bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Pavement Roughness on Tire Noise
Authors: Ruhala Richard J. , Burroughs Courtney B.
Published: December 2021

In this study, the influence of the levels of pavement roughness on tire noise is examined using Nearfield Acoustical Holography (NAH) to measure noise from single tires mounted on a two-wheel trailer towed over different types of pavements. Contributions to the radiated noise from the leading edge, trailing edge, and sidewall of two tires are identified. Two experimental tires — a blank tire and a monopitch tire — are evaluated on three pavements — smooth asphalt, stud-damaged concrete, and Ellsworth — at 56 km/hr. From the measured complex pressure, acoustic intensity is reconstructed on side plane of the tires using NAH procedures. Additionally, sound power spectra levels are presented. Tire noise generating mechanisms associated with each pavement are inferred from measurements. The experimental results are compared with theories on pavement-induced tire noise available in the literature.
A Hybrid Track Model for Studying Dynamic Track/Sprocket Contact
Authors: Ma Zheng-Dong , Perkins Noel C.
Published: December 2021

Tracked vehicles are propelled by the engagement of track pitches and a drive sprocket. This sprocket, referred to as a tumbler for the large tracked mining vehicles considered herein, may wear quickly under the action of the considerable contact forces that develop with the track. This paper summarizes a model of the track/tumbler seating process and the contact forces that control abrasive wear. A vehicle model is developed that employs a hybrid model for the track. This hybrid model combines a multibody model of the track within the seating region of the tumbler with a continuous model of the track elsewhere in the track circuit. The hybrid model is then employed to simulate the track/tumbler interactions and the associated nonlinear contact phenomena. This new modeling approach promotes accuracy within the track/tumbler contact region with few degrees of freedom outside this region where spatial resolution is less important.
Evaluation of Ballistic Impact Damage of Fiber Reinforced Plastic Laminates Bonded by Polycarbonate Facesheets
Authors: Hosur M. V. , Vaidya U. K. , Haque A. , Kulkarni M. , Kulkarni R. , Jeelani S.
Published: December 2021

Fiber reinforced polymer matrix composites are being increasingly used in many applications including aerospace, armored vehicle, marine and sporting industries. They provide the advantage of high specific stiffness and specific strength as compared to conventional metallic materials. However, they are well known by their vulnerability to threats like impact loading that occurs normally in the transverse direction. Hence, there is a need to improve the damage resistance in the transverse direction at minimum weight penalty. In this current investigations, a two component material system made of fiber reinforced laminates bonded by a polycarbonate facesheet was studied. Laminates made of both unidirectional graphite/epoxy prepregs and S2-glass twill weave woven fabric/SC-15 resin systems were used in the study. Specimens of size 304.8 × 304.8 mm were made using different thickness ratios of facesheet and the backing laminate. Three different thicknesses of s2-glass laminates (3.17, 4.31 and 5.71 mm) were used to bond to two polycarbonate sheets of thickness 2.54 and 3.17 mm each. Similarly, three different thickness of graphite/epoxy laminates (2.05, 3.75 and 7.62 mm) were used to bond to polycarbonate facesheet of thickness 1.00, 3.175, and 4.30 mm. The ballistic tests are performed with a space test setup using fragment simulating projectiles(FSP). The ensuing damage was evaluated using ultrasonic C-scan technique using pule-echo immersion method.
Improvement of Vibration Damping Capacity and Fracture Toughness in Composite Laminates by the Use of Polymeric Interleaves
Authors: Gibson Ronald F. , Zhao Hui
Published: December 2021

It is shown that simultaneous improvement of vibration damping capacity and interlaminar fracture toughness in composite laminates can be achieved by using polymeric interleaves between the composite laminae. The specific case of Mode II interlaminar fracture toughness and flexural damping capacity of interleaved composite laminates is studied. Graphite/epoxy, E-glass/epoxy and E-glass/polyetherimide composite laminates with polymeric interleaves of several different thicknesses and materials were tested using both the end notch flexure (ENF) test for Mode II fracture toughness and the impulse-frequency response test for flexural damping capacity. The Mode II energy release rate GIIc for all three composites increased linearly with increasing interleaf thickness up to a critical thickness, then dropped off with further increases in thickness. The damping loss factor η for all three composites increased linearly with increasing interleaf thickness up to the maximum thickness. Analytical models for predicting the influence of interleaves on GIIc and η are developed, along with a hypothesis for the critical thickness effect with regard to fracture toughness.
Nondestructive Identification of Steel Bars by Modal Damping Measurements
Authors: Ayorinde Emmanuel O. , Morle Beverley , Zheng Zhiyang
Published: December 2021

This paper addresses the determination of modal vibration parameters for two batches of differently-treated steel reinforcement bars, as a means towards developing a method for easy identification of the state of mechanical goodness of such bars. The parameters measured for each bar are the resonance frequencies and corresponding modal damping loss factors for the first three vibration modes. This was done with the bar mounted in the cantilever mode, with varying free lengths. Inferences were made from the results to show which parameters would be suitable as state identifiers for bar specimens.
Finite Element Modeling and Advanced Imaging by Instrumented Tap Testing
Authors: Dayal V. , Choudhary Tanveer A. , Hsu D. K. , Peters J. J. , Barnard D. J.
Published: December 2021

Tap test is a very trusted and well used technique for the non-destructive evaluation of composite materials. Conventionally, a coin has been used for the tapping and the inspector listens to the resulting sound. The more advanced force response provides a number which can be correlated to the damage.

