bluuebunny/crossref_metadata_2025 huggingface dataset:
In Situ Lumbar Facet Capsular Ligament Strains Due to Joint Pressure and Residual Strain
Authors: Gacek Elizabeth , Ellingson Arin M. , Barocas Victor H.
Published: March 2022

The lumbar facet capsular ligament, which surrounds and limits the motion of each facet joint, is mechanically significant and has been the subject of multiple previous mechanical characterization studies. Those studies, however, were performed on isolated tissue samples and could not assess the ligament's mechanical state in vivo, where attachment to rigid bone and joint pressure forces lead to non-zero strain even when the spine is unloaded. In this work, we quantified these two effects using cadaveric lumbar spines (5 spines, 20 total facet joints harvested from L2-L5). The effect of joint pressure was measured by injecting saline into the joint space and tracking 3-D capsule surface motion, and prestrain due to attachment was measured by dissecting a large tissue section from the bone and tracking motion between the on-bone and free states. We measured joint pressures of roughly 15-40kPa and local 1st principal strains of up to 25-50% for 0.3mL saline injected into the joint space. The largest stretches were in the bone-to-bone direction in regions spanning the joint space. When the ligament was released from the vertebrae, it shrank by 4-5% on average, with local maximum (negative) principal strains of up to 30%. Based on these measurements and previous tests on isolated lumbar facet capsular ligaments, we conclude that the facet capsular ligament's normal in vivo state is in tension, and that the collagen in the ligament is likely uncrimped even when the spine is unloaded.
A Retractable Six-Prong Laparoscopic Grasper for Laparoscopic Myomectomy
Authors: Butters Brenden , Fernández-Galiana Álvaro , Wollin Daniel , Traverso Giovanni , Slocum Alexander , Petrozza John
Published: March 2022

The fixation and manipulation of fibroids during laparoscopic myomectomy is a persistent issue for gynecologic surgeons. In this paper, we present a laparoscopic grasper that, through a sheath-based deployment mechanism, opens into a larger multitoothed grasper within the patient and collapses back for removal. Due to the increased number of contact points with the tumor, the expanded grasper allows for reliable fixation, aiding in manipulation during excision. We describe the nature-inspired design of the grasper from a physical foundation, establish the design theory and practical issues, and present manufacturing and testing of a full-scale 5 mm grasper. The unit was tested on synthetic fibroid models and was able to sustain a 50% higher load before tearing than a common single-tooth tenaculum. This development not only promises to improve fibroid fixation in myomectomy but also its design could be adapted to aid in the fixation of other difficult tissues in laparoscopic surgery.
Numerical Wear Models for Knock-On Chisels in Real Operating Conditions
Authors: Vrublevskyi Oleksandr , Napiórkowski Jerzy , Gonera Jarosław , Tarasiuk Wojciech
Published: March 2022

Recently, attempts have been made to use 3D scanning to evaluate the wear process of working elements. This paper proposes a new approach to develop a wear model based on an in-depth analysis of changes in the shape of a working component of an agricultural machine. For this purpose, chisels of plowshares used under varied soil conditions were analyzed. Numerical models of worn-out working parts created using 3D scanning were the basis for developing the model. Based on the hypothesis of correlative dependence between changes in wear phenomena and the direction normal to the working surface, a new index was obtained: the shape degradation coefficient. The relationship between the shape degradation coefficient and changes in the profile of the working surface was examined to demonstrate the effectiveness of the application of the new wear model compared to field measurements. The results of work surface microstructure tests also confirm the accuracy of the wear presentation concept proposed in this paper.
Design for Manufacturability and Concurrent Engineering in Integrated Product Development Process
Authors: Sun W. , Lau A. C. W.
Published: March 2022

With recent advancements in computer-aided technologies, integrated CAD/CAE/CAM, rapid prototyping and manufacturing, the paradigm of concurrent engineering has been proven as an effective approach for new product development. This approach can reduce product developing time and cost, improve product quality and enhance product competitiveness. This presentation uses an actual rapid product realization case study to highlight how design for manufacturability and concurrent engineering were implemented into an agile product development process by using an integrated design, analysis, and manufacturing approach and applying design for manufacturability for cost and manufacturing processing analyses. The case study shows how modern design and manufacturing technologies realize the dream of an inventor to rapidly develop a product with potential market success.
Case-Based Generation of Design Concepts
Authors: Zhao Wang , El-Gizawy A. Sherif
Published: March 2022

Knowledge accumulated from past design experience would help the design engineer in one of two ways: relating the functional requirements of the artifact being designed to parts, assemblies, and systems, or assembling independent parts, assemblies, or systems to achieve the desired functional requirements. In the natural thinking process of most of the engineering designs, those parts, assemblies, systems are associated with some typical design cases.

