bluuebunny/crossref_metadata_2025_split huggingface dataset:
Isometric Co-Contractions of the Quadriceps and Hamstrings in Intact and PCL-Deficient Knees
Authors: Yang Hongzhi , Li Yi-Chun , Hefzy Mohamed Samir 
Published: December 2021

Abstract
The exercises to strengthen the muscles around the knee are designed to improve its stability. During these exercises, co-contraction of the hamstrings occur depending on the level of quadriceps contraction. The purpose of this study is to develop a three-dimensional knee model that includes tibia, femur and patella and allows to predict knee response due to quadriceps and hamstrings co-contractions. As an application, results quantifying the changes in knee response are obtained following a simulated posterior cruciate ligament (PCL) injury. This is motivated by the continuing debate whether surgical repair is the method of choice for individuals with such an injury. It has been reported that following a knee injury, a large number of patients with PCL deficiency develop significant disability with Osteoarthritis (OA). The conditions tested simulate the straight-leg-raise exercise, during which the quadriceps muscles contract isometrically along with hamstrings co-contractions.
A Strain Energy Function for the Annulus Fibrosus Specified Using Biaxial Experimental Data
Authors: Bass Elisa C. , Lotz Jeffrey C. 
Published: December 2021

Abstract
The mechanical behavior of the annulus fibrosus has typically been characterized through the use of uniaxial tests. In contrast, its in vivo constraints are multiaxial and likely result in a mechanical response very different from that observed to date in vitro. The goal of this study was to test the annulus in biaxial tension and use these data to determine an elastic strain energy function for the annulus. Our results demonstrate that the mechanical response of the annulus is dramatically influenced by a biaxial constraint, and that these experiments provide important data for the determination of the constitutive formulation for this strongly anisotropic and nonlinear tissue.
Senior Design Projects to Aid the Disabled at the University of Toledo: Community Outreach and Impact
Authors: Hefzy Mohamed Samir , Nemunaitis Gregory , Naganathan Nagi , Smallman Christine 
Published: December 2021

Abstract
This paper describes the community involvement and the impact that the Department of Mechanical, Industrial and Manufacturing Engineering (MIME) at the University of Toledo (UT) has accomplished during the past six years with its senior students in developing custom devices for physically disabled individuals within the Toledo community. These projects assist disabled individuals to better enjoy life and realize their maximum potential. These projects significantly enhance the education of student engineers through the experience of designing and building devices to meet a real need with feedback on how well the device satisfies that need.
Dynamic Functional Imaging of the Musculoskeletal System
Authors: Alexander Eugene J. , Andriacchi Thomas P. , Lang Philipp K. 
Published: December 2021

Abstract
It can be highly enlightening to integrate the 3D images of anatomic elements of specific subjects performing their activities of daily living: equations describing motions, forces, moments, cartilage contact points, muscle activations, ligament insertion point motion and many other functional events can be brought to life by animation in 3D. Understanding, teaching, and communicating results are all immediately enhanced by these techniques; we are currently working with clinicians on applying these techniques to our primary goals: functional evaluation, diagnosis, and treatment planning. This abstract discusses the techniques currently in development to generate these animations.
Experimental Measurement of Weightbearing After Ankle Replacement
Authors: Miller M. C. , Aitken S. G. , Petrella A. J. , Conti S. F. 
Published: December 2021

Abstract
Gait laboratory measurements on unilateral ankle replacement subjects were made at one year after surgery. The basic form of the vertical component of the ground reaction force on both the affected and unaffected sides retained the pattern typical of normal subjects, with an initial peak, an intermediate minimum, and a second peak. Statistical analysis using paired t-tests showed a significant difference only between the values of ground reation force at the second peak (p = 0.01).
Crack Branching Off an Interface Between Anisotropic Thin Strips
Authors: La Saponara Valeria , Huang Haiying , Kardomateas George A. 
Published: December 2021