A finite element model of the test has been developed with full honeycomb features and a dynamic tap is applied. The goal is to measure the reduction in stiffness of the structure due to simulated defects. This could be useful to both the manufacturer, as well as the user, to know the change in the structural response of the structure for a possible pass/fail criteria.

We will also present results of an instrumented tap test with scanner. The main emphasis is on the testing of honeycomb core with composite face sheet panels. The results presented show the sensitivity of the tap test on simulated defects in honeycomb panels.
A Comparison of Matched-Field and Pseudo-Inverse Methods for Source Identification on a Frame Structure
Authors: Craun Matthew A. , Feit David
Published: December 2021

The combined use of pseudo-inverse and matched-field processing methods is investigated for localizing and characterizing a broad-band random vibration source on a lightly-damped finite frame structure. The low-frequency range where global modes of the frame are dominant in the response is considered. Experimental results for two different sensor array geometries are compared. Also, the use of numerically-derived transfer functions is demonstrated for each of the processing methods. The results indicate that a combined use of matched-field and pseudo-inverse methods allows for a more complete characterization of the frame excitation than either method used exclusively.
Visualization of Acoustic Pressure Radiation From Complex Vibrating Structures
Authors: Rayess Nassif , Wu Sean F.
Published: December 2021

This paper demonstrates visualization of the radiated acoustic pressures from a complex structure by using the Helmholtz Equation Least Squares (HELS) method (Wang and Wu, 1997; Wu and Wang, 1998; Wu and Yu, 1998). The structure under consideration has the same geometry and dimensions as those of a real, full-size passenger vehicle front end. Random noises generated by a high-fidelity loudspeaker installed inside the vehicle buck are measured at certain distances away from the vehicle surface. These measured signals are taken as the input to a computer model based on the HELS method. Experiments are conducted inside a 12’ by 12’ by 6.5’ walk-in size, fully anechoic chamber at the Acoustics, Vibration and Noise Control Laboratory of Wayne State University. The reconstructed acoustic pressures on the vehicle buck surface and in the field are compared with the measured data at the same locations. Also shown are comparisons of the reconstructed and measured acoustic pressure spectra at various locations on the vehicle buck surface. Results show that good agreements can be obtained with relatively few expansion functions in the low-to-mid frequency range. The accuracy of reconstruction, however, decreases with the increase of the excitation frequency and measurement distance as expected. Nevertheless, the HELS method is shown to be relatively insensitive to the complexities of a vibrating structure, which may make it potentially a viable noise diagnostic tool for engineers.
Radiation Efficiency of Convected Fluid Loaded Plates
Authors: Frampton Kenneth D.
Published: December 2021

The radiation of sound from geometrically simple vibrating structures into stationary fluids is well understood. However, to date, very few investigations have considered the effects that a convected fluid has on structural acoustic radiation. The purpose of this investigation is to quantify the effects of changes in flow velocity on the sound radiated from a vibrating elastic plate into a convected fluid medium. The discussion will include a description of modeling an elastic plate imbedded in an infinite baffle and radiating into a semi-infinite convected fluid field. Furthermore, the importance of a coupled model approach (where the fluid pressures generated by the plate motion in turn force the plate response) will be discussed. It will be demonstrated that the effects of convected fluid loading on sound radiation can be very significant.
Modeling and Analysis of a Tunable Bistable MEMS for Opto-Mechanical Computational Logic Elements
Authors: Saif M. Taher A. , Miller Norm R.
Published: December 2021

We present the design, analysis, and testing of a tunable bi-stable MEMS device that changes state when subjected to a threshold force in the range of pN to μN. It consumes power during change of state, but not while maintaining a state. Depending on the design and tuning, the state change can be initiated by even a moderate power laser beam that generates force by the impacts of its photons. The device presents itself as a potential bistable multivibrator (flip-flop), as well as the basic component of combinational logic elements, such as AND and OR gates, thus opening the door for low power digital opto-mechanical computing in normal to harsh environments. Several designs of the combinational logic elements are provided for optomechanical computing. In addition to bi-stability, the device shows a rich and complex set of dynamical behavior (e.g., chaotic response) when subjected to certain parametric excitations.
X-Ray Fabrication of Repetitive Structures
Authors: Liu Yadong , Sheng Paul
Published: December 2021

The fabrication of repetitive mechanical structures in millimeter range by deep x-ray micromachining is reported in this paper. With higher energy and wider x-ray beam lines available, macro-sized mechanical structures with micro-level features can be fabricated by the modified LIGA process to meet the need on high aspect ratio, high precision components in advanced applications. Through metrology study, better understanding of the process characteristics is achieved to provide important information on error modes in pattern transfer, which could be ultimately used in product design and process planning. Case studies of a rectangular HESSI grid structure and involute gear teeth are presented.
Viscous Damping of On-Substrate Torsional Micromirrors
Authors: Kim Eung-Sam , Han Ki-Ho , Cho Young-Ho
Published: December 2021

