bluuebunny/crossref_metadata_2025 huggingface dataset:
Crash Test Software Analysis
Authors: Harrison Justin F. , Radu Ionut , Babcock Alan J. , Todd Beth A.
Published: June 2008

The development of highly advanced computer simulation software packages has enabled design engineers to more effectively integrate safety features into their designs. Designs can be tested long before any physical construction ever begins. This saves money, allowing more extensive testing to be performed, and it also saves time, expediting the process of moving concept to reality. In the automotive industry, such software can be especially useful, since computer simulations can be run over and over again, making it possible to observe the effects of adjusting single variables in dynamic situations. This has opened the door for testing of non-typical occupants. Restraints and safety devices are no longer designed to suit the needs of the average person; they can be tailored to account for all body types, or even for the disabled.
Biomechanical Analysis of Soft Tissue Neck Injury During Pedestrian Fall
Authors: Sances Anthony , Kumaresan Srirangam
Published: June 2008

Pedestrians sustain serious injuries when impacted by vehicles [1]. Various biomechanical studies have focused on pedestrian injuries due to direct contact with the vehicle and environment [1–5]. Similar studies on the injuries to the pedestrian due to indirect force such as inertial load are limited [6]. One of the most susceptible regions of the human body to inertial loading is the neck component (cervical spine). The cervical spine connects the head and upper torso, and provides mobility to the head. Direct loading to the head and/or upper torso subjects the cervical spine to indirect loading. For example, in a pedestrian lateral fall on the shoulder, the cervical spine flexes laterally due to inertial loading from the head and upper torso, and may injure its soft tissue components. The purpose of this study is to delineate the biomechanics of the soft tissue neck injury during the pedestrian lateral fall due to vehicular impact using the anthropometric test device.
Biodynamics of Stand-Up Rider Lift Truck Accidents
Authors: Zoghi-Moghadam Mohamad , Sadegh Ali , Watkins Charles , Dunlap Dan
Published: June 2008

This paper describes testing and simulation of operator and truck kinematics during stand-up rider forklift truck accidents. A Hybrid III, ATD was used as an operator surrogate and tested in an off-the-dock accident experiment. A rigid multibody, biomechanical model, representing the ATD, was developed and validated with deceleration sled data. The biomechanical model was then used with a truck model in a simulation of the test. The kinematic results are in agreement with the testing. Various physical and initial conditions of the truck and biomechanical model were studied.
Use of Upper and Lower Neck Load Cell Data From the Hybrid III Dummy to Assess Whiplash Injury Risk
Authors: Voo Liming , Kleinberger Michael , Merkle Andrew
Published: June 2008

Whiplash associated disorders (WAD) of the neck continue to represent a significant societal problem with associated costs estimated at over $5 billion annually. Recent dramatic increases in whiplash-related research has produced some interesting new findings related to its injury mechanism. It has been shown in human volunteer and cadaver experiments that the human head-neck structure often exhibits a transient S-shape during the initial kinematic response (Grauer et al. 1997; Luan et al. 2000; Ono et al. 1997; Yoganandan et al. 1998). Such a finding has significant impact on the injury risk assessment using the instrumented anthropomorphic test dummies in vehicular or sled testing. Unlike the recently developed dummy necks for rear impact testing, such as BioRID and TRID, the Hybrid III neck does not exhibit an S-shape curvature or the so-call “retraction” motion in rear impact testing. Numerous studies have reported that the Hybrid III neck is too stiff for low-speed rear impact testing (Svensson et al. 2000; Yoshida and Tsutsumi, 2001). Nevertheless, the Hybrid III is still being used for motor vehicle safety evaluation in rear impact as it is the only dummy neck that has been incorporated in the US Federal Motor Vehicle Safety Standards (FMVSS).
Monte Carlo Simulation of Ice Formation in Tissues
Authors: Irimia Daniel , Karlsson Jens O. M.
Published: June 2008

Freezing is a common technique for preservation of isolated cells, and extending its applications to the preservation of tissues would have important implications for the storage and distribution of tissue engineered products. Unlike isolated cells in suspension, cells in tissue interact with each other, and this interaction is known to affect the outcome of tissue cryopreservation. As a consequence, our knowledge of the cryobiology of isolated cells cannot simply be extrapolated to tissues, and new models, which consider the interaction between cells, need to be developed. The model that we propose is based on previous quantitative analysis of intercellular ice propagation in a micropatterned two-cell system. We used Monte Carlo simulations to extrapolate the results from cell pairs to two-dimensional and three-dimensional tissues. Effects of tissue geometry, cellular connectivity, and degree of intercellular interaction were investigated.
Attenuation of High Amplitude Vibrations With Particle Dampers
Authors: Yang Michael Y. , Koopmann Gary H. , Lesieutre George A. , Hambric Stephen A.
Published: June 2008