In the perspective of domain knowledge transformation (DKT), the process of case-based reasoning (CBR) is a knowledge state transformation from old design cases to a new design solution. This paper attempts to highlight CBR in generating design concepts (solutions) by knowledge-based design system. Starting with a brief introduction of CBR, the discussions focus on the major challenges of deploying the CBR paradigm in the conceptual design of mechanical systems, viz. how to describe cases, represent and retrieve past cases to be used as candidates of a solution to a new design problem, and so forth. These issues are discussed particularly in the light of the design of positioning systems. A case study is presented to illustrate CBR in generating design solutions.
Determination of Tolerance Distribution of a Mechanical Assembly Through Cost Minimization
Authors: Basaly Nadia A.
Published: March 2022

Manufacturing of parts which exactly meet engineering drawings dimensions for experience is known to be impossible. Drawings specify ideal geometry of the form, size, and location for the component features and surfaces. In addition to definition of the ideal geometry’s, the designer defines some region of tolerability around these ideal dimensions realizing that the nature variation exists when producing a part. The objective of this paper is to conduct a tolerance distribution of a mechanical assembly through cost minimization that can be accomplished through consideration of both assembly stack-up and manufacturing cost minimization. The analysis is accomplished by defining the components of the assembly as random variables and their associated tolerances as the standard deviation of the part dimension. This probabilistic approach allows trade-off between the fit of the assembly and the component tolerances as opposed to the typically practiced worst case analysis. The approach is comprised of a three step iterative process. First, tolerance analysis is accomplished to ascertain the assembly fit function based on the desired yield. Secondly, a probability test is completed on the assembly to identify its manufacturing credibility based on the desired yield. Finally, an optimally test is accomplished based on a given cost model to identify the optimum tolerance distribution.
In-Line Skating and Skateboarding: Injury Patterns and Prevention
Authors: Tudor Andrew H. , Fuller Luanda J.
Published: March 2022

The increased popularity of in-line skating and skateboarding has led to an increase of injuries typical to these sports. Protective equipment for skaters and skateboarders has not yet reached the level of sophistication of sports equipment used for more traditional recreational activities. This article reviews the injury patterns associated with in-line skates and skateboards, and analyzes the current status of protective equipment and equipment standards for these recreations.
Investigation of Impulsively-Started Flow Around Side-by-Side Circular Cylinders: Application of Particle Image Velocimetry
Authors: Sumner David , Price Stuart J. , Païdoussis Michael P.
Published: March 2022

The impulsively-started flow field for two and three circular cylinders of equal diameter arranged side-by-side has been investigated using particle image velocimetry (PIV), over a transverse pitch ratio range of T/D = 1.0 to 3.0, and for Reynolds numbers from Re = 1500 to 3000. The PIV technique was used to obtain a time history of the instantaneous in-plane vorticity field from the moment of impulsive start, from which the development of the flow was studied. Measurements of vortex strength and vortex position relative to the cylinders were obtained from these data. Two and three cylinder configurations of T/D = 1.0 were found to exhibit a cursory degree of similarity to a single, isolated impulsively-started circular cylinder. Side-by-side configurations of T/D > 1.0 were dominated by the strong gap flow(s) between the cylinders, the vortices generated alongside the gap flow(s), and the formation of a single counter-rotating vortex pair in the far-wake.
Estimation of an Improved Technique for Measuring a Near Wake Flow Field of a Bluff Body With a Parallel Triple-Wire Probe
Authors: Waka R. , Suzuki T. , Ochiai Y. , Watanabe T.
Published: March 2022

An improved technique using a hot-wire probe is proposed in order to obtain a more reliable velocity vector field which is less strongly influenced by the prong wake of the hot-wire probe.

In the present experiment, a parallel triple hot-wire probe was used and the velocity vectors were determined by a phase-averaging technique and the general response equations. The hot-wire probe was set not only parallel to (conventional technique) but also obliquely to the coming flow direction (improved technique). The improved technique was applied to the near wake flow field of a two-dimensional square-section cylinder.

As a result of the experiment, it was confirmed that the improved technique proposed here was useful for improving the experimental reliability for the velocity vector field of the square cylinder, except for the base region, compared with that measured by the conventional technique.
Flow-Induced Vibration of a Tube Array in the Inlet Region of a High Performance Steam Generator: Part 2 — Unstable Vibration and Chaos
Authors: Iwase Toshihiko , Sunami Takeshi , Matsutani Kazuhiko , Nakamura Tomomichi , Mureithi Njuki W. , Tsuge Ayao , Kasahara Jiro , Tomomatsu Ken-ichi , Takaba Osamu
Published: March 2022

The vibration of a tube array in the entrance region of a high performance steam generator, which is caused by the flow of the coolant fluid, has been shown to be random and having small amplitudes in Part 1 of this series. In this second part, the results of tests with modified tube boundary conditions are presented. Fluidelastic instability leads to chaotic vibration. All of the flexible tubes are at the extremities of the tube array, where the fluid-flow enters or exits the array. Even in this position the tube instability can be predicted by a Connors’ type criterion. Chaotic vibration occurs because the tubes have small gaps at the intermediate supports along the tube-span. A fractal dimensional analysis shows good coincidence with physical explanation of the phenomenon based on observation.
Broadband and Tonal Noise of Flow Excited Cavities
Authors: Bruggeman J. C. , Looijmans K. N. H. , Golliard J.
Published: March 2022

