies. Model hardware built using the standard manufacturing methods and materials intended for production parts provides invaluable insight ahead of finalizing production specifications. New features such as advanced seals and Integral Cover Buckets (ICB) benefit from being more thoroughly understood in terms of assembly and procedures ahead of new product production.
Self-Excited Oscillation of a Collapsible Tube
Authors: Wang J. W. , Low H. T. , Chew Y. T.
Published: November 2021

This paper considers the effect of flow-system parameters on collapsible tube flow during low-frequency oscillation; of particular interest are the reservoir head and flow resistance at the upstream and downstream, and the fluid inertia at the downstream. Experimental measurements were obtained, under zero upstream transmural pressure, for the pressure and flowrate in terms of their mean values and waveforms; also presented were the instantaneous tube shapes during an oscillation cycle. It was found that the upstream reservoir head and flow resistance determine the mean flowrate but do not affect the pressure and flow waveforms. Different waveforms were obtained even when the downstream reservoir head and flow resistance were arranged to achieve identical mean condition of pressure and flowrate. An increase in the downstream flow resistance or fluid inertia has the effect of reducing the amplitude and frequency of oscillation.
Flow Characteristics of Pulsating Flow Obstructed by an Array of Square Rods
Authors: Murata Hiroyuki , Sawada Ken-ichi , Kobayashi Michiyuki
Published: November 2021

A series of flow visualization experiments of pulsating flow obstructed by an array of square rods was carried out to investigate its characteristics. When the pulsation is absent, Karman vortices shed periodically from each rod. When the pulsation period is relatively long compared with the shedding period and its amplitude is large, the flow is stabilized during the accelerating phase and, during the decelarating phase, the flow is destabilized and Karman vortices break down. When the pulsation period is shorter than shedding period and its amplitude is large, the flow pulsation controls the generation and breakdown of the Karman vortices. A numerical simulation code was developed and compared with the experimental results. When the pressure gradient parameter of the code is changed sinusoidally with time, computed results become the pulsating flow. Time variations of the streamwise pressure gradient and cross-sectional averaged velocity show similarity between the experimental and computed results.
Evaluating and Improving Locomotive Crashworthiness Using LS-DYNA
Authors: Kokkins Stephen J. , Kasturi S. Kash , Kong Wayne , Punwani S. K. John
Published: November 2021

Representative structural models of locomotives, other rail vehicles, and other potential colliding objects were combined into moving consists which were then subjected to various collision scenarios. The LS-DYNA dynamic finite-element modeling code was utilized to realistically simulate collisions and guide understanding and improvements of the locomotive structures. This incorporated the effects of the collision interactions, plus critical non-linear material and structural behavior, buckling, fracture, kinematics, and wayside interactions of the vehicles.

The types of collisions included: locomotive-headed consists striking standing consists obliquely fouling the Right Of Way, headed both by freight cars and other locomotives; locomotives striking loose, loaded intermodal containers dislodged from opposing cars on adjacent track. Work on multiple coupled locomotive overrides in direct consist collisions is now being conducted.

The effects of varying parameters such as collision speeds, location and orientation of the colliding vehicles, and structural improvements were explored and quantified. Also, the effects of some structural design modifications such as stronger collision posts and cab structure were evaluated using this process.

Verification studies to date have shown good correlation between the analytical simulations and observed outcome of actual historical accidents.
Progress in Railway Mechanical Engineering: 1999–2000 Report of Survey Committee—Passenger and Commuter Rail Vehicles and Components
Authors: Hesser Kenneth R.
Published: November 2021

This annual ASME committee report covers selected worldwide developments in rail passenger and commuter vehicle equipment, components and systems. The information contained herein was obtained from responses to survey letters sent to the manufacturers of passenger rail vehicles and components, and from a review of trade and technical publications.
Prediction of Progressive Failure of Woven Composites
Authors: Whitcomb John , Tang Xiaodong
Published: November 2021

This paper investigates the effects of geometric non-linearity and material property degradation models on the prediction of progressive failure analyses of woven composites under tensile and compressive loads. Preliminary results presented herein suggest that the degree of difficulty of conducting progressive failure analysis is largely a function of the degree of waviness. The large waviness material exhibits complex behavior and the predictions are very sensitive to the assumed degradation model. The low waviness composite, which is more representative of most structural weaves, does not exhibit such complex behavior, at least on the global scale.
Control of Failure Evolution in 3D Cellular Woven Composite Systems
Authors: Baucom Jared N. , Zikry Mohammed A. , Qiu Yiping
Published: November 2021