Fluid transport systems are rarely at steady state. Transient phenomena, such as water hammer, can inflict severe physical damage. Repair costs can soar into the millions of dollars (Myers, 1997), and can reduce or even halt operation. Such high amplitude vibrations may be attenuated with particle dampers, which are beds of small particles placed in an attached enclosure or contained void. Vibration of the enclosure causes the particles to collide with each other and with the enclosure walls, resulting in energy dissipation through inelastic impacts and friction. Particle dampers have many advantages over conventional viscoelastic treatments including lower cost, increased robustness, greater effectiveness at high amplitudes and the ability to operate in extreme-temperature environments. Previous papers focus on exploration of sensitivity to design parameters, modeling techniques, and effective applications. However, there still remains much that is unknown about the phenomena and design of particle dampers. In this paper, experiments were performed to explore the effects of friction, excitation amplitude, and particle gap size. The formation of an oily residue on the colliding surfaces when certain materials were used increased friction and reduced damper effectiveness. This agrees with the theoretical prediction made by Mansour and Filho (1974). Damping was found to peak at an optimum gap size. Increasing the excitation amplitude resulted in higher damping and reduced sensitivity to the optimum gap size. Overall, the particle damper was deemed to be successful, increasing the loss factor of a clamped beam by over 10 times with a damper/structure mass ratio of only 0.016.
Vibration Analysis of Steam Generators and Heat Exchangers: An Overview — Part I: Flow, Damping, Fluidelastic Instability
Authors: Pettigrew Michel J. , Taylor Colette E.
Published: June 2008

Design guidelines were developed to prevent tube failures due to excessive flow-induced vibration in shell-and-tube heat exchangers. An overview of vibration analysis procedures and recommended design guidelines is presented in this paper. This paper pertains to liquid, gas and two-phase heat exchangers such as nuclear steam generators, reboilers, coolers, service water heat exchangers, condensers, and moisture-separator-reheaters. Generally, a heat exchanger vibration analysis consists of the following steps: 1) flow distribution calculations, 2) dynamic parameter evaluation (i.e. damping, effective tube mass, and dynamic stiffness), 3) formulation of vibration excitation mechanisms, 4) vibration response prediction, and 5) resulting damage assessment (i.e., comparison against allowables). The requirements applicable to each step are outlined in this paper. Part 1 of this paper covers flow calculations, dynumic parameters and fluidelastic instability.
Novel Lithography-Based Approaches to Pattern Layer-by-Layer Self-Assembled Thin Films
Authors: Cui Tianhong , Lvov Yuri , Hua Feng , Shi Jingshi
Published: June 2008

Layer-by-layer self-assembly is a key enabling technique in nanotechnology. It is very crucial to pattern the self-assembled thin films for the realization of nano/microelectronics devices or NEMS (Nano Electro Mechanical Systems). Two approaches to generate spatially separated patterns comprised of organic or inorganic nanoparticles are demonstrated. The processes are based on the lithographic patterning of the nanoparticle-based thin films which are layer-by-layer assembled. This opens to industrial applications of popular layer-by-layer method to produce multilayers for polymers, nanoparticles and protein organized in nanometer scale. These two methods are referred to by us as “lift-off” and “metal mask”, respectively. Sharp and clear patterns are created with both methods and images are recorded by scanning electron microscope. Their advantages and disadvantages are discussed and potential usage in 3-D nanostructure fabrication is investigated. In addition, temperature-dependent experiment has first been carried out to make this techniques more practical for micro/naoelectronics or NEMS devices.
Simulation and Fabrication of Novel Polymeric Tunneling Sensor by Hot Embossing Technique
Authors: Cui Tianhong , Varahramyan Kody , Zhao Yongjun , Wang Jing
Published: June 2008

This paper reports the simulation and fabrication of novel polymer-based tunneling sensors by hot embossing technique, one of the advanced polymer microfabrication technologies. ANSYS is the software tools used to simulate the mechanical microstructures of the polymer tunneling sensors. Following the optimum design of the sensors, the mold inserts of hot embossing are fabricated by anodic bonding of glass disk 5 mm think and silicon wafer, with high-aspect-ratio microstructures by ICP etching. Main structures of polymer-based tunneling sensors are hot embossed on PMMA, followed by plastic bonding to form lateral tunneling sensor platform.
Failure Strength Distribution in Abdominal Aortic Aneurysm: A Necropsy Study
Authors: Raghavan Madhavan L. , Ikeda Marcos H. , da Silva Erasmo S.
Published: June 2008

Knowledge of the inherent ability of an abdominal aortic aneurysm (AAA) wall to withstand stress — its failure properties — is vital to understanding aneurysm rupture. Given its known heterogeneity, it is conceivable that the failure strength varies regionally within an AAA. Previous reports on failure strength of aneurysmal tissue have confined to specimens obtained from a few select locations (anterior-midsection, mostly). In this work, four AAAs were harvested as a whole from autopsies. From each AAA, numerous specimen strips located at various regions were extracted. The failure tension for each strip was determined by subjecting them to uniaxial extension tests and compiled to study how failure properties are regionally distributed.
Development of Anisotropy in Fibroblast Populated Collagen Gels
Authors: Thomopoulos Stavros , Knezevic Vedran , Costa Kevin D. , Holmes Jeffrey W.
Published: June 2008

