bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chondrocyte Translocation and Orientation to Applied DC Electric Fields
Authors: Mauck Robert L. , Chao Pen-hsiu G. , Gilbert Beth , Valhmu Wilmot B. , Hung Clark T. 
Published: December 2021

Abstract
Chemical and mechanical stimuli are known to cause directed movement in a number of different cell types. Less prominently studied, direct current (DC) electric fields are known to induce a similar response. In this study, we report on DC electric field-induced chondrocyte migration and re-orientation. Galvanotaxis and galvanotropism, migration and shape change in response to applied DC electric fields, respectively, have been demonstrated in many cells. For instance, field strengths of 1–10 V/cm have been reported to induce migration in keratinocytes. corneal epithelial cells, bone cells, fibroblasts and neural cells [1,7,8,11]. Recently, we have demonstrated for the first time that chondrocytes exhibit a galvanotactic response, realigning and migrating in response to applied DC electric fields (6 V/cm) [6]. In cartilage, chondrocytes may see electric fields associated with streaming potentials estimated to be up to 15 V/cm with current densities of up to 0.1A/cm2 [2]. The aim of this study was to explore basic science aspects of directed cell migration under applied DC electric fields and to investigate the potential application of this phenomena for tissue engineering, healing and repair of cartilage. The ability to direct cell growth and function will have significant implications on the bioengineering of replacement tissues.
Development of an Experimental Procedure for Pre-Clinical Testing of Cemented Hip Replacements
Authors: Maher Suzanne A. , Prendergast Patrick J. , Waide D. Victor , Reid Alan J. , Lyons C. Garrett 
Published: December 2021

Abstract
Current standards for testing cemented femoral hip stems involve potting the distal third of the stem and applying a cyclic load, see ISO 7206-8. 1995(E). However, this procedure does not test implants for the most prevalent mode of failure — loosening of the prosthesis from the host bone (Malchau et al., 1993). To quantify the expected longevity of implants in a pre-clinical test, a protocol that establishes the rate of loosening of a prosthesis must be developed.
Using Radiostercophotogrammetry (RSA), Karrholm et al. (1994) have correlated migration of more than 1 mm within two years of implantation with early loosening of the implant. Therefore, by quantifying the migration of a prosthesis in a laboratory test for the equivalent of two years post implantation, its risk of loosening in vivo can be assessed. In the past, the motion of cemented implants in one direction has been quantified (Manley et al., 1987); whilst other researchers have performed a more complete analysis of the motion of prostheses, but for a limited number of loading cycles (e.g. Schneider et al., 1989). In most of these studies, prosthesis insertions were performed by surgeons. Not only does this introduce subjectivity into the pre-clinical test, but in the case of cemented replacements, variations in stem orientation and cementing pressures will occur. This paper presents the design and initial validation of procedures which may be used for pre-clinical testing of cemented hip stems.
Investigation of Performance of a Femoral Implant With a Plug Using Finite Element Analysis
Authors: Chu Taiming , Carstarphen Deanna Y. 
Published: December 2021

Abstract
A Finite Element Analysis was performed on the critical section of a titanium alloy femoral implant coupled with a cobalt-chromium Dall-Miles Cable Grip System (DMCGS). The critical section of the implant is defined at the hole where the wires of the DMCGS are threaded. Two models were generated for the analysis. The first model consisted of the critical section with a cobalt-chromium plug filled in at the hole. The second model consisted of the critical section without the plug in the hole. The models used in the study were based on a design developed by Howmedica Incorporated (called the “head-neck replacement”). One static simulation was performed on each model. This simulation represented the early stance phase of normal walking. The wires used in the simulations were pre-tensioned. The preliminary results of the analysis showed that the stresses in the model with the added plug were lower than those in the model without the plug. This indicated that a plug added to a femoral implant adjoined with the Dall-Miles Cable Grip System reduces the stress concentrations at the hole. Furthermore, the results of the study will provide insight into the modifications on design of femoral implants. This may well lead to an improvement in implant performance and better aid in the restoration of hip function for arthritic patients.
Measurement of Osteocyte Deformation Resulting From Fluid Flow Induced Shear Stress
Authors: Nicolella Daniel P. , Sprague Eugene , Bonewald Lynda 
Published: December 2021