Noise generation by low Mach number flow over a cavity is investigated. Prediction models for broadband noise and for tonal noise are compared with experimental data. The prediction model for broadband noise is based on the wavenumber-frequency spectrum of pressure fluctuations under a turbulent boundary layer. In the prediction method for tonal noise, the self-sustained flow oscillations in the cavity opening are represented by periodic shedding of discrete vortices. The shape of the frequency spectrum of the broadband noise data agrees with the prediction but the amplitude of the data is 20–25 dB higher than the predicted values. The Strouhal numbers for tonal noise are well predicted by the present model. It is shown that self-sustained oscillations occur in the experiment for conditions where linearized stability theory predicts that shear layer oscillations will not grow.
Energy Flow Analysis of Flow-Excited Beams and Plates
Authors: Han F. , Bernhard R. J. , Mongeau L.
Published: March 2022

Two methods for calculating the power density input to structures excited by turbulent flow were developed and used to predict the average response of the structure. The input power density was calculated using the cross-spectral density of the random fluctuating pressure loading on the structure. The energy response of structures excited by distributed loading was obtained using the energy flow analysis method. Both methods for calculating the input power density and the method for calculating the energy density response were verified for beams and plates using classical modal analysis.
Non-Viscometric Flows of Viscoelastic Fluids in Round Tubes Driven by Transversal Boundary Waves
Authors: Siginer Dennis A. , Li Yunling
Published: March 2022

The unsteady transversal flow field in the tube flow of a memory integral fluid of order type driven by rotational boundary waves is investigated. A perturbation in terms of the amplitude of the sinusoidal boundary waves is used. Qualitative conclusions are independent of the explicit forms of the constitutive functions. Quantitative results are obtained by assuming Maxwell type of behavior for the latter. It is shown that transversal steady flows is a possibility if several rotational waves with frequencies in a certain ratio are imposed on the boundary. As a result helical steady flows may be possible in the longitudinal direction in a round tube. A parametrical study of the oscillating transversal field is presented for highly elastic and shear thinning liquids.
Active Control of Cantilevered Pipes Conveying Fluid With Constraints on Input Energy
Authors: Doki Hitoshi , Hiramoto Kazuhiko , Skelton Robert E.
Published: March 2022

This paper deals with the stabilization of flutter phenomena of cantilevered pipes conveying fluid with constraints on input energy for control. The controller in this study is designed by using an algorithm which iteratively tunes the weighting matrix of the quadratic performance index in LQG problem. This controller design method takes the performance of the actuator into consideration. The theoretical and experimental results show that the effectiveness of the controller in stabilizing the flutter phenomena of cantilevered pipes conveying fluid varies according to the input variance constraints, i.e., the difference in the dynamic range of an actuator. Furthermore, the critical flow velocity at instability of the pipe can be estimated by the method stated in this paper, where the system loses its stability because of the restriction of control force produced by an actuator.
Evaluation of Fluidelastic Forces in Axial Flow With Simplified Computational Fluid Dynamics
Authors: Kichenin J.
Published: March 2022

The nuclear industry is demanding low cost methods to prevent flow induced vibrations, which are a major cause of wear and damage of components such as core control bars.

An original model to compute the fluidelastic forces in axial flow is introduced in order to predict flutter. To carry on the calculation, a modal shape displacement is assumed and the Navier-Stokes equations are linearized, simplified and solved assuming the superposition of two independent velocity fields:

• V→0(M) is the steady-state flow along the fixed body, computed with a turbulent k-ϵ model;

• u→(M,t) is the potential flow associated with the vibration in “still” fluid.

The case of an uniform annulus is treated first, then a step variation is considered and finally the approach is extended to any parallel flow configuration. This method enables to compute the added mass, damping and stiffness coefficients and the structure in-flow eigenvectors without new algorithm.

Comparisons with the works of Païdoussis (1973), Gibert (1988), Perotin and Granger (1992) are presented here. Some rigid body laboratory tests are discussed and a satisfactory agreement between the predicted damping coefficient, the flutter occurrence and the experimental results is achieved.
Analysis of Acoustic Resonant Vibration Having a Mutual Exciting Mechanism
Authors: Tanaka Hiroki , Matuzoe Jungo , Tanaka Kazuhiro , Shimizu Fumio
Published: March 2022

A duct containing a tube bundle undergoes acoustic resonant vibration. It is considered that the acoustic vibration is a kind of forced vibration by means of Karman vortex. However, it will be more reasonable to think that the vibration is a kind of mutual excited vibration, because fluid force excites sound pressure and the sound pressure also excite the fluid force. Equation of motion of sound pressure was derived from the mutual excited mechanism. Solution of the equation revealed that the imaginary part of the fluid dynamic force on the tube bundle supply the energy of sound and on the other hand, radiation of sound consumes the energy. By comparing the supplying and consuming energies, it became possible to calculate a boundary where acoustic resonant vibration will occur.
Damping of Tube Bundles in Two-Phase Air-Water Cross-Flow
Authors: Baj F. , Payen T. , de Langre E.
Published: March 2022