Abstract
The objective of the current paper is to model the crack branching off an interface between two anisotropic materials represented as thin strips subject to mixed Mode I/Mode II static loads. The dislocation technique is used to formulate the problem. The solution for a dislocation in an infinite domain composed of two half-plane anisotropic materials is applied, and the elastic solution for a dislocation in a bi-material anisotropic thin strip is achieved by applying two arrays of dislocations on the thin strip boundaries.
Vibration Control Using Piezoelectric Material With High Order Nonlinearity
Authors: Tang J. , Wang K. W. 
Published: December 2021

Abstract
Larger control authority can be achieved by applying higher electrical field to piezoelectric actuators. This, however, will cause significant nonlinearities, such as high order relation between actuation strain and applied field and material hysteresis, in the piezoelectric material. The present paper is on the development of a nonlinear structural control law using piezoelectric material with high order nonlinearity. Analytical and experimental efforts are carried out to quantify the piezoelectric nonlinearities at high field levels. A nonlinear control scheme, which is featured by a resistor/inductor shunting actuator network and a sliding mode control algorithm, is proposed for the vibration control of a generic beam structure. Because of the robust nature of the sliding mode approach, this control scheme is also capable of compensating for other nonlinearities, such as the material hysteresis.
Distributed Sensing and Shape Control of Piezoelectric Bimorph Mirrors
Authors: Redmond James M. , Barney Patrick S. , Henson Tammy D. , Main John A. , Martin Jeffrey W. 
Published: December 2021

Abstract
As part of a collaborative effort between Sandia National Laboratories and the University of Kentucky to develop a deployable mirror for remote sensing applications, research in shape sensing and control algorithms that leverage the distributed nature of electron gun excitation for piezoelectric bimorph mirrors is summarized. A coarse shape sensing technique is developed that uses reflected light rays from the sample surface to provide discrete slope measurements. Estimates of surface profiles are obtained with a cubic spline curve fitting algorithm. Experiments on a PZT bimorph illustrate appropriate deformation trends as a function of excitation voltage. A parallel effort to effect desired shape changes through electron gun excitation is also summarized. A one dimensional model-based algorithm is developed to correct profile errors in bimorph beams. A more useful two dimensional algorithm is also developed that relies on measured voltage-curvature sensitivities to provide corrective excitation profiles for the top and bottom surfaces of bimorph plates. The two algorithms are illustrated using finite element models of PZT bimorph structures subjected to arbitrary disturbances. Corrective excitation profiles that yield desired parabolic forms are computed, and are shown to provide the necessary corrective action.
A Study of Constrained Layer Damping Models Under Clamped Boundary Conditions
Authors: Huang Peter Y. H. , Reinhall Per G. , Shen I. Y. 
Published: December 2021

Abstract
The most commonly used beam model for constrained layer damping was developed by Mead and Markus in 1969. Although three displacement variables were used in the model, only two of them were independent. As a result, boundary conditions that are allowed in the Mead-Markus formulation may sometimes be limited. For example, a simple lab setup often consists of a cantilevered base beam with free-free constraining layer. In this case, the axial displacements of the beam and the constrained layer are independent at the cantilevered end. This boundary condition violates the basic assumption of the Mead-Markus model and cannot be described under the Mead-Markus formulation. In this paper, we investigate a modified model that is able to incorporate such boundary conditions by using three independent displacement variables. The modified model is demonstrated on a cantilevered beam with a free-free constrained layer treatment. The frequency response functions were obtained both experimentally and analytically. Our results show that the modified model is able to accurately predict vibration response. An investigation into the frequency response functions of the Mead-Markus model under similar boundary conditions is also reported.
Interactions of Microcarriers in Simulated Microgravity
Authors: Meaney David F. , Johnston Eric D. , Litt Mitchell , Pollack Solomon R. 
Published: December 2021

Abstract
In this study, we developed a numerical model that simulated the simultaneous motion of several microcarriers in the simulated microgravity environment of the NASA HARV bioreactor. Simulations were used to predict the interaction and collision of these multiple particles under different initial seeding densities. In addition, the quasi-steady particle distribution for beads which are lighter than the surrounding fluid is presented. Results show that the frequency of particle collision increases significantly only when the initial seeding density is close to the maximum density. In addition, a stable particle density, with a relatively constant number of particle interactions, is achieved with all seeding densities using beads that are lighter than the surrounding fluid. These results are similar to those measured experimentally for light beads — beads co-locate within a sub-region of the HARV bioreactor, and achieve a consistent final bead density that is independent of the starting seeding density.
Observation of Vascular Injury After Freezing: Investigating the Response of Normal Skin and Subcutaneous AT-1 Tumor Tissue to Cryosurgery in the Dorsal Skin Flap Chamber
Authors: Hoffmann Nathan E. , Swanlund David J. , Bischof John C. 
Published: December 2021