This investigation examines the role of porosity in the perforation resistance of 3-D woven fiber reinforced epoxy panels under impact by rigid projectiles at velocities of 100 to 200 m/s. Incident and residual velocities are measured to determine the energy absorption by the target. To compare samples of different areal density, the energy is normalized by the target areal density. The sample responses segregate by porosity, and the more highly porous samples absorb a greater amount of specific energy. The reason for this is unclear but may be due to the deflection of matrix cracks by pores or due to the greater flexibility of the fibers to absorb energy through tensile straining. Although porosity is generally an undesirable property in textile composites, the induction of porosity may result in reduced panel weight without degradation of ballistic performance, a clear advantage for weight minimization.
Crack Growth in Metal-Ceramic Composites
Authors: Agrawal Parul , Sun C. T.
Published: November 2021

This research focuses on the fracture mechanisms in various metal-ceramic composites. The objective was to study the effects of volume fractions, residual stresses and other microstructural features like particle size and contiguity of the constituent phases, on fracture. Neutron diffraction tests were performed to measure residual stresses in these composites. In-situ 3-point bend tests were performed inside the ESEM (Environmental scanning electron microscope) chamber to observe crack growth. It was found that residual stresses and contiguity play dominant roles in fracture and defining the crack path. The correlations between residual stresses and other microstructural features with the crack path and failure mechanisms were established based on experimental observations.
Failure of Laminated Composites at Thickness Discontinuities Under Complex Loading and Elevated Temperatures
Authors: Lee S. , Knauss W. G.
Published: November 2021

Failure initiation of laminated composites with discontinuous thickness has been studied in terms of typical structural load description (tension, shear force and bending moment) rather than in terms of micromechanics considerations. Four types of specimens of different stacking sequence were examined to determine failure initiation, analyzed subsequently via a finite element analysis (ABAQUS), divided into two groups that evoke cross-ply failure, on the one hand, and delamination type failure on the other. For unidirectional fiber orientation in the tension direction and across the interface, failure occurs through cracking and delamination. While the initiation strength for this failure mode is significantly higher than for cross-ply configurations, the residual strength after initiation increases only marginally (10%) beyond the initiation point. For cases involving cross-plies on either side of the interface, failure initiation occurs by matrix cracking. In these cases the residual load bearing capability was 20 to 30% higher than the corresponding failure initiation loads. The data are analyzed in terms of the Tsai-Hill criterion and in terms of an energy release criterion that has been discretized in a manner consistent with a non-singular treatment of the step “discontinuity”. Assuming that time dependent aspects of the failure process are not dominant, elevated temperatures did not change the general results of how bending and tension loads interact; however the magnitude at which the failures occur depends on the temperature, with increasing temperature leading to decreasing load tolerance.
Optimal Design of Stiffened Composite Panel for Performance and Manufacturing Considerations
Authors: Yoo J. , Hajela P.
Published: November 2021

This paper describes a design study in which a stiffened composite wing panel is configured for a combination of performance and manufacturing related requirements. The principal focus of the paper resides in demonstrating the adaptation of newly emergent soft-computing methods for a variety of sub-tasks that constitute the design process. These sub-tasks include function approximations, modeling of processes that lack a good analytical description, and design optimization in a space that consists of a mix of integer, discrete, and continuous design variables. Soft computing techniques discussed in this context include function approximations using back-propagation neural networks, modeling of the composite panel fabrication process using evolutionary fuzzy models, and the application of genetic algorithms and immune network modeling to the optimization problem.
Nonlinear Interaction of Ultrasonic Beams in Air
Authors: Weiguo Dong , King Lim Mong , Xiaoyang Huang
Published: November 2021

Parametric arrays are widely used in underwater environment. Recently, efforts have been made to apply parametric radiation to audio sound reproduction in air. However, some presumptions used in underwater acoustic analyses are not applicable in air, especially for sources with small sizes. A possible solution is to numerically solve the KZK equation, which is the well accepted “exact” model equation for directional acoustic beams. In this paper, a small plane circular piston source is considered and a finite difference technique is used to numerically solve the KZK equation. Experiments are also performed. It is shown that numerical results are in good agreement with the experimental measurements.
Boundary Conditions for a Traveling Web Detaching From a Rotating Cylinder
Authors: Reuter Christoph G.
Published: November 2021