The investigation of damping in two-phase air-water cross-flow is discussed in this paper. A design guideline had been proposed by Pettigrew et al. (1994). In this paper, new set of air-water experiments is analysed. It is observed that the above guideline is too conservative and that flow velocity needs to be used to account for the scatter of data. Then, a new reduction of data is proposed and dependence of fluid damping with reduced velocity is investigated.
Flow-Induced Oscillations of a Butterfly-Valve: Prediction of the Frequency Behaviour
Authors: Hirt Felix , Iten Roger , Ziada Samir
Published: March 2022

The present valve design consists of two leaflets that are freely movable around a pivot and arranged within an orifice. At the open position the leaflets form a slight divergence angle. The flow patterns at low Reynolds number generated by such a design are associated with leading-edge stall and vortex-shedding from the leaflets. The present investigation is directed to a better understanding of the nature of this flow. In particular the effect of leading-edge stall on the angular oscillation behaviour of a single leaflet is of interest. For this purpose the leaflet momentum has been described in terms of a simple nonlinear hydrodynamic model which takes into account the direction of the gravitational vector. Based on that model the frequency behaviour was investigated numerically in parameter space. The effect of the flow speed on the oscillatory leaflet motion is treated as quasi-steady, that means for small Strouhal numbers Sh ≪ 1. The preliminary results reveal a strong dependence of the oscillation frequency on the amplitude and on the direction of the gravitational field vector. On the basis of a perturbation analysis an expression relating frequency and amplitude was found.
Experimental Characterization of Centrifugal Pumps as an Acoustic Source at the Blade-Passing Frequency
Authors: Zbroja Stan , Rzentkowski Grzegorz (Greg)
Published: March 2022

In this paper, we formulate an experimental method to examine the pump acoustic characteristics and report the test data. First, we assess the resonance effects in the test loop by calculating the acoustic impedance and reflection coefficient at the pump ports from local pressure field measurements. Next, we decompose the measured signal into the components associated with pump action and loop acoustics with the use of a simple pump model based on linear superposition of pressure wave transmission and excitation.

We apply this technique to examine the acoustics of a single-stage, double-volute centrifugal pump. We estimate the strength of source variables at the blade-passing frequency and establish the pump characteristics as an acoustic source. The results indicate that the source variables are nearly free of acoustic resonance effects in the test loop. The pump characteristics, however, depend on the location of pump ports and loop acoustics; that is, a given pump may act either as a pressure or as a velocity source.
Serial and Parallel Fast-Floquet Analyses in Rotorcraft Aeroelasticity
Authors: Subramanian S. , Venkataratnam S. , Gaonkar G. H.
Published: March 2022

Rotorcraft stability investigation involves a nonlinear trim analysis for the control inputs and periodic responses, and, as a follow-up, a linearized stability analysis for the Floquet transition matrix (FTM), and its eigenvalues and eigenvectors. The trim analysis is based on a shooting method with damped Newton iteration, which gives the FTM as a byproduct, and the eigenanalysis on the QR method; the corresponding trim and stability analyses are collectively referred to as the Floquet analysis. A rotor with Q blades that are identical and equally spaced has Q planes of symmetry. Exploiting this symmetry, the fast-Floquet analysis, in principle, reduces the run time and frequency indeterminacy of the conventional Floquet analysis by a factor of Q. It is implemented on serial computers and on all three types of mainstream parallel-computing hardware: SIMD and MIMD computers, and a distributed computing system of networked workstations; large models with hundreds of states are treated. A comprehensive database is presented on computational reliability such as the eigenvalue condition number and on parallel performance such as the speedup and efficiency, which show, respectively, how fast a job can be completed with a set of processors and how well their idle times are minimized. Despite the Q-fold reduction, the serial run time is excessive and grows between quadratically and cubically with the number of states. By contrast, the parallel run time can be reduced dramatically and its growth can be controlled by a judicious combination of speedup and efficiency. Moreover, the parallel implementation on a distributed computing system is as routine as the serial implementation.
Modeling and Aeroelasticity of Advanced Aircraft Wings Carrying External Stores
Authors: Gern Frank H. , Librescu Liviu
Published: March 2022

In order to study the effects of wing mounted stores upon the aeroelasticity of advanced aircraft wings, a comprehensive structural model has been developed. The wing structure is idealized as a laminated composite plate thus leading to the concept of a shear deformable plate-beam model. Free body motions at the wing root are induced by the motion of the airframe in pitching, plunging, and rolling. Non-classical effects like warping inhibition and transverse shear flexibility are included in the structural model. The relevant equations of motion as well as the appropriate boundary conditions are obtained via Hamilton’s variational principle and application of generalized function theory in order to exactly consider the spanwise location and properties of the attached stores. Numerical predictions for divergence behavior and static aeroelastic response of the system using extended Galerkin’s Method are supplied.
A Three-Dimensional Computer Simulation for Interactive Adjustment of Multiple Axes of Motion for the Upper Extremity
Authors: Pickard Julie M. , Buford William L. , Elder Karin W. , Patterson Rita M.
Published: March 2022