The development of anisotropic mechanical properties is critical for the successful tissue engineering of many soft tissues. Load bearing tissues naturally develop varying degrees of anisotropy, presumably in response to their specific loading environment. For example, the heart wall develops a collagen structure that varies in a predictable manner through its depth [1]. Tendon, on the other hand, develops a matrix that does not vary much in orientation and is highly aligned in the direction of muscle loading [2]. These varied levels of anisotropy may be due to inherent differences between the cells in each tissue, to differences in the mechanical load and boundary conditions seen by the cells, or to a combination of these factors.
Graft Healing of Stretched ePTFE Implanted Within a Baboon Model
Authors: Costello James R. , Chen Changyi , Giddens Don P. , Hanson Stephen R.
Published: June 2008

Arterial grafts need to exhibit two properties: a flow surface with low thrombogenicity and minimal intimal thickening. For well over thirty years, researchers focused their attention upon the healing properties of graft material. Beginning with Wesolowski’s 1961 work, researchers concluded that porous synthetic grafts demonstrated improved healing properties (1). Most recently, Clowes, et al., documented that ePTFE with a nominal porosity of 60μm healed atone month with complete endothelial coverage, uniformly distributed pseudointimal growth, and improved intimal stability (2). These results contrasted to what was found when porosity was deceased to an internodal distance of 10 or 30 μm.
Cell Adhesion and Deformation Under Dynamic Shear Flow in a Micro-Channel
Authors: Xu J. , Zhang H.
Published: June 2008

Progress has been made in the area of cell-fluid interaction considering deformation, adhesion, and rolling in a shear flow, for example, the seminal work of Dembo and colleagues [1]. Several other studies have also performed to provide a better understanding on the phenomena [2–4]. The dynamics of fluid flow and cell deformation add complexity to the complicated adhesion interaction problem. The objective of this study has aimed on developing a biomechanical model that can be used to predict the cell-endothelium interaction under the transient flow condition. To elucidate the roles of flow force, adhesion force, adhesion interaction, and cell deformation in leukocyte rolling under a shear flow, a model combining fluid-cell interaction and reaction-limited cell-substrate adhesion kinetics has been developed. In this paper, the cell is modeled as an elastic solid and fluid-cell interaction is modeled as the fluid-solid interaction.
Fluidelastic and Vortex Induced Vibration of a Finned Tube Array
Authors: Hirota Kazuo , Nakamura Tomomichi , Kikuchi Hirohiko , Isozaki Kazunori , Kawahara Hirotaka
Published: June 2008

Fluidelastic and vortex induced vibration are important problems in operating heat exchangers. Many studies have been conducted to solve the problems. As a result, design guideline has already existed for the flow-induced vibration of a tube bundle. On the other hand, some kinds of heat exchanger use finned tube array in order to improve the efficiency of the heat transfer. For finned tube array, some studies for vortex induced acoustic resonance have been conducted, where Strouhal numbers are obtained. However fluctuating lift coefficients due to vortex are important from the viewpoint of tube vibration. Moreover, critical velocities for fluidelastic vibration are also important. In this study, fluidelastic and vortex induced vibration tests were conducted for a triangular finned tube array. Two different frequencies of the vortex shedding were observed. For this tube array, Strouhal numbers were 0.13–0.15, 0.37–0.39. However vortex induced forces were too weak to excite the finned tubes. For this tube array, averaged Connors’ constant K was 6.8.
Locomotive Crashworthiness Testing at the Transportation Technology Center
Authors: Brickle Barrie V. , Spons Gunars
Published: June 2008

This paper describes a series of full-scale impact tests to be conducted at the Federal Railroad Administration’s Transportation Technology Center (TTC), Pueblo, Colorado. The tests will be performed to investigate locomotive crashworthiness.
Design of Microcantilever for a Biosensor
Authors: Kang Ji-Yoon , Kim Hyung-Jun , Kim Tae-Song
Published: June 2008

We analyzed the dynamic characteristics of cantilever biosensor for the detection of disease using antibody-antigen reaction. We suggested a design guide to detect the mass of protein. The length of cantilever is the major factor among shape dimensions to affect the mass resolution and it should get smaller for the better accuracy. However this mass detection model does not explain all the experimental results, therefore we adopted the beam equation with tension. Adding the effect of tension on the shift of resonance frequency, the experimental results could be explained.
Hydrodynamically Coupled Vibration of Shell With Liquid and Rod Bundles
Authors: Fedotovsky Vladimir S. , Vereshchagina Tatiana N. , Efanov Aleksandr D.
Published: June 2008