High speed traveling webs appear in a number of technical applications such as plastic foil or paper production machinery and printing machines. Almost all mechanical models for the dynamic behaviour used so far, assume simple support boundary conditions. In reality, in the case of two-dimensional webs immersed in a viscous fluid, a low pressure zone will be present under the web near the point where the web detaches from the rotating drum. Other effects such as adhesion forces may also contribute. Thus, as can often also be seen already by naked-eye examination, the web does not detach tangentially from the drum.

In this paper a mechanical model for small amplitude vibrations of a traveling web with small sag is developed, which takes into account the effect of the above described upstream boundary condition. The web is modeled as a one-dimensional heavy string without bending stiffness. The assumption of quasi-static stretching is made, i.e. infinitely high wave speed is assumed for longitudinal waves.
Key Parameters Affecting Solder Joint Life of Chip Resistors and Chip Capacitors Mounted on Insulated Metal Substrate
Authors: Sangalli Nicoletta , Barker Donald B.
Published: November 2021

Aluminum insulated metal substrate (IMS) is often used as an alternative to FR-4 to enhance heat dissipation in high power applications. Although IMS offers better heat dissipation, the solder joint life of leadless chip resistors and chip capacitors under thermal cycling can decrease. This is due to the higher mismatch of the coefficient of thermal expansion between the ceramic based components and the aluminum board.

This paper has two main objectives. One is to investigate the sensitivity of solder joint life of ceramic chip capacitor and chip resistor mounted on IMS to variations in dielectric thickness, board material, and solder thickness on. This sensitivity analysis is conducted with finite element analysis (FEA) simulation. The other objective is to determine the solder joint life for different resistor sizes at different temperature ranges with FEA modeling and experiment data. These results are presented in terms of design guidelines to be used in the selection of component size, board material, and temperature ranges, given an expected solder joint life.
Application of a Novel Flip Chip Solder Joint Inspection System to Chips on an FR-4 Substrate
Authors: Erdahl Dathan S. , Liu Sheng , Ume I. Charles
Published: November 2021

Because the trend in electronic interconnection technology is toward the development of solder bump technologies, that include flip chips, chip scale packages, multi-chip modules (MCMs), and ball grid array (BGA) packages, solder bump inspection methods must be developed to allow rapid, accurate, and high resolution on-line inspection of joint quality. Although traditional methods can detect some manufacturing defects, they do not actually test the mechanical quality of the connection. A novel solder-joint inspection system has been developed based on laser ultrasound and interferometric techniques. A pulsed laser generates ultrasound on the chip’s surface and the whole chip is excited into vibration modes. An interferometer is used to measure the vibration displacement of the chip’s surface. Solder joints with different qualities cause different vibration responses, acting as constraints on the system. The system was used to inspect the quality of solder joints on a group of flip chips mounted on FR-4 substrates, and the results show the ability of the system to detect defects such as missing solder balls, cracked chips, and gross misalignment.
A Review of Electrically Conductive Adhesive Technology for Use in Surface-Mount Microelectronics
Authors: Rafanelli Anthony J.
Published: November 2021

Interest in alternatives to lead solders continues to increase due to several initiatives addressing the reduction of lead usage and subsequent exposure to the environment. Alternative materials can be categorized into two main groups: electrically conductive adhesives (polymers) and non-lead solders. Over the past ten years, many non-leaded solders have been developed and introduced to the electronics industry. Despite some success regarding processability, several issues still exist regarding use of these materials as “drop-in” replacements for traditional leaded solders, e.g. eutectic tin-lead. This paper provides an overview of the second alternate material group, i.e. electrically conductive adhesives. An attempt is made to compare characteristics of these materials to the tin-lead benchmark. A summary of key material properties is also included. Finally, a position is presented regarding the approaches taken in evaluating these materials as suitable substitutes for tin-lead eutectic solder. Focus is on applications in surface mount technology (SMT) interconnection since solder is the primary bonding medium for interconnection. In general, these materials are acceptable for most applications. Applications under harsh service and environmental conditions, however, would require evaluation on a case-by-case basis.
Characterization of the Performance of Flat Heat Pipes for Electronics Cooling
Authors: Vadakkan Unnikrishnan , Garimella Suresh V. , Sobhan Choondal B.
Published: November 2021