With the advent of high performance computer graphic workstations over the last decade, kinematic modeling of the human musculoskeletal system is developing rapidly. Previous kinematic models have been developed but their workstations and/or software have become outdated. Buford and Thompson (1987) developed an interactive kinematic simulation, but it is no longer utilizable because the software was developed on the outdated Evans and Sutherland (E&S) PS300 system. Lin, et. al. (1995) developed a three-dimensional kinematic simulation using PHIGS programming software. Since PHIGS is no longer the accepted standard for graphics software, this simulation has lost its portability.
Optimal Actuator Placement in Hyperthermia: A Reduced-Order Modeling Approach
Authors: Mattingly M. , Roemer R. B. , Devasia S.
Published: March 2022

Studies have shown a positive correlation between the effective temperature maintained inside a cancerous tumor during hyperthermia treatments and the response rate of that tumor to subsequent radiation therapy (see, for example, [1]). In addition, effective temperature control is crucial to avoid the premature abortion of hyperthermia treatments from patient discomfort due to overheating of the normal tissue surrounding these tumors. Hence, there is a need to optimally heat tumors and surrounding tissue — this is significantly affected by the choice of actuator placement and input powers. In this work, we show how the extended balanced realization model reduction approach [2] can be employed to efficiently determine the optimal scan path for a given hyperthermia treatment.
Preconditioning Does Not Reset the Strain History of Uniaxially Tested, Porcine Aortic Valve Tissues
Authors: Vesely Ivan , Brewer Amy R.
Published: March 2022

Heart valve leaflets are considered to be viscoelastic, much like most biological materials. When these materials are tested both uniaxially and biaxially, a so-called “preconditioning” effect is observed. Upon repetitive loading to a constant load, sucessive load/elongation plots migrate in the positive strain direction. After about 10 cycles, successive load/elongation plots are repeatable, both in terms of the energy dissipated as well as the exact elongation achieved at a given load. This type of preconditioning needs to be done prior to any data acquisition or analysis, since the initial curves are not reproducible from test to test. In other words, unless the tissue is preconditioned first, it will not generate the same load at the same strain.
Relationship of Flow Disturbances in Stented Vessels to Compliance Mismatch
Authors: Berry Joel L. , Moore James E. , Barnes Ralph W.
Published: March 2022

The mechanical conditions created by vascular stents may play a role in restenosis. Restenosis occurs due to the accumulation of blood-borne materials and the reaction of the wall to the presence of the stent. It has been previously demonstrated [1] that the flow patterns created by the placement of a rigid stent into a compliant blood vessel are highly complex, featuring large vortex formations. It was hypothesized that the abrupt changes in compliance at the proximal and distal stent/artery junctions created pressure wave reflections that led to the vortices. The purpose of this study was to test whether a smooth transition in compliance between stented and unstented vessel would minimize pressure wave reflections and reduce the complexity of fluid flow disturbances. For this purpose, a new stent design was conceived and tested that featured compliance transition zones at the proximal and distal ends. The design is called a compliance matching stent (CMS).
Conservation of Cardiovascular Input Energy With a Rhythmically Contracting Aorta
Authors: Souza-Campos Flavio B. , Schoephoerster Richard T.
Published: March 2022

Besides conveying blood, the aorta has a capacitive function, decreasing peak cardiac work load during systole and assuring sustained peripheric sanguine irrigation throughout the cardiac cycle.
Flow Phenomena in the Human Aortic Root and Entrance Region of Coronary Arteries During Diastole
Authors: Ilegbusi Olusegun J. , Hu Zhenjun , Stone Peter H. , Feldman Charles L.
Published: March 2022

The potential role of hemodynamics on atherogenesis and lesion progression in coronary arteries has been widely studied both experimentally and numerically. Clinical and postmortem examinations have provided valuable insight on the location of these lesions and the impact of flow disturbance and wall shear stress on their development. The determination of the exact conditions at the entrance of the coronary arteries as required for accurate numerical simulation of intracoronary flow pattern is difficult due to the inherent flow unsteadiness and the complexity of the ostium geometry. Thus, most previous theoretical analyses have often assumed uniform or parabolic spatial distribution of the entrance velocity. Such assumption severely limits the scope of validity of these studies because the strong curvature of the ostium and the relatively short length of the epicardial coronary artery do not allow for adequate flow development upstream of the coronary branches or regions of curvature where lesions occur.

This problem is further exacerbated by the non-uniqueness of the location of the ostium. It has been shown that the rate of blood flow in the coronary artery depends on the ostium location which in turn affects the flow characteristics, wall shear stress distribution and lesion proliferation on the arterial wall.