The conception of effective vibrodynamic properties of heterogeneous media is presented, enabling one to solve various problems on vibration of elastic systems containing liquid and a large number of identical inclusions. The idea of the conception consists in that the liquid with the inclusions (for example, a rod bundle) being affected by vibration is considered a continuous medium with the special dynamic properties – vibrodensity and vibroviscosity. These properties are dependent both on the properties of liquid and inclusions and on the frequency of vibration impacts. It is these vibrodynamic properties upon which the vibration performance of elastic systems containing heterogeneous media is dependent. General equations of vibrodensity and vibroviscosity are used in studying natural and forced vibrations of shell containing liquid and a bundle of elastic rods. It is established that natural frequencies and amplitudes of shell resonance vibrations depend on rod bundle parameters. The result obtained on vibrodensity was used as well for determination of natural frequencies of free-surfacc liquid vibration in cylindrical vessel enclosing rod bundle. It is demonstrated that the natural frequencies of liquid vibration in vessel with rod bundle are lower than in vessel without rods. Comparison of theory with experimental data is made.
Flow Induced Vibration and Fretting Wear: An Integrated Approach
Authors: Paramonov D. V. , King S. J. , Young M. Y. , Lu R. Y.
Published: June 2008

Fuel assemblies are exposed to severe thermal, mechanical and radiation loads during operation. Global core and local fuel assembly flow fields typically result in fuel rod vibration. Under certain conditions, this vibration, when coupled with other factors, might result in excessive cladding fretting wear. This phenomenon is of the concern for nuclear fuel designers, especially in light of the need for higher burnup, longer cycle lengths, and operational safety margins in fuel designs. Understanding of (1) the fretting wear margins for a particular nuclear fuel design, (2) the probability of a fuel assembly exposed to a particular set of thermal, mechanical, flow and radiation conditions being at risk of excessive wear, and (3) the factors affecting fretting wear resistance, are important in order to better guide design, testing, and operational flexibility. In this paper, an integrated method to estimate fretting margin of nuclear fuel is presented, including its formulation, benchmark against experimental data and example application to in-core conditions. The major features of the method are as follows: • flow and rod vibration response are coupled through a linear structural analysis model, • flow field is determined using a sub-channel thermal-hydraulic code, • wear progression is treated as a time-dependent process, through taking into account impact of resulting rod-to-support clearance, • a possibility of a fluid-elastic instability is accounted for. Supporting data on basic wear mechanisms, flow field and fuel assembly fretting wear behavior obtained at a number of experimental facilities at Westinghouse Electric Company and Atomic Energy of Canada Limited are also presented. These facility include: • VIPER hydraulic test loop data where vibration response and wear are measured under prototypical flow conditions, and • autoclave fretting-wear machine steam employed to determine fretting-wear coefficients of fuel rod and grid-support designs.
Measurement Scheme Synthesis in Multi-Station Machining Systems
Authors: Djurdjanovic Dragan , Ni Jun
Published: June 2008

The selection of measurements in multi-station machining systems is currently not a systematic process and it involves expert human intervention. In this paper, the recently introduced formal methods for quantitative characterization of measurement schemes in multi-station machining systems are employed in devising systematic measurement scheme synthesis procedures. The newly proposed synthesis procedures were applied in devising measurement schemes in the process used to machine a car engine cylinder head. It was observed that the measurement scheme synthesis procedure based on a genetic algorithm robustly outperformed the synthesis procedures based on the heuristics of successive measurement removal.
A New Methodology for Sensor Selection in Process Monitoring of Reconfigurable Machining Systems (RmSs)
Authors: Mehrabi Mostafa G. , Kannatey-Asibu Elijah
Published: June 2008

This article outlines a new approach for selecting an appropriate monitoring system for any given machining system. Presented are the concepts of fault, sensor, signal processing and computing spaces and their generic characteristics. Study of their fundamental properties reveals that there are certain levels of uncertainty involved in describing them. This has led us to the adoption of fuzzy systems theory as a fundamental tool for development of the “Mapping Theory”. It is shown that based on the characteristics of the faults and the type of machining operations, it is possible to rank the sensors based on their characteristics and to come up with an appropriate multi-sensor monitoring system. Examples are provided to show the effectiveness of the approach.
Cost Drivers in Microlamination Based on a High-Volume Production System Design
Authors: Porter J. David , Paul Brian K. , Ryuh Beom-Sahng
Published: June 2008

The purpose of this research is to develop a cost estimation model in an attempt to begin exploring the current cost drivers for microlamination. To do this without actual cost information, a production system design is proposed for the high-volume production of MECS devices. Constraints on this facility are that it produces microlaminated structures from stainless steel diffusion bonding. Also, a cost estimation model is developed based on the known cycle time and capital equipment costs from the production system design. Finally, a sensitivity analysis is performed to determine the cost drivers under different market and product scenarios. Results from the sensitivity analysis indicated that device size and production rate do have an effect on the overall manufacturing cost of microlamination devices. Therefore, it is concluded that the emphasis of future research in metallic microlamination should focus on bonding larger laminae and in reducing both cycle time and warpage.
Crashworthiness of Aircraft Composites Structures (Invited Talk)
Authors: Arnaudeau F. , Mahe´ M. , Deletombe E. , Le Page F.
Published: June 2008