A computational model has been developed to analyze the transient and steady-state performance of flat heat pipes and assess their performance under different operating and geometric parameters, in order to arrive at optimal designs. The model assumes two-dimensional fields for flow and heat transfer and solves the governing differential equations using a finite-difference approach. The wick region of the heat pipe is analyzed using transport equations for a porous medium. The influence of axial heat conduction along the wall, as well as the energy transport in the wick, on the velocity and temperature distributions is examined. The overall performance of the heat pipe is quantified by calculating an effective thermal conductance from the heat input and the temperature drop along the heat pipe wall. Parametric studies are conducted using the model to investigate the dependence of the heat pipe performance on the heat input at the evaporator, the containing wall thickness, and the porosity of the wick.
Rice SPENDULAP: A Laboratory Apparatus to Illustrate Key Concepts in Kinematics, Dynamics, and Control
Authors: Dabney James B. , Ghorbel Fathi H.
Published: November 2021

The Rice SPENDULAP is a spherical pendulum apparatus that is useful for illustrating a variety of important topics in kinematics, dynamics, and control. This paper describes how the SPENDULAP can be used to supplement the classroom so as to enhance students’ understanding of three-dimensional kinematics and dynamics. The paper also describes the use of the SPENDULAP to illustrate key topics in nonlinear systems analysis, such as linearization and the state portrait. Finally, the use of the SPENDULAP as an example for simulation and nonlinear control is described. More information on the SPENDULAP is available at http://dacnet.rice.edu/users/ghorbel/index.html.
Aeroelastic Vehicle Sensor Placement for Feedback Control Applications Using Gain Stability
Authors: Al-Shehabi Abdul G. , Newman Brett
Published: November 2021

Optimal positions for aeroelastic vehicle feedback sensors, which meet design constraints and control requirements, are difficult to determine. This paper introduces a systematic and optimal approach for choosing sensor locations based on gain stability criteria. A steepest descent optimization method with constraints is used to minimize such objective criteria, which are based on the dipole magnitudes for each aeroelastic mode appearing in a traditional Evans diagram for a scalar control loop. Each dipole magnitude term is multiplied by a weight parameter. Rigid-body augmentation characteristics are implicitly accounted for in the type of input-output pairs utilized and in predefined loop compensation structure. Constraints enforcing minimum phase zeros in the transfer function are also considered. A flexible aircraft structure is used as an example to demonstrate this procedure. Results indicate flight control and structural mode control characteristics can be effectively balanced.
Fault Diagnosis of an Internal Combustion Engine With Embedded Radial Basis Function Modules
Authors: Gan Chengyu , Danai Kourosh , Rizzoni Giorgio
Published: November 2021

The application of a modeling compensation method is studied in fault diagnosis. This compensation method relies on embedding single-input single-output radial basis function (RBF) modules within the nonlinear model of the plant so as to provide a basis for closed-form representation of the uncertain components. The weights of these RBF modules are then adapted on-line by the extended Kalman filter (EKF), in tandem with state estimation, to provide a representation of these uncertain components within their range of variation. The improved performance of the EKF-based observer in presence of time-variability has motivated exploring its utility in fault diagnosis of an automotive engine, where its performance is studied in detection of a throttle sensor fault.
Electromagnetic Levitator at Space Power Institute, Auburn University
Authors: Ciocirlan Bogdan O. , Marghitu Dan B. , Beale David G. , Overfelt Ruel A.
Published: November 2021

In this paper, the electromagnetic levitation instrument designed by Space Power Institute at Auburn University is analyzed. An analytical model to compute the Lorentz force that supports the specimen against gravity is proposed. The equation of vertical motion of the specimen is developed and linearized. A fuzzy logic control system designed to stabilize the motion of levitated specimens is also presented.
Detection of Lateral Damping Friction in Surface Textures Presented via a Force Feedback Haptic Interface
Authors: Weisenberger Janet M. , Krier Michael J. , Kreidler Sandra M.
Published: November 2021