Abstract
It has been shown that bone cells are more responsive to fluid flow induced shear stress as compared to applied substrate strain (Owan, et al., 1997, Smalt, et al., 1997). Using novel micromechanical analysis techniques, we have measured individual cell strains resulting from 10 minutes of continuous fluid flow at a flow rate that produces a shear stress of 15 dyne/cm2. Individual cell strains varied widely from less than 1.0% to over 25% strain within the same group of cells. The increased sensitivity of cells to fluid flow induced shear stress may be attributed to much greater cellular deformations resulting from fluid flow induced sheer stress.
Role of Vertebral Shell and Endplate Modulus on Whole Vertebral Body Stiffness
Authors: Liebschner Michael A. K. , Kopperdahl David L. , Keaveny Tony M. 
Published: December 2021

Abstract
The contribution of the cortical shell and endplate to the stiffness and strength of the vertebral body is not well understood. However, several studies have suggested that the cortical shell plays an important role in the fracture strength of the whole vertebral body as bone is progressively lost from the centrum due to aging and osteoporosis (Eastell 1991, Faulkner 1991, Kurowski 1986. Silva 1997). Silva et al. (1994) concluded that prediction of cortical bone geometry using computed tomography (CT) based measurements is subject to considerable uncertainly caused by image distortion and the low ratio of image resolution of 0.25 mm/pixel to cortical shell thickness (0.09–0.86 mm). Thus, in development of CT-based models of the vertebral body, particular attention should be paid to the details of shell modeling.
Transversely Isotropic Model of Osteonal Cortical Bone: Contribution of Haversian and Resorptive Porosity
Authors: Dong X. Neil , Huang Y. Young , Guo X. Edward 
Published: December 2021

Abstract
Age related changes in porosity of cortical bone have been previously reported. The cortical porosity increases with age in both men and women, from 4.6% in men and 4% in women at age 40 to 10% and more at age 80 (Laval-Jeantet et al., 1983). The porosity is defined as the percentage of cortical bone occupied by vascular and resorption cavities. There are a few quantitative data regarding the influences of Haversian canal and resorption space on porosity. Age related increases in Haversian canal size and Haversian canal number contribute to the increasing porosity of cortical bone for the elderly men and women (Thompson, 1980; Nyssen-behets et al., 1997). The number of osteoclastic resorption space is also greater in the old men than in the young men (Nyssen-Behets et al., 1997).
Effects of Stenosis Severity and Balloon Characteristics on Stresses in Balloon Angioplasty — A FEM Study
Authors: Gourisankaran Vijay 
Published: December 2021

Abstract
Studies of stresses in an artery under normal physiological pressure loads have been made to gain insight into the possible causes of plaque rupture and progression of atherosclerosis. This study addresses the effects of stenosis severity, and balloon stiffness on the peak stresses experienced in the system during angioplasty. It is proposed that the effectiveness and therefore success of an angioplasty procedure can be measured by the non-propensity for restenosis to occur, and the absence of high stresses in the diseased artery at peak balloon dilation pressures. The models used in this study use nonlinear material properties of the arterial wall and the balloon, large deformations during the angioplasty procedure and contact between the arterial wall and the balloon.
Virtual Position Control During Contact Tasks
Authors: English Chad E. , Russell Donald L. 
Published: December 2021

Abstract
It is well known that human limbs have spring-like behaviour that has been attributed to both compliance of the muscles and reflex action [Hogan, 1985; Mussa-Ivaldi et al., 1985]. These mechanics are the premise behind the Equilibrium Point (EP) Hypothesis for motor control [Bizzi et al., 1992; Shadmehr et al., 1993; Won & Hogan, 1995]. Essentially, EP theory suggests that muscles are activated such that they define a unique position of the limb in the workspace, called the virtual point, where there are no net joint moments [Bizzi et al., 1992]. (Some refer to this as the equilibrium point, but that notation can be confused with a contact equilibrium.)
If an amputee using a prosthetic limb uses the EP control technique naturally, it is necessary for the prosthesis to included mechanical properties sufficiently similar to those of a natural limb to produces similar results. The necessary mechanics, and limitations of not providing them, are the bulk of the authors’ current research. The current work examines the control of contact forces.
A variety of studies have examined virtual paths for unconstrained motions [Flash, 1987; Lan & Crago, 1994]. Others have implemented a predetermined virtual point path in an artificial manipulator during contact tasks [Hogan, 1987]. However, little information is available on the virtual point path required to produce desired contact properties. This study analytically and numerical investigates the virtual point path required to vary contact force without producing a motion of the limb along the surface.
On the Decoupling of the Passive and Active Components of Muscle Force
Authors: Karakostas Tasos E. , Parnianpour Mohamad , Berme Necip , Pease William S. , Quesada Peter M. , Simon Sheldon R. 
Published: December 2021

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

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

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

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

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

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

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

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

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

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