More and more aircraft components are made of fiber reinforced composite material because of high stiffness, strength and low weight. These composites are made of glass or carbon fibers embedded into a polymer matrix. In some case, for equivalent energy absorption, composite components can be 50% lighter than steel components. The resistance of aircraft composite components to impact of various debris or birds must be assessed. Extensive literature exists describing the energy absorption mechanism of composite laminate tubes crushed between two rigid plates. Triggers are usually used to initiate material peeling inside and outside of the tube. The energy is absorbed by more complex mechanisms than for metallic tubes, such as delamination, fibers debonding, pulverization of material and friction. A constitutive model using damage mechanics is described in this paper. The model has been validated on composite tube crushing. This paper also describes the numerical results obtained with RADIOSS for the crash of composite sine wave beam and of sub cargo floor structure. Bird strike simulation results are also shown in the case of impact on a commuter leading edge structure. Comparison with tests results is shown. RADIOSS is an explicit finite element code developed by MECALOG, used for non linear simulations and validated industrially for crash analysis of metallic structures in automotive and aeronautic applications.
Axial and Lateral Impact Prediction of Composite Structures Using Explicit Finite Element Analysis
Authors: Caliskan Ari G.
Published: June 2008

The use of composite materials in the automotive industry is growing since these materials exhibit high stiffness, strength and low weight. As such, analytical capabilities must be developed in order for these materials to be used in more structural applications. Previous work in the area of crush performance has concentrated on experimental and empirical studies that have qualitatively characterized the crush process. These studies have shown that the crush process in composite materials is complex, and is dominated by fiber/matrix microcracking, which is the main energy absorption mechanism. In this study, the crush performance of a set of tubular composite structures were modeled using the explicit code RADIOSS™. Unlike many of the other commercially available codes, the composite material model within RADIOSS uses material input parameters that can be easily extracted from basic material test. These tests would include a 0° and 90° tensile and compressive test, as well as an in-plane shear test. The model can also accommodate strain rate effects. As the structure is loaded, the stresses within each element and ply are calculated. Using a Tsai-Wu failure criterion, the material fracture is simulated by removing a failed ply within a given element. As a consequence, the material degradation within and ahead of the crush front is simulated. The results of the study showed that the steady state crush load could be predicted accurately. However, the exact failure mode with the crushed structure was not as accurately represented in the model. In addition, two other case studies one being a 3-point bending on a hexagonal section and composite sandwich plate impact analysis were also performed. The results showed good agreement with experiments in both load levels and failure modes.
Static and Dynamic Crush Behavior of Circular Aluminum Extrusions With Rigid PU Foam Filler
Authors: Maaita Salamah Y. , Newaz Golam M.
Published: June 2008

This paper introduces a new technique to increase the specific energy absorption (SEA) for foam-filled circular aluminum tube significantly. The idea is to first utilize initiators to deform the foam inside an aluminum tube under the effects of constraints of the tube wall. Then the aluminum tube and foam are crushed together. In this study, the foam with 190mm length has been filled inside a 200mm aluminum tube and attached to two 50 mm length initiators (one initiator in each side of the tube). Initially, the foam-filled tube has been compressed a total of 90mm by entering and sliding the two initiators inside the aluminum tube. Then the foam, two initiators and the aluminum tube have been compressed together for another 30 mm (The total crushing distance is 120mm). The technique was utilized under quasi-static and dynamic axial compression loading conditions and is found to increase the specific energy absorption (SEA) for the foam-filled circular aluminum tube up to 30% more compared to pure aluminum tubes for quasi-static and dynamic axial compression loading conditions. Both experimental and analytical/computational results are presented.
Eliminating the Unwanted Dynamics From the Controllable Suspensions for Vehicle Applications
Authors: Song Xubin , Ahmadian Mehdi , Southward Steve C.
Published: June 2008

This paper presents two alternative implementations of skyhook control, named “skyhook function” and “no-jerk skyhook,” for reducing the dynamic jerk that is often experienced with conventional skyhook control in semiactive suspension systems. An analysis of the relationship between the absolute velocity of the sprung mass and the relative velocity across the suspension are used to show the damping force discontinuities that result from the conventional implementation of skyhook control. This analysis shows that at zero crossings of the relative velocity, conventional skyhook introduces a sharp increase (jump) in damping force, which, in turn, causes a jump in sprung mass acceleration. This acceleration jump, or jerk, causes a significant reduction in isolation benefits that can be offered by skyhook suspensions. The alternative implementations of skyhook control included in this study offer modifications to the formulation of conventional skyhook control such that the damping force jumps are eliminated. The alternative policies are compared with the conventional skyhook control, using a laboratory implementation on a heavy truck seat suspension that represents a base-excited system with a semiactive suspension. An evaluation of the damping force, seat acceleration, and the electrical currents supplied to a magneto-rheological (MR) damper that is used for this study, shows that the alternative implementations of skyhook control can entirely eliminate the damping force discontinuities and the resulting dynamic jerks caused by conventional skyhook control.
Gas Cluster Ion Beam Polishing of Orthopedic Implants
Authors: DiFilippo Vincent , Saigal Anil , Zide Barry M.
Published: June 2008