In this paper, we present theoretical and experimental study on the viscous damping of the on-substrate torsional micromirrors, oscillating near the silicon substrates. In the theoretical study, we develop theoretical models and test structures for the viscous damping of the on-substrate torsional micromirrors. From a finite element analysis, we obtain the fundamental modes of the torsional micromirrors, fabricated by the surface-micromachining process. From the electrostatic test of the fabricated devices, rotational velocity of the micromirrors has been measured at the atmospheric pressure using the Mach-Zehnder interferometer system. Experimental damping coefficients have been extracted from the least square fit of the measured rotational velocity within the filter bandwidth of 150kHz. We have compared the theoretical values and the experimental results on the dynamic performance of the micromirrors. The theoretical analysis overestimates the resonant frequency in the amount of 15%, while underestimating the viscous damping in the factors of 10%, respectively.
High Performance Electrostatic Air Valves Formed by Thin-Film Lamination
Authors: Biegelsen David K. , Cheung Patrick , Swartz Lars E. , Jackson Warren B. , Berlin Andrew A. , Lau Rachel
Published: December 2021

Electrostatic flap valves for rapidly modulating air flows through directed jets have been fabricated by simple lamination techniques as extensions to standard printed circuit board technology. The flaps have thicknesses of a few microns whereas the lateral dimensions are several millimeters. The laser cutting and lamination processes are described here and the characteristics of the valves are presented. Flow rise and fall times of order 1 ms are demonstrated, the variations of response times with drive voltage and pressure differential are shown, and lifetimes greater than 4 × 108 are reported.
A Silicon Micromachined Valve Driven by a Bi-Stable Electromagnetic Actuator
Authors: Böhm S. , Burger G. J. , Korthorst M. T. , Roseboom F.
Published: December 2021

In this contribution a micromachined open/closed valve is presented which is driven by a conventionally manufactured bistable electromagnetic actuator. Basically the micromachined valve part, 7 × 7 × 1 mm3 in dimension, is a sandwich construction of two KOH etched wafers with a specially formulated silicone rubber layer in between. This rubber sheet forms a flexible flow path, which can be open and closed to control a fluid flow. In order to provide a large stroke of about 200 μm, a precision-engineered bi-stable electromagnetic actuator was selected. This actuator consists of a spring-biased armature that can move up and down in a magnetically soft iron housing, incorporating a permanent magnet and a coil. It will be shown that this combination of micromachined and precision-engineered components provides the required low dead volume on the one hand and a large actuator stroke on the other. Another benefit of the application of a bi-stable actuator is the fact that only energy is needed in order to switch between the open and closed state. Moreover, the large stroke makes the valve particle tolerant thus allowing media like cell suspensions and whole blood.
A Stiction Study via C-V Plot Electrostatic Actuation/Latching
Authors: O’Brien Gary , Lin Liwei , Monk David J.
Published: December 2021

We have demonstrated a stiction study methodology on the microscale via an electrostatically actuated polysilicon parallel plate capacitor. The actuator was used to cause physical contact between two polysilicon microstructures. C-V (capacitance-voltage) plots were used to extract mechanical parameters, including surface energy (J/m2), force of adhesion (N), and spring constant (N/m). An average surface energy of 8.9 mJ/m2 with corresponding standard deviation (σ) of 0.8 mJ/m2 was observed regarding polysilicon adhesion. The average force of adhesion was calculated to be 13.3 μN (σ = 1.2 μN) for a contact surface area of 1.256 × 10−9 m2. The calculated Z-axis spring constant was 15.9 N/m (σ = 1.6 N/m) as compared to the theoretical value of 16.8 N/m.
Implementation and Analysis of Polymeric Replication by Micro-Injection Molding
Authors: Shah Jatan , Su Yu-Chuan , Lin Liwei
Published: December 2021

Injection molding technique for the replication of polymeric microstructures is demonstrated. By means of appropriate process control, traditional injection molding technique can be applied for the replication of polymeric microstructures. Using wet-etched silicon wafers as mold inserts, we have successfully predicted, improved, and optimized the replication results. The behavior of polymer melt in micro mold cavity is characterized by both experimental and simulation results. Temperature parameters are identified as the key factors that decisively determine the quality of molded microstructures. Optimization of the molding process is performed using simulation and experiment evaluation approach. This technique has potential applications for MEMS fabrication at relatively lower cost with a short cycle time. We believe this adoption of the injection molding process to micro-fabrication will lead to a promising technique for MEMS devices.
Low Voltage Dual-Mass Oscillator
Authors: Dyck Christopher W. , Allen James J. , Huber Robert J.
Published: December 2021