Abstract
Two main mechanisms have been explored in an attempt to explain injury to the cells of tissues due to freezing in vivo. The first is direct cellular injury caused by injurious osmotic changes and ice crystal formation that happens as a result of freezing (Mazur, 1984). The second is host response injury caused by the vascular damage and immunologic response in response to freezing (Gage and Baust, 1998). The amount of injury caused by freezing appears to vary with tissue type and thermal history of the freezing protocol. The hypothesis of this study was that host response injury, specifically vascular injury, causes the majority of tissue necrosis at the edge of a frozen region and therefore determines the size of the lesion seen after in vivo freezing. Many investigations have previously made a qualitative correlation between thermal history, vascular injury, and tissue necrosis (e.g. Greene. 1943 and Rabb et al., 1974). We chose the dorsal skin flap chamber (DSFC) implanted in the Copenhagen rat as the cryosurgical model for this study. This in vivo freezing model appears insensitive to the immunologic phenomenon (Hoffmann et al., 1999) and allows us to monitor thermal history and investigate both vascular and tissue injury in response to cryosurgery.
A Model of Tissue Charring During Interstitial Laser Photocoagulation: Estimation of the Char Temperature
Authors: Whelan William M. , Wyman Douglas R. 
Published: December 2021

Abstract
Interstitial laser photocoagulation (ELP) was performed ex vivo in lean bovine muscle by delivering 1.5 W of continuous-wave 1064 nm Nd:YAG laser energy from a 400 μm core plane-cut optical fiber. The strategy for determining the char temperature involved measuring temperatures where thermal gradients were reduced, and extracting times at which temperature-time profiles displayed interesting nonlinear changes. These times were used to guide a finite difference thermal model, calculating transient temperatures based on two physical descriptions of tissue charring. Modifications in the optical and thermophysical properties due to tissue coagulation (T ≥ 60 °C) and vaporization of tissue water (T ≥ 100°C), respectively, were considered. By placing measured charring dimensions, 2.0 ± 0.3 mm, on calculated temperature-distance profiles, a tissue charring temperature of 414 ± 92°C was estimated.
Non-Invasive Measurement of Counter-Current Flows in a Hemodialyzer Using Fourier-Velocity Magnetic Resonance Imaging
Authors: Hardy Peter A. , Poh Churn K. , Huang Zhongping , Liao Zhijie , Gao Dayong 
Published: December 2021

Abstract
The objectives of this paper are: (1) to show the usefulness of Fourier-velocity magnetic resonance imaging (MRI) technique in validating numerical models in the design of an optimal hemodialyzer, and (2) in characterizing non-invasively the spatial counter-current flow distribution in a hemodialyzer. The relative amount of flows at different velocity range for both the blood and dialysate compartments of a CT190G hemodialyzer (Baxter Healthcare Corporation, Deerfield, IL) was measured non-invasively using the Fourier-velocity MRI technique. This technique was first validated by imaging a flow phantom. The flow phantom consisted of two parallel-Plexiglas tubes with flows introduced counter-currently in each tube. In both cases, twenty-four images were acquired at thin cross sections corresponding to the flows at the mean velocities {−24, ..., −4, −2, 0,+2, +4, ..., +22} mm/s. These images were acquired at the mid-section of both the two-parallel-Plexiglas tube and the hemodialyzer. The empirical results were found to be comparable to numerical results computed from the Navier-Stokes equations. Images of the hemodialyzer demonstrated a wide spatial flow distribution both inside the blood and dialysate compartments. A segment of the hemodialyzer had reduced intra-fiber flow indicating a region of occlusion in the blood compartment. Flow at the dialysate compartment was greater at the periphery of the hollow-fiber bundle adjacent to the housing.
Modeling of Crack Growth in Thin Sheet Aluminum
Authors: Siegmund T. , Brocks W. , Heerens J. , Tempus G. , Zink W. 
Published: December 2021