One of the major causes of failure of orthopedic implants used in hip replacement surgery is the generation of excessive wear particles. These wear particles accumulate in the joint and initiate an autoimmune reaction which can weaken the bone-implant joint, leading to failure and revision surgery. The relatively poor implant surface finish created by current mechanical polishing techniques has been identified as a major cause of wear particle generation. Gas cluster ion beams (GCIB) have been successfully used to reduce the surface roughness of orthopedic implants. In GCIB, a high-pressure gas, such as argon, is supersonically expanded through a nozzle into vacuum. This adiabatic expansion results in the condensation of clusters consisting of tens to thousands of gas atoms weakly held together by Van der Waals forces. These clusters are then ionized and accelerated towards the target substrate. Upon impact, they create a strong lateral sputtering effect resulting in a net smoothing of the surface. Lapped flat coupons and production femoral balls made of ASTM 1537 cobalt-28 chromium-6 molybdenum surgical implant alloy were processed by GCIB utilizing gas clusters of argon and oxygen. Surface morphology was characterized before and after processing by atomic force microscopy and white light optical profilometry. As shown in Figure 1 GCIB processing was able to successfully remove asperities and create a tribologically improved surface on both flat test coupons and on production components.
Shape Optimization of Femoral Components of an Artificial Hip Prosthesis Using the Three-Dimensional P-Version Finite Element Study and the In Vitro Measurement of Strain in the Bone Cement
Authors: Higa Masaru , Nishimura Ikuya , Matsuda Kazuhiro , Tanino Hiromasa , Mitamura Yoshinori
Published: June 2008

Though Total Hip Arthroplasty (THA) is being performed with greater frequency every year for patients with endstage arthritis of hip, mechanical fatigue of bone cement leading to damage accumulation is implicated in the loosening of cemented hip components. This fatigue failure of bone cement has been reported to be the result of high tensile and shear stresses at the bone cement. The aim of this study is to design the optimum shape of femoral component of a THA that minimizes the peak stress value of maximum principal stress at the bone cement and to validate the FEM results by comparing numerical stress with experimental ones. The p-version three-dimensional Finite Element Method (FEM) combined with an optimization procedure was used to perform the shape optimization. Moreover the strain in the cement mantle surrounding the cemented femoral component of a THA was measured in vitro using strain gauges embedded within the cement mantle adjacent to the developed femoral stem to validate the optimization results of FEM.
Comparison of Subsidence Failure Between a Cervical Cage and a Cortical Allograft in a Human Cadaveric Model
Authors: DiAngelo Denis J. , Sharp Jason W. , McVay Bobby J. , Kitchel Scott H. , Kelly Brian P.
Published: June 2008

Interbody fusion (IBF) is an accepted procedure for the treatment of single-level cervical disc disease. The goal of interbody fusion in the cervical spine is to restore disc height and achieve solid arthrodesis; however, a concern with IBF devices is subsidence. The purpose of this study was to biomechanically test and compare subsidence between two cervical interbody fusion techniques, under axial compressive loading in a human cadaveric cervical model.
Effect of Extension Osteotomy of the 1st Metacarpal on Laxity of the Thumb Carpometacarpal Joint
Authors: Koff Matthew F. , Shrivastava Niket , Abbot Amy E. , Heyworth Benton E. , Gardner Thomas R. , Strauch Robert J. , Mow Van C.
Published: June 2008

Osteoarthritis (OA) of the human thumb carpometacarpal (CMC) joint is a debilitating disease. It has been proposed in the clinical literature that joint ligamentous laxity, or joint looseness, is a major etiological factor in OA of the CMC joint (Figure1) [1–4]. Previous investigations of laxity and stability of the human thumb CMC joint have been performed visually, with no quantitative measures of joint laxity recorded [5–7]. Surgical treatment has been a common solution to reduce the pain associated with CMC OA. One treatment, extension osteotomy of the 1st metacarpal, has been suggested not only to reduce the pain of OA, but also improve hand function [8], however, little is known about its biomechanical effects. A complete description of joint laxity requires that all physiological directions of motion be fully tested. A custom-designed, 4 degree of freedom tester was constructed and instrumented for displacement and load in the distraction-compression, dorsal-volar, pronation-supination, and radial-ulnar directions. The purpose of this study was to use this device to: 1) Measure the joint laxity and compliance of non-OA human thumb CMC joints and 2) Determine the effect that a simulated extension osteotomy has on joint laxity and joint stiffness. This study provides an accurate baseline for future comparisons with osteoarthritic, surgically corrected, and otherwise non-healthy CMC joints.
Simulation of Micro-Channel Flows by Parallel DSMC
Authors: Czerwinska Justyna , Fladrich Uwe
Published: June 2008