In this work we explored an alternative approach to mechanical oscillator design: the dual-mass oscillator. A two-degree-of-freedom system forced at antiresonance can attain larger vibration amplitudes at a given drive voltge with parallel-plate actuation than with comb drive actuation. Amplitudes of 0.85 μm in air at atmospheric pressure were observed with supply voltage under 5V. Amplitudes at resonance and antiresonance were measured. The parallel plate structure exhibited instability at low drive voltages because of the nonlinear drive. Structures with stiffer springs will solve this problem. An expression for the electrostatic force vs. displacement was developed using finite element methods. When this expression was used in simulations, the absorber mass steady-state amplitude closely matched measurements. Finite element analysis was done on the dual-mass oscillator. The natural frequencies of the out-of-plane modes were close to the in-plane modes and could potentially cause problems, depending on the magnitude of the out-of-plane force.
Experimental and Numerical Study on Micro-Stereolithography of Ceramics
Authors: Sun C. , Jiang X. N. , Zhang X.
Published: December 2021

Micro-stereolithography (μSL) uses laser light to solidify UV-curable resin mixed with concentrated ceramic powders. During the μSL process, the light scattering from the particle suspension is found to significantly influence the fabrication resolution and curing depth which are critical for the complex 3D microfabrication. In this work, we developed a novel doping technique to substantially reduce the light scattering; thus, enhance the fabrication precision and control. Both Monte-Carlo simulations and experimental studies are carried out to understand the detailed micro-scale optical scattering, chemical reaction (polymerization) and their influences to fabricated line-width.
Characterization of Silicon/Glass Anodic Bond Initiation Toughness
Authors: Labossiere Paul E. W. , Dunn Martin L. , Cunningham Shawn J.
Published: December 2021

We describe an approach to characterize the initiation toughness of silicon/glass anodic bonds based on the universal stress state that exists at the most common site of fracture initiation: the silicon/glass interface corner. The approach consists of a rigorous mechanics-based framework to assess the initiation toughness of anodic bonds; it can be used to rank bond toughness as a function of processing parameters and to facilitate the design of reliable bonds. By initiation toughness, we mean the resistance of anodic bonded interfaces to crack initiation under mechanical and/or thermal loading. The framework is universal in that it is independent of the bond size (area), and it is possible to discriminate between different failure modes via the initiation toughness. In order to validate the approach we designed and fabricated relatively simple anodic bond test specimens and carried out a mechanical test program to characterize bond toughness. We find that while failure stresses vary significantly with bond area, the inferred toughness is invariant with respect to bond area.
Multiple Through-Wafer Interconnects for Stacking of Microsystems
Authors: Heschel Matthias , Rasmussen Kurt , Kuhmann Jochen F. , Bouwstra Siebe
Published: December 2021

This paper describes a novel technology for multiple wafer frontside to backside interconnects, which has been applied to a multifunctional interconnect layer for an integrated microphone for hearing aid applications. Besides the interconnect layer with relatively large through-holes the stack consists of the microphone itself and an integrated circuit chip for signal conditioning. The patterning of the metallization on the interconnect wafer has been done using electrodepositable photoresist as mold for electroplating of a variety of metals. For the interconnect metallization we use copper. The bonding pads on the microphone side of the interconnect layer have been provided with under bump metallizations (UBM) and solder bumps. The IC side features a top surface metallization (TSM) suitable for conductive adhesive bonding. The realized feedthrough wires show good electrical performance in terms of low series resistance (100 mΩ) and small parasitic capacitance (< 1 pF).
Design and Development of a Unit-Use Cartridge for Coagulation Testing in Whole Blood
Authors: Cheadle Rhonda , Maczuszenko Andy , Opalsky Cindra Widrig
Published: December 2021

The following describes the development of a disposable cartridge for use at the patient bedside to perform traditional coagulation assays on fresh whole blood samples. The cartridge provides a means by which a blood sample can be metered and quantitatively mixed with reagents that activate the coagulation cascade. Clot formation is subsequently detected using a microfabricated sensor housed within the cartridge. The functional features of the cartridge and sensor are described.
Analysis of Absorbed Power Distribution in Ride Dynamics — Evaluation of Driver’s Comfort
Authors: Tong Rick T. , Amirouche Farid , Nishiyama Shuji
Published: December 2021

This paper presents an analytical model for the evaluation of the distribution of the absorbed power and how the body reacts to the road excitation. “Absorbed power” is a popular method used to evaluate ride comfort. Since Pradko and Lee introduced it in 1960’s [1,2], researchers focused on the “absorbed power” transmitted to the body as a single indicator of body tolerance and fatigue. How the body absorbs energy and how it distributes it remains a mystery. This paper attempts to shed some light on how this energy is transmitted to different parts of the body and what is at stake when the input conditions change. A six degree of freedom (dof) lumped mass model was developed to investigate the energy absorption and the work performed by the muscles (springs and dampers) during a rough ride. A better understanding of the energy flow between the body segments may give us an idea on how the seat and its suspension should be designed.
The Biplanar Bicycle
Authors: Reinholtz C. F. , Bay J. , Soper R. Randall , Abbott M. , Grove D.
Published: December 2021