Abstract
The present study reports on the application of a cohesive zone model to the analyses of crack growth in thin sheet specimen of a high strength aluminum alloy. In addition to the elastic-plastic material properties, the two parameters cohesive strength and cohesive energy describe material separation. For the sheet specimen under investigation the cohesive energy is determined via a numerical-experimental approach using tests on notched tensile specimens as well as a damage indicator. The cohesive energy is found to be close to the corresponding value of plane strain fracture toughness. The cohesive strength is approximately twice the yield strength. With these two additional material parameters being determined crack growth experiments in center crack panels are analyzed. Good agreement with experimental records is found. Finally the applicability of the model to study complex crack configurations as in multi-site damaged specimens is demonstrated.
Three-Dimensional Analyses of Single Rivet-Row Lap Joints — Part II: Elastic-Plastic Response
Authors: Iyer K. , Rubin C. A. , Hahn G. T. 
Published: December 2021

Abstract
Three-dimensional finite element analyses of an elastic-plastic, single rivet-row, aluminum lap joint are presented and compared with previous results for linear elastic models. The calculations treat non-countersunk aluminum and steel rivets, 3 different configurations of countersunk rivets as well as two values of the friction coefficient. The compliance of the connection, rivet tilt, the stresses in the panels, peak plastic strains and the contact pressures and slip amplitudes at the rivet-panel and panel-panel interfaces are evaluated. The transverse, axial, and shear stress distributions and the stress concentrations generated in four different rivets are derived from the linear elastic models and related to the rivet geometry. Laboratory measurements of the lap joint compliance and local out-of-plane displacements that support the reliability of the finite element analyses are presented.
Bolt Thread and Head Fillet Stress Concentration Factors
Authors: Lehnhoff Terry F. , Bunyard Bradley A. 
Published: December 2021

Abstract
Linear finite element analysis (fea) was performed to determine stress concentration factors for the threads and the bolt head fillet in a bolted connection. The fea models consisted of axisymmetric representations of a bolt and two circular steel plates each 20 mm in thickness. The bolts studied were 8, 12, 16, 20, and 24 mm diameter grade 10.9 metric bolts with the standard M thread profile. The threads were modeled at both the minimum and maximum allowable depths. The fillet between the bolt shank and bolt head connection was modeled at its minimum radius. Each bolt was loaded to its proof strength. A comparison is made to stress concentration factors typically used in bolted connection design. Stress concentration factors in the head fillet were 3.18, 3.23, 3.63, 3.58, and 3.90 for the 8, 12, 16, 20, and 24 mm bolts, respectively. Thread stress concentration factors were highest in the first engaged thread and decreased in each successive thread moving toward the end of the bolt. Stress concentration factors for the shallow thread models ranged from 1.17 to 4.33, 0.87 to 4.32, 0.83 to 4.67, 0.87 to 4.77, and 0.82 to 4.82 for the 8, 12, 16, 20, and 24 mm bolts, respectively. Likewise, stress concentration factors for the deep thread models ranged from 1.18 to 4.80, 0.88 to 4.80, 0.78 to 5.12, 0.83 to 5.17, and 0.82 to 5.22 for the 8, 12, 16, 20, and 24 mm bolts, respectively.
Comparison of Two Axisymmetric Finite Element Models of Threaded Connections
Authors: Hommel Mark 
Published: December 2021