The objective of this paper is to predict the entrance velocities in human coronary arteries through a numerical model of flow in the aortic root. Specifically, we perform a detailed investigation of the flow pattern in a model human aortic root with two adjoining arteries. At this initial phase of model development, we consider the flow behavior only at diastole, the period of maximum coronary artery flow. A range of ostium curvatures and locations and coronary flow Reynolds numbers are considered. Emphasis is placed on characterizing the flow separation and recirculation resulting from the complex geometry of the aortic root-ostium assembly. The conservation equations governing the transport of mass and momentum are written in curvilinear coordinate system and solved using a fully-implicit finite domain numerical scheme. The predictions are checked for numerical accuracy through systematic grid refinement. The predicted flow pattern at the entrance of the coronary artery is subsequently used as an input for calculation of flow and wall shear stress characteristics in stenosed coronary artery curvatures and bifurcations. The predictions are compared with the experimental data and existing numerical results where available.
Dependence of Kinetic Rates on Receptor’s Membrane Anchor
Authors: Chesla Scott E. , Zhu Cheng
Published: March 2022

Kinetic rates of adhesive receptors for ligands are essential to a wide variety of biological phenomena. Only very recently has measuring kinetics of surface-linked molecules become possible. Just a handful of data exit in the literature [1–3].
Wrist Kinematics
Authors: Patterson R. M. , Nicodemus C. L. , Viegas S. F. , Elder K. W.
Published: March 2022

Much work has been done related to the qualitative osseous anatomy of the wrist yet there are still very few references for its quantitative geometric, biomechanic, or kinematic characteristics.1–3 Because of the structural complexity and morphological variations of the wrist, a reference database of normal anatomy and kinematics would provide valuable reference information which will facilitate diagnosis and treatment of various injuries and diseases.
Electrical Signal Transmission in a Bone Cell Network: The Influence of a Discrete Gap Junction
Authors: Zhang Dajun , Weinbaum Sheldon , Cowin Stephen C.
Published: March 2022

Live bone is a very dynamic tissue under constant remodeling in response to the mechanical loading it sustains. However, the exact load-sensing mechanism of bone tissue is not yet clear. Recent studies suggest that the electrical aspect of bone physiology, especially the streaming potential, may play an important role in relaying the mechanical signal to the effector bone cells in bone remodeling [1] [2] [3]. In this paper, we use cable theory to calculate the intracellular potential and current in the bone cell network induced by the extracellular strain generated streaming potentials (SGPs). As an extension to our earlier paper on this subject, Zhang et al. [5], we focus our attention on the following five aspects:

<1> influence of the axisymmetric, cylindrical geometry of the osteon on the SGP calculation;

<2> influence of one discrete gap junction in a cellular cable;

<3> influence of a range of the membrane resistance (hence the membrane time constant);

<4> influence of the extracellular glycocalyx (GAG) fiber matrix in the lacunae-canaliculi space on the SGP calculation;

<5> influence of a range of the membrane leakage area of a resting osteoblast as one end of the cellular cable.
Using a Fabric Flexible Composite Theory to Characterize the Soft Tissues
Authors: Taban Faruk , Luo Shen-Yi
Published: March 2022

The objective of this work is to propose an analytical model, which is based on a fabric flexible composite theory, to characterize soft tissues (such as heart muscle, skin, lung, blood vessel, etc.). The bi-axial mechanical behaviors of the soft tissues have been studied by many researchers. A common approach is to propose a set of constitutive equations, then use data regression method to obtain input values from both simple and bi-axial test results. This usually gives a good description of the stress-strain behavior for the particular material but gives no physical meaning of these input values obtained from the mathematical curve fittings. Pao et al. (1980) suggested that the mechanical properties of the fiber bundles must be predicted first to compute the stresses. In this proposed model, a soft tissue is considered as an orthogonal composite element containing wavy fibers in a soft incompressible matrix (Luo and Chou, 1990).
A Biomechanical Comparison Between Modern Anterior Versus Posterior Plate Fixation of Unstable Cervical Spine Injuries
Authors: Lim Tae-Hong , An Howard S. , Koh Young Do , McGrady Linda M.
Published: March 2022

Unstable cervical spine injuries include flexion-distraction injuries with unilateral or bilateral facet dislocations and burst fracture of the vertebral body. These unstable injuries have been treated in various ways. For instance, various posterior fixation methods have been available, and particularly plating with lateral mass screws was proved to provide a rigid fixation. However, most cervical decompressions need to be performed anteriorly because the majority of compression is caused by either vertebral body retro-pulsion or herniated disc material (anterior structure). Anterior plating technique was recently introduced and employed for the surgical treatment of unstable injuries. Anterior plating is thought to offer an acceptable stability through a single surgical approach, but additional posterior fixation is frequently recommend to achieve a sufficient stability. There is a paucity of data on a direct biomechanical comparison of the stiffness provided by modern anterior, posterior, or combined plate-screw fixation in a human cadaveric cervical spine model. The purpose of this study was to compare the biomechanical characteristics of anterior vs posterior plating constructs and to evaluate the stiffness of a combined anterior-posterior fixation construct in a clinically simulated flexion-distraction injury and burst fracture models of the cervical spine.
An EMG-Driven Model of Trunk During Complex Isometric Exertions in Upright Posture
Authors: Sheikhzadeh Ali , Parnianpour Mohamad , Nordin Margareta
Published: March 2022