Two wheeled vehicles, or bicycles, are widely accepted devices. Almost invariably, however, the term bicycle brings to mind a planar, statically unstable, two-wheel vehicle that must be kept upright by the dynamic control of the rider. This mindset may be logical in the limited context of some human-controlled devices, but it may limit our creative potential when considering the design of autonomous vehicles and novel means of transport. Here we attempt to challenge mindset and myth, asking the reader to consider a concept that may be counterintuitive, but that is rooted in the sound application of engineering principles. We propose the biplanar bicycle.
Future Programming for the Bioengineering Division of ASME
Authors: Miller Gerald
Published: December 2021

The Bioengineering Division of ASME has recently undergone considerable discussion regarding the future of programming at the winter meeting (the International Congress — formerly the WAM) and at the Summer Bioengineering meeting. There has been considerable debate as to what is in the best interest of the Bioengineering Division and its members — should the programming stay the same? Should all programming occur only at the summer meeting? Only at the winter meeting? Should the Summer meeting occur annually, rather than every odd year? Should the Bioengineering division program at the winter “slot” jointly with BMES and/or EMBS?

Much of these discussions have occurred because some BED members feel that the trend of the division is towards life science oriented papers and that the ASME congress is not well suited for such presentations. Others bemoan the proliferation of scientific meetings which begs the issue of which meeting(s) should be eliminated for the sake of others.

A brief presentation of the mechanisms of programming at the ASME congress will take place as well as the history of BED programming at both the winter and summer meetings. Discussions of the pros and cons of continued programming at the winter meeting (the Congress) will follow along with alternatives such as joint programming with other societies.

The format of the session will be as follows:

• Twenty minute presentation on the current status of programming at the winter and summer meetings

• Ten minute question and answer session on current programming

• Forty five minute open forum on future programming mechanisms for BED

Within this open forum, we hope to hear from all BED members on a number of issues regarding programming. These include the following options:

• Continue with the current formats: annual programming at the winter meeting (congress) and biannual programming at the summer meeting.

• Programming annually at both the winter and summer meetings

• Program biannually at the winter meeting (congress) and program annually at the summer meeting – causes some problems which must be explained

• Program annually at the summer meeting and discontinue programming at the winter meeting in lieu of joint programming with another society.

• Another programming plan

This session will allow a lengthy discussion of BED members regarding the future of programming at ASME and the potential effects on publications in the Journal, in the conference proceedings and on the finances of the Division (as the summer meeting is a major source of income for the division).
Computational Analysis of Indicator Functions for Intimal Thickening in Branching Blood Vessels
Authors: Buchanan J. R. , Longest P. W. , Hyun S. , Kleinstreuer C.
Published: December 2021

Intimal thickening and thrombi formation in medium to large blood vessels due to atherosclerotic lesions and/or intimal hyperplasia are the leading causes of death in the western world. Balloon angioplasty with stenting, bypass surgery and patch reconstruction are some of the mechanical techniques currently applied to reopen or bypass occluded blood vessels. Thus, it is of interest to develop suitable indicator functions which encapsulate aggravating flow patterns, in order to determine susceptible sites of intimal thickening and/or thrombi formation. These indicator functions are then applied in four case studies to interprete experimental/clinical data of intimal thickening and design blood vessel geometries which potentially improve long-term patency rates.
First Passage Measurements of Dispersion Coefficients for Suspension Flows
Authors: Eckstein Eugene C. , Leggas Mark
Published: December 2021

We report results of an experimental protocol for determining effective diffusion coefficients in suspension flows in thin channels. The method is based on the first-passage method (FPM), a well-known aspect of probability theory. Images of identifiable individual particles are collected at a regular rate by a video camera. The times needed for individual particles to move selected distances on either side of the original position are measured. Such events are individually the “first passage” for the selected net distances. Repeated evaluation of this statistic for the same initial conditions is done so that the history of axial motion can be summarized in a statistical manner. All images are collected in a moving frame of reference in order to limit more precisely the initial time and to make observations in a specified region of the flow. The protocol has been used in rectangular channels approximately 50 micrometers high and 500 micrometers wide to collect observations that were located approximately 12 microns in the narrow direction down from the upper surface. The local shear rate is estimated to be 100 inverse seconds. A dilute suspension of beads and a 25% suspension (volume/volume) of erythrocytes was used. Values that were measured compared well with those predicted by the Stokes-Einstein equation and with published data for blood flows.
Effects of Stenosis Asymmetry on Blood Flow in Stenotic Arteries and Wall Compression
Authors: Tang Dalin , Yang Chun , Huan Zhongdan , Ku David N.
Published: December 2021

Severe stenoses in arteries cause critical flow conditions which may be related to thrombus formation, artery compression and plaque cap rupture. The exact mechanism of these events and the conditions causing them are not well understood. Considerable work for flow in stenotic tubes have been reported in last twenty years and many interesting phenomena such as flow limitation, choking, flutter and wall collapse have been observed [3]. Stenosis severity, wall compliance and pressure conditions have been identified as dominating factors affecting wall deformation and flow and pressure fields. However, real arteries are rarely axisymmetric. Stenosis asymmetry may have considerable effects on wall stress and the critical flow characteristics.
Characterization of Photo-Oxidized Small Bore Grafts
Authors: Hern-Anderson Diane L. , Hernandez Anne Marie J. , Ranieri John P. , Weinberg Steven
Published: December 2021