Previous work with real surfaces has suggested that variations in the coefficient of surface friction do not affect the judgment of surface roughness. Nonetheless, it is likely that subjects are able to detect changes in frictional characteristics even when judgments of roughness are unaffected. The goal of the present study was to determine whether users of a force-feedback haptic interface could discriminate surfaces containing a lateral viscous friction component from surfaces that did not. Three subjects were tested in an adaptive same-different task, in which they were asked to judge whether two simulated surface textures felt the “same” or “different.” On each trial, one surface contained lateral damping forces in addition to vertical point-source forces, and the other did not. Values of the damping constant for the surface containing lateral damping were adjusted to determine the threshold for discriminating a surface with a lateral damping force from a “frictionless” surface. Results suggest that users are quite able to detect a frictional component even at relatively small lateral forces. These results are considered in view of the notion that for some tasks an accurate rendering of frictional forces may improve task realism.
Algebraic Surface Derivatives for Rendering Virtual Contact Force
Authors: Nelson Donald D. , Cohen Elaine
Published: November 2021

Previous augmented reality displays have rendered crisp virtual walls and virtual objects with finger-surface reactions through haptics feedback devices. The widely used stiffness (or impedance) methods penalize a user’s intrusion into a virtual surface with a force response dependent on the amount of penetration along the contact normal at the virtual proxy location. We present an alternative approach for computing the surface impact response that projects Lagrange multipliers associated with a unilateral surface constraint onto a multivariate surface constraint Jacobian for the case where the two objects (finger and model) do not stick together. Advantages of our method are that the surface Jacobian is already being computed from an exact NURBS-NURBS collision update algorithm previously developed by the authors, and that the force response is accurate to numerical precision; no polygonal or numerical approximations are employed.
Force-Enabled Sculpting of CAD Models
Authors: Buttolo Pietro , Stewart Paul , Chen Yifan
Published: November 2021

Transferring geometrical information between Computer-Aided Design models and physical prototypes is a time-intensive task and as such is one of the critical bottlenecks in the automotive design process. Sculpting of free-form surfaces in force enabled CAD applications could bridge the gap between digital models and certain physical prototypes. In this paper a novel force-enabled surface manipulation method called stick-to-surface/stick-to-pen is presented. During sculpting, the haptic device is constrained to follow the virtual surface, and simultaneously the surface is controlled to follow the device. The trade-off between which follows which is managed by partitioning the Cartesian space into a browsing subspace and a manipulation subspace.
Stress Analysis of Adhesively Bonded Lap Joints of Hollow Shafts Subjected to Torsional Moments
Authors: Nakano Yuichi , Takagi Yukihisa , Sawa Toshiyuki
Published: November 2021

The stress and strain distributions in adhesively bonded lap joints of hollow shafts with dissimilar materials subjected to torsional moments are examined using an axisymmetric theory of elasticity. In the analysis, the joint is modelled as an elastic three-body contact problem, and the hollow shafts, and the adhesive are respectively replaced by finite hollow cylinders. In the numerical calculations, the effects of the ratio of Young’s modulus of the adhesive to that of the shaft, the overlap length, and the thickness of the adhesive on the stress distributions at the interfaces in the joint are clarified. It is shown that the shear stress becomes singular at the ends of the interfaces between the shafts, and the adhesive, and increases near the ends of the interfaces with a decrease of Young’s modulus of the shaft, and of the thickness of the adhesive. For verification of the stress analysis, the strain distribution at an outer surface of an adhesively bonded lap joint was measured and a fairly good agreement was shown by comparing the experimental result with the analytical one.
Opportunities for Crashworthiness Improvement Using Tube Hydroforming
Authors: Morphy Gary E.
Published: November 2021

The automotive industry has and continues to make advances toward the sometimes conflicting goals of make our vehicles safer to use, lighter and better able to perform while achieving attractive appearance and downward cost pressure.