This paper is considering issues connected with parallelization of Direct Simulation Monte Carlo (later referred as DSMC). The method is applied to simulate gas flow in micro-channels. The general algorithm of DSMC can be divided into two steps: deterministic motion of particles and stochastic part, related to collisions of particles. This division also reflects in the way, how DSMC have to be parallelized. For the first part domain decomposition techniques are important, while the second step heavily depends on the parallel random number generator.
Active Control of Gear Noise Using Magnetic Bearings for Actuation
Authors: Johnson Marty , Kasarda Mary , Bash Travis
Published: June 2008

This paper investigates experimentally the active control of gear noise and vibration using magnetic bearing actuators in a feedforward active control scheme. The dynamic forces caused by gear meshing can produce large noise and vibration signatures that can cause annoyance and also fatigue mechanical components. In this work active magnetic bearings were used as actuators to introduce control forces very close to the source of the disturbance i.e. directly onto the rotating shaft. The proximity of the actuators to the source ensures that substantial control can be achieved using a small number of actuators. A four-square gear rig was constructed in order to test the control methodology experimentally. A proximity sensor placed near the gear teeth was used as a reference sensor and used to drive the two magnetic bearing actuators through a time domain filtered X-LMS control system to minimize the outputs from both vibration and pressure error sensors. At one microphone over 20 dB of reduction in acoustic levels was achieved at the gear mesh frequency and an overall reduction of 6 dB was demonstrated at four microphones. It is also shown that gear mesh noise and sideband frequencies can be simultaneously controlled.
Investigation of Contrast-Enhanced In-Vivo Animal Imaging With Micro-CT
Authors: Liang Yun , Stantz Keith M. , Krishnamurthi Ganapathy , Chen Laigao , Hutchins Gary D.
Published: June 2008

Rapid progress in molecular biology, much sparked by the human Genome Project, is opening a new era in medicine and biology. The development of in-vivo micro-imaging technology for small animals (mice and rats) has generated unprecedented opportunities for studying the structural and physiologic properties exhibited by different genes in a cost-effective and low-risk means. This knowledge, in turn, will help guide the study in human genetic system. Micro-computed tomograph (microCT) with resolution on the scale of micrometer is a new technique for obtaining the 3D images of the internal structure of small objects [1,2]. Its biological and medical applications include noninvasively screening animals for genetic mutations and identification as well as monitoring of structural and physiology properties that are linked with specific genes. This paper reports on our preliminary investigation on two aspects of this new imaging technique: (1) an initial experience of instrumentation capability and limitation, and (2) the contrast enhancement strategy necessary for organ-specific anatomic and physiologic studies.
Reduced-Order Modeling and Experiment for Turbomachinery Stall Flutter
Authors: Copeland George Scott , Rey Gonzalo J.
Published: June 2008

A reduced-order model for stall flutter of turbomachinery is presented. The model is based on simplified physics (actuator disk modeling of bladerows, typical section aeroelastic model) and the measured steady performance characteristic. The model is not intended to be predictive, though it has been shown to be “tunable” to stability measurements of the test rig. The objective of the effort is to estimate the relative sensitivity of flutter damping to system parameters. It is found that predictions are in good agreement with measured test rig data and industry experience.
An Investigation of the Aeroelastic Response of a Two-Dimensional, Structurally Nonlinear Airfoil Subject to External Excitation
Authors: Marsden Catharine C. , Price Stuart J.
Published: June 2008

The results of an analytical investigation are presented for the aeroelastic response of a two-dimensional, structurally nonlinear airfoil subject to a forced excitation. The system is modeled as a two-dimensional, rigid airfoil section free to move in both the bending and pitching directions and possessing a rigid flap. The airfoil is mounted by torsional and translational springs attached at the elastic axis, and the flap motion is used to provide the forcing input to the system. The airfoil is immersed in an aerodynamic flow environment, modeled using incompressible thin airfoil theory for unsteady oscillatory motion. The equations of motion for the aeroelastic system are solved using a fourth-order Runge-Kutta numerical integration technique to provide time-history solutions of the response of the airfoil in the pitch and plunge directions. The time-histories are analysed using Fourier transform-based techniques to obtain frequency-domain response and transfer functions. Results show that the nonlinear response of the aeroelastic system contains frequencies other than the forcing frequency. When modal frequencies and damping values are calculated using standard Fourier-based techniques, it is shown that the super- and sub-harmonic frequency content in the nonlinear response can contribute to errors when results are compared to those obtained for the equivalent linear system. This paper describes an investigation of a method of analysis that, while based on the Fourier transform, has been modified to recognize and accommodate the nonlinear contribution to the system response. The method, developed by Bendat [1], uses a band-limited random input and separates the linear and nonlinear components of the response within the frequency domain. Results are given for the application of this method to the specific case of the structurally nonlinear aeroelastic system. It is shown that the method may be used to successfully recover the linear frequency response function using the input and output data for the nonlinear system.
Nonlinear Aeroelastic Characteristics of a Fighter-Type Wing With Control Surface
Authors: Bae Jae-Sung , Lee In
Published: June 2008