Many have hypothesized that both chemical and mechanical material properties are important in the design of a small bore vascular graft. In an attempt to address both issues, a xenogeneic graft crosslinked by photo-oxidation and covalently modified with heparin was developed. The compliance, burst strength, and suture pull strength of photo-oxidized (PhotoFix®) and heparin-modified photo-oxidized ovine carotid tissue were tested in vitro. The heparin modification process was found to have no statistically significant effect on any of these properties. The shrink temperature of fresh, photo-oxidized, and heparin-modified photo-oxidized tissue was assessed using DSC. A small increase in the shrink temperature of the heparin-modified photo-oxidized tissue over the fresh tissue was found to be statistically significant (P < 0.05). In vivo assessment of unmodified, heparin-soaked, and heparin-modified PhotoFix ovine grafts indicated that covalent modification of the grafts was imperative for the graft’s success.
A Structural Constitutive Model for Chemically Treated Soft Tissues
Authors: Sacks Michael S.
Published: December 2021

Chemically treated biologically derived tissues are used extensively in bioprostheses. Unfortunately, while extensive research has focused on chemical treatment technologies to reduce negative in-vivo effects such as mineralization and to enhance overall biocompatiblity, little work has been done on understanding the effects of chemical treatment on tissue mechanical properties. In the current work, a structural constitutive model for chemically treated tissues is presented that seeks to separate out the effects of the chemically treated matrix from that of the collagen fibers. Experimental results from Sacks and Chuong (Sacks and Chuong 1998) using glutaraldehyde bovine pericardium (GLBP) are used to demonstrate the approach. A unique feature of the current approach is the integration of collagen fiber orientation data quantified by small angle light scattering (SALS).
ATP-Induced Ca2+ Signaling in Human Chondrons Cultured in 3-Dimensional Gels
Authors: Elfervig Michelle K. , Sood Ajay , Lee Greta , Graff Ron , Francke Eric , Banes Albert J.
Published: December 2021

Cell-cell communication allows for the coordination of biological functions. In this study, we found that chondrons increase their intracellular calcium concentration ([Ca2+]ic) upon stimulation by ATP at a 10μM concentration in resting and stimulated cells. Digital fluorescence microscopy was used to determine the [Ca2+]ic in resting and stimulated cells. Inhibition of signal propagation by the purinoceptor blocker, suramin, showed that ATP activates P2Y2 purinoceptors. We also found that chondrons signaled in a calcium-free medium showing that bound intracellular calcium is used in signal propagation. This study is the first to illustrate that chondrons in 3-D gels respond to the extracellular messenger molecule ATP by increasing their intracellular calcium concentration.
Alternative Pathways of Epidermal Growth Factor Receptor Mediated Contractile Force in NR6 Fibroblasts
Authors: Allen Fred D. , Asnes Clara F. , Wells Alan , Elson Elliot L. , Lauffenburger Douglas A.
Published: December 2021

We investigated the contractile force response to epidermal growth factor (EGF) stimulation in 3T3-derived NR6 fibroblast cells in order to determine significant pathways of biochemical signaling that mediate the response. We examined the force generating specificity of the EGF receptor (EGFR) signaling mechanism by using mutant NR6 fibroblasts expressing variations of the EGFR construct. The wild-type (WT) cell presented the complete internalizing EGFR signaling construct while the c’973 cell presented an internalization-defective EGFR construct, and the M721 cell presented a kinase-defective EGFR construct making it signaling inert. Additionally we examined the roles of the phospholipasc C-γ (PLCγ) pathway by using the PLC inhibitor U73122 (1 μM) and the mitogen activated protein kinase (MAPK) pathway using the inhibitor PD98059 (10 μM) in the observed contractile force responses. We found that the WT cells showed a rapid but transient force increase within the first hour post-stimulation and the c’973 showed a more gradual increase in force which it sustained for several hours post-stimulation. Blocking the PLCγ activation in the WT cells reduced the peak force increase by 50% while blocking MAPK did not affect the force development in either WT or c’973 cells.
The Role of Elastic and Large-Strain Mechanical Behavior on the Wear of UHMWPE, HDPE, PTFE, and Polyacetal Evaluated by a Hip Simulator
Authors: Edidin A. A. , Giddings V. L. , Kurtz S. M.
Published: December 2021

The elastic and large deformation mechanical behavior of four materials with known clinical performance was examined and correlated with the wear behavior in a hip simulator. Acetabular liners of a commercially-available design were machined from UHMWPE, HDPE, PTFE, and polyacetal and wear tested in a multidirectional hip joint simulator. Elastic and large-deformation mechanical behavior was directly measured from the wear-tested liners using the small punch test. The inverse finite element method was used to compute elastic modulus from the measured small punch test initial stiffness, and the contact stress for the liners was calculated using the theory of elasticity solution. Positive, statistically-significant correlations were observed between the hip simulator wear rate and the initial peak load, ultimate load, and work to failure from the small punch test. Negative correlations were observed between the wear rate and the elastic modulus and contact stress. This results of this study support the hypothesis that the large deformation mechanical behavior of a polymer plays a greater role in the wear mechanisms prevalent in total hip replacements than the elastic behavior.
Viscoelastic Behavior of UHMWPE TKR Components During Compressive Loading and Sliding Conditions
Authors: Rullkoetter Paul J.
Published: December 2021