Benefits that hydroforming offers that can improve crashworthiness are reviewed. Brief descriptions of 2 hydroforming methods are given followed by a more detailed examination of wall thickness and cross section expansion. Others include the influence of part design on forming pressure, materials that can be used and part surface complexity.
Design Issues in Tissue Engineered Cartilage Replacement
Authors: Andriacchi Thomas P. , Alexander Eugene J.
Published: November 2021

Tissue engineered replacement cartilage for the treatment of an arthritic joint must sustain the mechanical demands of normal function. Historically total joint replacement has been the primary method for the treatment of severely degenerated joints. The design of a tissue engineered cartilage replacement has a number of parallels with the design of a total joint replacement. Therefore, it is useful to examine the design process of a total joint replacement in the context of designing a tissue engineered cartilage replacement. This presentation will examine the design requirements for the replacement of articular cartilage at the knee.
Morphological Age-Depended Development of the Human Carotid Bifurcation
Authors: Seong Jaehoon , Wakhloo Ajay K. , Lieber Baruch B.
Published: November 2021

The development, significance and function of the human carotid sinus are not clearly understood. The arterial wall of carotid sinus is densely enervated and it contains baroreceptive neural terminals. It has been hypothesized that the dilation, which may involve all vessels of the carotid bifurcation, serves to support pressure sensing. Another hypothesis based on phenomenological observations presumes that the function of the sinus is to slow the blood flow and reduce the pulsatility in order to protect the brain (1). Yet another postulate states that the sinus is an ontogenetic or phylogenic residual. More recently, in vitro and computational models have been used to investigate carotid hemodynamics. Complex flow patterns have been found in the carotid sinus. These patterns have been implicated in the carotid bulb heterogeneity and subsequent development of atherosclerosis at this site.

However, long term development of this unique sinus morphology has not been investigated. It is of both fundamental and clinical interest to form an understanding of the hemodynamics and developmental forces that play a role in remodeling of the carotid bifurcation and maturation of the sinus. This understanding can lead to better prognostication and therapy of carotid disease.

Therefore, a study of the morphological development of the human carotid bulb was initiated. Carotid bulbs from various human developmental stages were evaluated to test the hypothesis that morphology of the sinus reflects an acclimated change in response to alterations in cerebral blood supply with aging. This acclimation attempts to diminish hydraulic losses in the carotid bifurcation through reduced flow disturbances. Under basal conditions, a high level of blood supply to the brain is maintained that consumes about 15% of cardiac output. Furthermore, it may protect the brain from highly pulsatile blood flow conditions and/or the sinus wall from high shear stress.

Initially, we analyzed the sinus morphology and the angle of the carotid bifurcation in four human developmental stages, namely newborn, pediatric, adolescent and adult patients (Groups I, II, III, and IV, respectively). The analysis was performed using biplane digital subtraction angiograms to characterize changes that occur as the brain matures.
Testing of a Novel Hip Prosthesis Design
Authors: Riley Shawn P. , Santare Michael H. , Advani Suresh G. , Miller Freeman
Published: November 2021

Total hip arthroplasty (THA) has been in use with reasonable and increasing success for over 40 years. However, the conventional, long-stemmed, Charnley (1960) implant alters the natural loading in the proximal femur from bending and axial load to more of a shear and circumferential load. This change in load often causes the bone to remodel, which can eventually lead to loosening of the implant. This problem is particularly common among younger, more active THA recipients. Therefore, patients under age 60, who could benefit from THA may be encouraged to postpone surgery to reduce the potential need for future revision surgeries caused by loosened prostheses. The authors’ overall goal in this work was to design and test a new prosthesis that reduces this stress redistribution using a rigorous engineering approach.
Surface Topography and Cartilage Thickness Templates for the Femur and Patella Based on an Average of Healthy Articular Surfaces
Authors: Cohen Zohara A. , Levine William N. , Mow Van C. , Ateshian Gerard A.
Published: November 2021

The patella and femur surfaces of 14 healthy human knee joints were used to create average articular surface topographies and average cartilage thickness maps. The maps are shown to be useful as templates for the identification of lesions on patient-specific thickness maps.
Dynamic and Swelling Behaviors of Porcine Annulus Fibrosus in Compression
Authors: DiDonato D. G. , Justiz M. A. , Gu W. Y.
Published: November 2021

Low back pain is a major socio-economic concern in this country [1, 2]. More than seventy percent of all people have back pain at some point in life, with the annual prevalence of back pain ranging from 15–45%. Although the exact cause follow back pain is unclear, the degenerative changes of the intervertebral disc (IVD), a crucial component of the human spine, have been implicated as a possible primary etiologic factor [1, 3–4]. Since the IVD functions in vivo to provide load support and spine flexibility [1, 2], the relationship between its biomechanical behavior and tissue composition and structure needs to be defined and measured.
A Novel Method for Measuring the Optical Activity of Biopolymers and Application in Measuring Denaturation of Type I Collagen
Authors: Majewski Alexander J. , Sanzari Martin
Published: November 2021