The EMG-driven models of trunk have been used to predict force generated by the trunk muscles and thereby risk of injury by estimating the net joint reaction forces. These models are based on the assumption that tensile force generated in a muscle is related to the normalized EMG and adopted cross-sectional area of the muscle. The EMG-force relationship adopted by these models assumed a linear relationship with zero intercept. However, no experimental justification exists to explain the zero intercept in the EMG-driven models. The aim of this study was to test the hypothesis that the results of EMG-driven models will be affected significantly by the assumptions made with respect to the EMG-force relationship of the trunk muscles.
Response of the Lumbar Spine in Large Compression Loads: Effect of Load Distribution in Neutral Postures
Authors: Shirazi-Adl A. , Parnianpour M.
Published: March 2022

During various daily activities, the gravity as well as external compression loads are transmitted to the pelvis via the lumbar spine. A major portion of this load, accounting for the upper body, is applied on the L1 while the remaining portion is transferred directly through lower lumbar vertebrae L2 to L5. This latter accounts for the gravity and local muscle activities at the lumbar level. The more physiological application of the load distributed at all vertebral levels and not concentrated only at the most proximal one has been demonstrated to markedly stabilize the spine in axial compression [1,2]. This study aims to compute the detailed mechanics of the lumbar spine in neutral posture under 2800 N axial compression applied either at the L1 only or distributed at all levels with the proportion of 90% or 80% of the load at the L1 and the remaining part applied evenly among the other L2-L5 levels.
Carbon Based Prosthetic Devices
Authors: Devlin D. , Carroll D. , Barbero R. , Klawitter J. , Strzepa P. , Ogilive W.
Published: March 2022

The medical profession has a need for improved orthopedic devices and biomaterials. The replacement of knee and hip joints with metallic prosthetic devices has provided mobility to many elderly patients suffering from bone diseases. Unfortunately, metal prostheses, anchored with methyl methacrylate cement, have a useful life of 7 to 10 years. Bond failure and wear necessitates an entire replacement of the prosthesis. Bone resorption due to the presence of the implant limits the number of implant operations to two per patient. As a consequence joint replacement is restricted to patients over age 55. A definite need exists for a new material system for extending the expected life of these prosthetic devices for younger patients. The long term objective of this research is to greatly extend the service life of prosthetic devices, specifically artificial joints. A materials system approach is being employed to accomplish this objective. The two specific materials technologies being integrated in this proposed study are carbon/carbon composites and diamond-like carbon (DLC) coatings.
Tendon Force Estimates Following Hand Surgery
Authors: Peña Edward , Thompson David E. , Evans Roslyn B.
Published: March 2022

The need for quantitative methods for assessment of tendon forces following tendon reconstructive surgery arises because of the side effects of current post-operative therapy. The classical therapy over the past 50 years has been to insulate the hand from potential injury in a cradle of bandages. This method was originally introduced because movement of the hand following surgery was felt to result in failures of the repaired tendons which have a very limited strength. The subsequent stiffening of the joints, and reduction in the gliding action of tendons is exacerbated by the swelling and inflammatory processes resulting from the surgery. In recent years, a new post-surgical therapy has been introduced that dramatically improves the range of motion and reduces the time to clinical release of the patient. This procedure is similar to that used prior to the current conservative therapy, but better analytical methods have allowed restrictions to be imposed on the active motion of the hand following surgery.

The force analysis that has led to new guidelines for post-surgical hand therapy for flexor tendons is presented here. A graphical user interface is also presented which allows the user to study various external force loadings and obtain rapid feedback on the resulting tendon forces at user-defined joint angles. This is shown in Figure 1.
Framework Design for an Orofacial Implant-Supported Prosthesis
Authors: Kasra Mehran , Anderson James D.
Published: March 2022

Loss of the entire midface leaves few options available for support of the dentition. Total loss of the maxilla bilaterally means that none of the traditional support areas are even partially useful. Surgical reconstruction of the midface is aggressive, and yet problems of support and retention for a dental prosthesis, as well as the facial prosthesis, remain. Osseointegrated implants can provide support and retention utilizing the remaining bones, but the distribution of occlusal forces becomes a concern, given their unfavourable location relative to the opposing dentition. Considerable attention has been given to framework design for intraoral implant-supported prostheses (1) but designs for extraoral framework typically have not been engineered with a view to controlling forces on the individual implants. This work describes the design procedure of such an extraoral framework which was fabricated for an individual. To minimize the possibility of unintentional overloads, consideration of the forces on each of the implants was prominent in design planning.
Effects of Acetabular Component Lip Design on Dislocation Resistance in THA
Authors: Scifert Christopher F. , Brown Thomas D. , Pedersen Douglas R. , Callaghan John J.
Published: March 2022

Next to aseptic loosening, recurrent dislocation is the second leading cause of failure in total hip arthroplasty [1]. Impingement of the femoral component neck on the acetabular cup is a frequent mechanism. Dislocation rates range from 2–11% in primary THA surgeries, and up to 25% or more in revisions [2]. Despite this high incidence, little is known about contributory component design factors. A finite element (FE) model has therefore been developed to systematically study impingement and dislocation resistance.
The Effect of Femoral Component Rotation on the Stresses in an UHMWPE Patellar Prosthesis: A Finite Element Study
Authors: Petrella Anthony J. , Rubash Harry E. , Miller Mark C.
Published: March 2022