Finite element stress analysis is frequently used to evaluate wear propensity in total joint replacement components. Previous work has primarily concentrated on static UHMWPE material properties and has not included important time-dependency. In this study, a viscoelastic material model was used to evaluate tibio-femoral contact stresses during simulated in vivo loading conditions of combined compressive load and femoral rotation and translation. After initial loading and displacement, the UHMWPE tibial component showed significant creep displacement and stress relaxation with constant load. These results demonstrate the importance of including time-dependent material behavior in assessing contact stresses in finite element analyses or experimental evaluation of TKR designs. The material recovery after initial indentation is slow enough to allow continued femoral articulation over newly created ridges on the edge of contact, and this effect may play a role in tibial component wear and damage.
3D Nonlinear Finite Element Analysis of Knee Joint Implants
Authors: Hashemi A. , Shirazi-Adl A.
Published: December 2021

The finite element (FE) method has been used in orthopaedic biomechanics to investigate the fixation role of different design parameters in total knee replacement (TKA). Previous FE model studies used 2D, axisymmetric and 3D models to represent the geometry while neglecting many essential features. They simulated the bone-implant interface as frictionless, perfectly bonded or with idealized Coulomb’s friction model. The model of screws and posts have also been neglected altogether or inadequately considered in these studies. To overcome these limitations, the objective of the present study was set to develop a detailed 3D FE model of the knee bone-implant structure including all the interacting components in an immediate postoperative period without bony ingrowth to predict the micromotion at the bone-implant interface and stress distribution within the bone and the polyethylene insert.
An Improved In Vivo Rat Tail Vertebra Model for the Study of Trabecular Bone Adaptation
Authors: Eichler Mark J. , Kim Chi Hyun , Guo X. Edward
Published: December 2021

The role of mechanical loading in trabecular bone adaptation is important for the understanding of bone integrity in different loading scenarios such as microgravity and for the etiology of age-related bone fractures. There have been numerous in vivo animal studies of bone adaptation, most of which are related to cortical bone remodeling, aimed at the investigation of Wolff’s Law [4], An interesting experimental model for trabecular bone adaptation has been developed in the rat tail vertebrae [2,3]. This model is attractive for trabecular bone adaptation studies because a controlled mechanical load can be applied to a whole vertebra with minimal surgical trauma, using a relatively inexpensive animal model. In addition, with advanced micro computed tomography (micro-CT) or micro magnetic resonance imaging (micro-MRI) coupled with large scale finite element modeling techniques, it is possible to characterize the three-dimensional (3D) stress/strain environment in the bone tissue close to a cellular level (∼25μm) [1]. Therefore, this in vivo rat tail model has a tremendous potential for quantification of the relationship between mechanical stimulation and biological response in trabecular bone adaptation.
The Influence of Cartilage Thickness in the Multibody Modeling of Patellofemoral Joint Kinematics and Contact Stresses
Authors: Cohen Zohara A. , Ateshian Gerard A.
Published: December 2021

Three dimensional multibody computer models have been recently used to analyze the kinematics of the patellofemoral joint (PFJ) of patients with osteoarthritis (OA) (Cohen, et al., 1998). By employing cartilage specific magnetic resonance images (MRI) to acquire the model geometry, detailed topographies of the cartilage surfaces were obtained to model the contact between the opposing surfaces of the patella and femur. Contact stresses due to compression of the cartilage layers were approximated by a linear function of the compressive strain estimated from the relative change in cartilage thickness within the contact region. In our earlier studies, a uniform cartilage layer thickness was assumed in the analysis of joint contact, and a validation of this model was performed by comparing its kinematic predictions to the measured kinematics of five cadaver joints (Kwak, et al., 1996).
Is Articular Cartilage Orthotropic in Compression?
Authors: Soltz Michael A. , Mauck Robert L. , Hung Clark T. , Ateshian Gerard A.
Published: December 2021

Many studies have demonstrated that articular cartilage is anisotropic in tension, based on tensile tests of tissue strips harvested parallel to the articular surface, along and perpendicular to the local split line direction (e.g., Akizuki et al., 1986; Kempson et al., 1968; Schmidt et al., 1990; Woo et al., 1979). The observed differences in the tensile modulus suggest that the material symmetry of cartilage in tension is no higher than orthotropy, since two orthogonal planes of symmetry (with unit normals parallel and perpendicular to the split line direction) automatically define a third plane of symmetry mutually perpendicular to the other two. However, the properties of articular cartilage differ significantly in tension and compression (Cohen et al., 1998; Soulhat et al., 1998) and it remains to be established whether cartilage is anisotropic in compression as well. Only one previous preliminary study has investigated the compressive modulus of cartilage along two mutually perpendicular directions (Jurvelin et al., 1996), reporting significant differences.
Finite Element Contact Analysis of a Cartilage Layer Exhibiting Tension-Compression Nonlinearity
Authors: Ateshian Gerard A. , Soltz Michael A.
Published: December 2021