Optical Activity is defined as a property, in which a substance will absorb incident (optical) radiation and / or change its polarization state. Molecules of this type are known as chiral (its mirror image cannot be superimposed upon itself i.e. the molecule has a handedness). Optical Rotatory Dispersion (circular birefringence) occurs when a material exhibits a difference in its index for right-handed (nR) or left-handed (nL) circularly polarized light. In terms of the indices of refraction, the observed rotation is defined as: α = (πd/λo) (nL − nR). Where: nL = index of refraction for left-handed polarization; nR = index of refraction for right-handed polarization; d = path length (sample thickness); λo = wavelength of incident radiation measured in vacuum. We have developed and tested a new instrument that measures the optical rotatory properties of biopolymers. The advantage of this instrument is that it allows a real time measurement of the optical activity of biopolymers; which can be used to monitor samples for changes of state. By using a differential measurement scheme, system errors are minimized and resolution is increased over current measurement techniques. A study of the denaturation process of type I collagen will be presented.
A Clinical Evaluation of Vibration Testing in the Assessment of Osteoporosis
Authors: Kasra Mehran , Grynpas Marc D. , Soric Rajka , Arnaud Sara
Published: November 2021

Bone fracture is one of the most common medical problems which reduces the quality of life of individuals. In the United States, osteoporosis alone causes 1.3 million bone fractures a year, with an annual cost of $5.2 billion dollars. Osteoporosis is a disease in which low bone mass and changes in bone quality and architecture increase the risk of fractures. Women are at greater risk of developing osteoporosis than men. Osteoporosis targets both trabecular and cortical bone (Kanis et al., 1994; Kasra and Grynpas, 1994). Therefore, bone density of cortical bone structures such as ulna and mid-radius may be used as a predictor of osteoporotic fractures (Cummings et al., 1993). Bone quality assessment and predicting the risk of bone fracture is very important in prevention of fracture and proper bone treatment. In the NIH Consensus Development Statement (1984), the need for improved measurement techniques is emphasized.
Role of Trabecular Bone Distribution in Femoral Neck Biomechanics
Authors: Fox Julia C. , Keaveny Tony M.
Published: November 2021

Body weight, habitual postures and activities are the primary determinants of the nature and magnitude of loads acting on the proximal femur, the distribution of which influences the development of the bone structure and geometry (Wolff, 1892). This phenomena, called functional adaptation, has long been an area of interest in the field of bone mechanics, particularly with reference to compensatory geometric remodeling of long bones with decreasing bone mass (Martin et al. 1977; Ruff et al. 1988; Kannus et al., 1996). However, the extent to which compensatory remodeling occurs in the femoral neck remains unclear (Horikoshi, 1999; Beck, 1993). A potential adaptation of the femoral neck may be characterized by the asymmetric distribution of trabecular and cortical bone in the femoral neck cross-section, i.e. there is a disparity in superior and inferior cortical thickness (Bell, 1999; Boyce, 1993), referred to here as an eccentricity.
Biomechanics of Lumbar Spondylotic Degeneration
Authors: Cusick Joseph F. , Kumaresan Srirangam , Bunch Brian , Yoganandan Narayan , Pintar Frank A.
Published: November 2021

Human lumbar spinal columns exhibit different degrees of spondylotic degeneration. However, the biomechanical effects of these changes have not been fully studied. Understanding the potential patterns of such responses relative to the severity of degenerative changes assist in clarifying the influence on clinical and laboratory investigations. This study was conducted to obtain the three-dimensional biomechanical stability parameters of degenerated and non-degenerated spines. The degree of degeneration in disc and facet joints was graded individually for severity allowing evaluation of overall effects as well as individual component influences. Pure moment and complex loading were applied under flexion, extension, and left and right lateral bending modalities. The degenerated columns responded with greater variations in the moment-rotation (pure-moment loading) and force-deflection and moment-rotation (combined loading) than normal spinal columns. Furthermore, the response of the degenerated column depended not only on the overall quality of the spine, but also on the difference in severity and type of components affected. Complex loading showed increased sensitivity to variations in the biomechanical responses compared to pure moment loading. Disc degeneration showed increased changes in rotational stability, whereas facet alterations demonstrated greater effects on axial stiffness.
Biomechanics of Carotid Artery Dissection in Vehicular Accidents
Authors: Sances Anthony , Carlin Fred H. , Daniels David , Cusick Joseph F.
Published: November 2021