Abstract
Predicting the fatigue life of threaded connections using finite element analysis generally requires a 2-D axisymmetric model capable of handling non-axisymmetric loading in order to simulate an applied bending moment. This is desirable from the standpoint of computer run time, as compared with the alternative approach, namely, developing a full 3-D model. Unfortunately, due to their esoteric nature, the 2-D axisymmetric elements with non-axisymmetric loading capability are not supported by the software vendors as well as the other elements, hence pre- and post-processing are more challenging. In addition, due to the Fourier representation of the non-axisymmetric load, computer run time and storage is increased significantly over that of a strictly 2-D axisymmetric model. In view of this, common practice has been to use instead the conventional axisymmetric model with an equivalent applied axial tensile stress equal to the mean bending stress through the wall thickness in order to simulate the bending moment and thereby avoid the necessity for non-axisymmetric loading. The question therefore arises as to how well the results from the strictly axisymmetric model agree with the results from the axisymmetric model with non-axisymmetric loading capability.
The purpose of this paper is to compare the results of the two models. A 5-1/2 F.H. threaded connection is modeled by means of a commercial finite element code. First, the axisymmetric model with non-axisymmetric loading capability is treated and results are obtained. Second, the axisymmetric model with applied equivalent tensile load is examined and its results are compared with the former model. It is found that the value of the primary variable of interest for quantification of fatigue life, namely, alternating stress, agrees between the two models within 4%. Thus, it is concluded that the simplified model provides a viable alternative for modeling fatigue life of threaded connections.
Analysis of Interfacial Fracture in Thin Films Subjected to Thermal Loading
Authors: Gosz M. , Okyar A. F. 
Published: December 2021

Abstract
We consider the problem of a three-dimensional interface crack between a film and a substrate to gain a better understanding of how the problem of peeling in film-substrate material systems subjected to thermal loading can be alleviated. We assume that the crack lies in the plane of the interface and is located at one of the free comers of the structure. The fracture parameters (mixed mode stress intensity factors, phase angles and the energy release rate) along the crack front are obtained using an interaction energy integral technique developed by Gosz et al. (1998) for analysis of three dimensional, bimaterial interface cracks. The technique is a very accurate domain integral method that is employed as a post-processing step after a finite element solution for the stress, strain, and displacement fields in the solid has been obtained. In the paper, we investigate the effect of film thickness on the fracture parameters and the results are discussed.
Detailed Stress Analysis of a Spherical Acrylic Submersible by 3-D Finite Element Modeling
Authors: Das Partha S. 
Published: December 2021

Abstract
Harbor Branch Oceanographic Institution (HBOI) designed, built and has operated two JOHNSON-SEA-LINK (JSL) manned submersibles for the past 25 years. The JSL submersibles each incorporate a 66–68 in. (1.6764–1.7272 m) OD, 4–5.25 in. (0.1016–0.13335 m) thick acrylic two-man sphere as a Pressure Vessel for Human Occupancy (PVHO). This type of spherical acrylic sphere or submersible was first introduced in around 1970 and is known as Naval Experimental Manned Observatory (NEMO) submersibles. As the demand increases for ocean exploration to 3000 ft. (914.4 m) depth to collect samples, to study the ocean surfaces, the problem of developing cracks at the interface of these manned acrylic submersibles following few hundred dives have become a common phenomena. This has drawn considerable attentions for reinvestigation of the spherical acrylic submersible in order to overcome this crack generation problem at the interface. Therefore, a new full-scale 3-D nonlinear FEA (Finite Element Analysis) model, similar to the spherical acrylic submersible that HBOI uses for ocean exploration, has been developed for the first time in order to simulate the structural behavior at the interface and throughout the sphere, for better understanding of the mechanical behavior. Variation of the stiffness between dissimilar materials at the interface, lower nylon gasket thickness, over designed aluminum hatch are seemed to be few of the causes for higher stresses within acrylic sphere at the nylon gasket/acrylic interface.
Following the basic understanding of the stresses and relative displacements at the interface and within different parts of the submersible, various models have been developed on the basis of different shapes and thickness of nylon gaskets, openings of the acrylic sphere, hatch geometry and its materials, specifically to study their effect on the overall performance of the acrylic submersible. Finally, the new model for acrylic submersible has been developed by redesigning the top aluminum hatch and hatch ring, the sphere openings at both top and bottom, as well as the nylon gasket inserts. Altogether this new design indicates a significant improvement over the existing spherical acrylic submersible by reducing the stresses at the top gasket/acrylic interface considerably. Redesigning of the bottom penetrator plate, at present, is underway. In this paper, results from numerical modeling only are reported in details. Correlation between experimental-numerical modeling results for the new model will be reported in the near future.