Experimental studies have demonstrated that the moduli of articular cartilage in compression are one to two orders of magnitude smaller than in tension. However, only a few analyses of cartilage mechanics have been performed which account for this tension-compression nonlinearity (Soulhat et al., 1998; Ateshian and Soltz, 1999a,b). In order to understand the state of stress under loading conditions which simulate the physiologic environment of diarthrodial joints, and the possible implications for tissue failure and the pathomechanics of osteoarthritis, it is important to determine whether the tension-compression nonlinearity of cartilage significantly affects our current understanding of its response in contact mechanics. Most analyses of cartilage contact have employed linear isotropic or transversely isotropic models for cartilage, either within the context of elasticity theory or porous media theories. In this study, we present a finite element solution for the contact of a rigid spherical impermeable sphere against a cartilage layer supported on a rigid impermeable subchondral bone foundation, where cartilage is modeled using our recently proposed biphasic conewise linear elasticity model (Ateshian and Soltz, 1999a,b). A comparison is also provided with the more frequently used linear isotropic biphasic model, under similar conditions.
Permeability of Human Glenohumeral Joint Cartilage
Authors: Stankiewicz Anna , Ateshian Gerard A. , Bigliani Louis U. , Mow Van C.
Published: December 2021

The nearly frictionless lubrication in diarthrodial joints and load support within articular cartilage depends on its mechanical properties. It has been shown that the majority of applied loads on cartilage are supported by interstitial fluid pressurization (Ateshian et al., 1994) which results from the frictional drag of flow through the porous permeable solid matrix. The duration and magnitude of this pressurization are a function of the permeability of cartilage (Lai et al., 1981).
Intervertebral Disc Morphology in Cervical Spine Biomechanics
Authors: Kumaresan Srirangam , Pintar Frank A. , Yoganandan Narayan , Khouphongsy Phaladone J. , Cusick Joseph F.
Published: December 2021

Although qualitative descriptions of degenerative changes in the intervertebral disc components have been reported, methods to quantify these changes are lacking. A methodology was developed in this study to quantify the three-dimensional geometrical variations of the annulus fibrosus and nucleus pulposus. Fresh isolated intervertebral discs with adjacent vertebral bodies of skeletally mature young and old adult primates were sectioned sequentially, and different staining methods were used to distinguish the annulus and nucleus. Histological images were examined using light microscopy and exported to a computer to trace the boundaries of the annulus fibrosus and nucleus pulposus. Dorsal to ventral depth, medial to lateral width, and caudal to cranial height measurements of the nucleus pulposus and its relative location to the annulus pulposus were obtained. In the young adult, the nucleus was translucent with scattered notochordal cells. In the older adult, the nucleus appeared as a dense region of amorphous, irregular collagen material. A higher geometrical variation of nucleus due to degeneration was noted in the sagittal plane compared to coronal plane. Determination of the three-dimensional geometrical variations and histology analyses will assist mathematical modelers to better define the disc to study the biomechanics of the cervical spine.
A Finite Element Analysis of a Healthy Middle-Ear and a Middle-Ear Reconstructed With Prostheses
Authors: Prendergast Patrick J. , Rice Henry J. , Blayney Alexander W.
Published: December 2021

The human car is a complex biomechanical arrangement of bones and soft-tissues. To sense a sound, the pressure wave enters the ear canal (a curved tube) and is transformed as it travels towards the tympanic membrane (or ear drum). The tympanic membrane vibrates causing motion of the three bones of the middle-ear: the malleus, incus, and stapes (commonly called the hammer, anvil, and stirrup). The stapes motion stimulates the perilymph fluid of the inner-ear leading to an electrical pulse to the brain allowing us to perceive sounds. The there bones (called the ossicles) are suspended from the surrounding bone by various ligaments.

Replacement of the ossicles with a prosthesis is a common surgical procedure, though it is not entirely satisfactory because the prosthesis can loosen or even extrude out from the middle-ear. In this study, we have developed an FE model of the healthy middle-ear and compared its vibro-acoustic response with the middle-ear reconstructed with two types of prosthesis — a partial ossicular replacement prosthesis (PORP) and a total ossicular replacement prosthesis (TORP).
Stress Analysis at Cervical Region of Human Teeth
Authors: Chang Chih-Han , Lin Chun-Li , Wang Chau-Hsiang , Lee Huey-Er
Published: December 2021

The concept of stress-induced cervical lesions has been discussed widely in recent years. In this study, a three-dimensional finite element model was established to analyze the stress distribution at cervical region and evaluate the stresses on the interface of different restorative materials. The results indicated that tensile stress might be the major cause for tooth cervical lesion. For different restorative materials, the elastic modulus was not the key issue in premature loss of restorative material. The bonding strength between the restorative material and lesions could be the important factor for the retention failure.