Complications associated with the patellofemoral joint remain among the most common causes for revision of total knee replacements [1]. Excessive patellar tilt and medial-lateral shift are signs of poor patellar tracking and are frequently associated with patellar subluxation. Experimental studies have shown that external rotation of the femoral component improves patellar tracking and the distribution of patellofemoral contact forces [2,3]. The objective of this study was to develop a finite element model to study the influence of femoral component external rotation on patellar kinematics and contact stresses under physiologic loading.
Alternative Bearing Surfaces for Arthroplasty
Authors: Graham Robin M. , LaBerge Martine
Published: March 2022

Elastomeric materials have been suggested for use in total joint arthroplasty as an alternative to ultra high molecular weight polyethylene (UHMWPE).1–2 As a bearing material operating under mixed lubrication regimes, UHMWPE is subject to wear. Wear particles cause an adverse tissue reaction eventually resulting in loosening of the prosthesis. The modulus of elasticity of the UHMWPE does not allow sufficient deformation of asperities which would increase the film thickness between the bearing surfaces and prevent wear. Elastomers, however, can deform under pressure and enhance lubrication by the formation of a fluid film through elastohydrodynamic and micro-elastohydrodynamic lubrication.3 However, elastomeric coatings are subject to fatigue and debonding from their rigid substrates. To promote fluid film lubrication and prevent failure associated with the use of soft elastomeric bearings, a “true cushion” bearing was designed consisting of a soft elastomer sandwiched between a thin rigid coating and a thick rigid substrate of similar chemistry. This study was aimed at characterizing the frictional behavior of this construct in a lubricated environment as compared to UHMWPE and a non-coated soft elastomeric bearing.
Relations Between Trabecular Bone Properties and MRI Relaxation Times
Authors: Hogan H. , Lin C. , Ambrose C. , Evans H. , Harrigan T. , Shackelford L. , LeBlanc A.
Published: March 2022

Increasing attention has been given in recent years to using magnetic resonance imaging (MRI) to assess skeletal condition. This method of imaging is sensitive to the marrow/bone interface and is therefore attractive for characterizing trabecular bone, which is the bone tissue most seriously affected by osteoporosis or bone loss due to disuse or weightlessness. With proper processing and analysis, the information gained from MRI scans has the potential to provide measures of trabecular bone architecture rather than just bulk density or mass, but the extent to which this is true has not been definitively documented to date. Recent studies by Chung et al. (1993) and Jergas et al. (1995) have examined the relationships among mechanical properties and MRI signals, with encouraging results. More specifically, the effective transverse relaxation time T2* and its reciprocal (transverse relaxation rate) have been the main parameters used in previous studies because T2* is believed to be an indicator to some degree of trabecular architectural features. The present study addressed these same questions but a different protocol for imaging and specimen preparation has been used, and a larger number of specimens were tested.
Degradation of Poly(L-Lactic Acid) Monofilaments for Experimental Intravascular Stent Designs
Authors: Nelson Kevin D. , Phansalkar Anagha R. , Romero Andres A. , Ye Yun-Wei , Eberhart Robert C. , Landau Charles , Meidell Robert S.
Published: March 2022

Metal stents are placed in coronary arteries as an adjunct to balloon angioplasty with increasing frequency. The long term follow up to these clinical stenting procedures in currently three years. There is no published experience for longer periods and many concerns have been raised, including metal fatigue, stress-enhanced corrosion and stress-enhanced damage to adjacent healthy tissue. As a potential improvement to current metal stent designs, we are developing more compliant polymeric stents, employing bioresorbable materials.
Effect of Chemical Fixation on the Fiber Kinematics of Bovine Pericardium
Authors: Billiar Kristen L. , Sacks Michael S.
Published: March 2022

Microstructural modeling of chemically treated bovine pericardium (BP), a popular material for cardiovascular bioprostheses, requires knowledge of the initial collagen fiber angular distribution and fiber kinematics.1 In a previous study, utilizing combined small angle light scattering (SALS) and biaxial stretch, we found that the collagen fibers in fresh BP reorient towards the direction of stretch to a greater extent than predicted by an affine transformation model.2
Haptic Perception of Simulated Surface Textures via Vibratory and Force Feedback Displays
Authors: Weisenberger Janet M. , Krier Michael J.
Published: March 2022

In human sensing of surface texture, both force feedback from surface features and vibratory feedback from repeated stimulation of tactile mechanoreceptors may be involved. The present study investigated the effectiveness of two haptic interfaces, one providing force feedback to the fingertip, and the other providing vibratory feedback to the fingertip, in conveying aspects of surface texture. Results for the vibratory display indicated that subjects could differentiate surfaces that differed in vibratory frequency, intensity, and spatial density. For the force display, we obtained minimum values for differences in spatial frequency and amplitude that permitted discrimination between pairs of surfaces. Implications for the simulation of real surfaces are discussed.