Carotid and vertebral artery dissections are often associated with hyperextension of the neck or rapid hyperrotation of the head. In each of these cases, the arteries are damaged by being stretched over the upper cervical vertebra. A dissecting aneurysm ensues in which blood makes its way between the layers of the vessel wall eventually resulting in a thrombosis and cerebral infarct. Typical mechanisms of these injuries in the automotive environment are the absence of a head restraint, shoulder harness trauma, and whiplash. These mechanisms together with blunt trauma and inertial forces are discussed.
LDA Study of the Flow Associated With the Design Differences and Orientations of the Bileaflet Mechanical Prostheses
Authors: Akutsu Toshinosuke , Higucchi Daiki , Taguchi Tomohiro
Published: November 2021

Four typical mechanical bileaflet heart valves (St. Jude Medical, Advancing The Standard, Carbomedics, and Jyros valves) have been tested in the mitral position under pulsatile flow conditions. Measurements of velocity and turbulent stresses were conducted at five downstream locations using a sophisticated cardiac simulator in conjunction with a highly sensitive two-component LDA. Comparison of these flow fields associated with the opening and subsequent accelerating phase of the flow revealed similarity and dissimilarity of the flow field associated with the different valve designs and helped established visualizing the effect of the valve designs and orientations on the flow.
Distribution of Oxygen Tension in Neocortical Areas in the Rat Somatosensory Cortex
Authors: Masamoto Kazuto , Oka Kotaro , Kobayashi Hirosuke , Sannohe Yuki , Takizawa Naosada , Tanishita Kazuo
Published: November 2021

The purpose of this study is to identify the localized differentiation of oxygen transport in the brain. We measured oxygen tension in three neocortical areas (FL, HL, and Tr) of the rat somatosensory cortex by microcoaxial needle electrodes. The structure of neocortical area is characterized by the variation of cell shape, spatial distribution and size, which results in the following three types of the oxygen tension distribution; random, fluctuation, and hypoxia.
Use of Natural Hydroxyapatite for Coating of Titanium for Implantation
Authors: Pal Subrata , Shinde Santosh N. , Roy Sukumar
Published: November 2021

It is welknown that titanium is the best biocompatiable metal available till date. Since commercially pure titanium (cpTi) has satisfactory mechanical properties, including sufficient ductility, together with a thermal expansion coefficient similar to that of hydroxyapatite, corrosion resistance and blood and tissue compatible behavior, it was selected for coating with hydroxyapatite.
Advanced Stochastic Techniques for Jet Engine Component Life Prediction
Authors: Ghiocel Dan M.
Published: November 2021

The paper addresses significant aspects of stochastic modeling for jet engine component life prediction. Probabilistic life prediction for gas turbine engine components represents a very difficult engineering problem involving stochastic modeling of multiple, complex random phenomena. A key aspect for developing a probabilistic life prediction tool is to incorporate, and to be open to modeling advances related to dynamic complex random phenomena, including space-time random variabilities of mission environment and material parameters, aero-elastic interactions, friction at contact interfaces, multi-site fatigue, progressive damage mechanism, including loading interactions, etc.. The paper addresses the main aspects involved in stochastic modeling of component fatigue life prediction for jet engine rotating components, specifically fan blades. The paper highlights the need of the use of stochastic process and field models for including space-time varying random aspects.

Mission speed profiles produced by pilot’s random maneuvers are modeled by pulse non-Gaussian stochastic processes. These pulse processes are approximated using linear recursive models when the cluster effects are not significant. A more general approach, useful when cluster effects are significant, based on a combination of two pulse processes is used. Aero-pressure distribution on blade as well as blade surface geometry deviations due to manufacturing are idealized by using factorable stochastic field models. Also, stochastic field models are used for modeling strain-life and damage accumulation curves. Stochastic damage accumulation models are based on randomized stress-dependent models (nonlinear damage rule models).

The paper also addresses mathematical modeling of stochastic nonlinear responses in multidimensional parameter spaces. Stochastic response surface techniques based on factorable stochastic fields or optimum stochastic models are suggested.

An illustrative example of a jet engine blade is used for discussion and to show the consequences of different modeling assumptions.