The nonlinear aeroelastic characteristics of a fighter-type wing with control surface have been investigated. The fictitious mass modal approach is used to reduce the problem size and the computation time in the linear and nonlinear flutter analyses. A Doublet-Hybrid method are used for the computation of subsonic unsteady aerodynamic forces. Structural nonlinearity of the control surface hinge is represented by a free-play spring. The linear and nonlinear flutter analyses indicate that the flapping mode of control surface and the hinge stiffness have significant effects on the flutter characteristics. The nonlinear flutter analysis shows that limit cycle oscillation and chaotic motion are observed in the wide range of air speed below the linear flutter boundary and the jump of limit cycle oscillation amplitude is observed. The nonlinear flutter characteristics and the nonlinear flutter boundary of limit cycle oscillation and chaotic motion have been investigated.
Noise Transmission Control Studies on a Chamber Core Composite Cylinder
Authors: Li Deyu , Vipperman Jeffrey S.
Published: June 2008

The vibroacoustic behavior and sound transmission properties of a mock-scale chamber core composite cylinder were studied, and the feasibility of the active structural acoustic control and passive control was also investigated. A box-beam model of the chamber core cylindrical shell was used for calculating the critical frequency and the ring frequency. The coupling problems between structural and acoustic modes were investigated, and the structural and acoustic modal parameters were identified from measured data. The sound transmission into the chamber core cylindrical structure was measured with and without fill materials in its wall chambers. The structural stiffness-, cavity resonance-, coincidence-, and mass-controlled zones were identified and verified.
A Feasibility Study for Imaging Tissue Electroporation With Electrical Impedance Tomography
Authors: Davalos Rafael V. , Otten David M. , Mir Lluis M. , Rubinsky Boris
Published: June 2008

In tissue electroporation, electrodes are inserted around the targeted tissue and electrical pulses are applied to permeabilize the cell membrane to macromolecules such as gene constructs in genetic engineering or cancer treatment drugs [1, 2]. For a specific set of voltage parameters (e.g. pulse number, frequency, duration), the effect that the electric field has depends on the voltage gradients that develop across the individual cell [2].
Subgrid Particle-Fluid Coupling Evaluation in Large-Eddy Simulations of Particle-Laden Flows
Authors: Portela Lui´s M. , Oliemans Rene´ V. A.
Published: June 2008

Point-particle Eulerian-Lagrangian DNS/LES simulations allow us to deal with a large number of small particles, using relatively modest computer resources. When doing LES, one can consider the subgrid particle-fluid coupling, using a subgrid model, or simply ignore it. We present a criterion to evaluate the importance of the subgrid particle-fluid coupling on: (i) the particle motion, and (ii) the resolved fluid-motion. The criterion assumes that the particles can be treated as point-particles, from the perspective of both the resolved and subgrid motions, and it is based on simple “local equilibrium” models for the interaction between the particles and the subgrid fluid-motion. The criterion was applied to a high-resolution channel flow LES, with a moderate particle-loading. The results indicate that: (i) for heavy particles, the common practice of ignoring the subgrid particle-fluid coupling is adequate, (ii) for very-light particles a model for the subgrid-driven particle-velocity fluctuations might be important.
An Eulerian-Lagrangian Approach for the Numerical Simulation and Visualization of Two-Dimensional Fluidized Beds
Authors: Traore´ Ph. , Herbreteau C. , Bouard R.
Published: June 2008

This paper deals with an Eulerian-Lagrangian model for dispersed multiphase flow in which all the interactions of any kind are taking into account. The fluid phase and particles interactions are two way coupled while all the collisions between the particles or between the particles and the walls are calculated. The Navier-Stokes equations (fluid phase continuity and momentum equations including exchange from the particle to the fluid is modeled to simulate the effect of the presence of the particles in the fluid phase) are solved on a staggered Eulerian grid by a finite volume discretisation type method. The originality of the Lagrangian approach used here for the particles motion, lies in the way of managing the collisions which are calculated using simple mechanical models such as a spring, dashpot and friction slider at the contact points following the Distinct Element Method DEM [1]. In the Lagrangian stage, motion’s calculation of each discrete particle including collisions effects is generally time consuming. In the context of this paper we shall show how to optimized the contacts tracking algorithm in an efficient way to increase significantly the capability of the DEM.
Platelet Function Assessment in a Microfabricated Device
Authors: Kantak Ameya , Lvov Yuri , Mills David K. , Spaulding James G. , Jones Steven A.
Published: June 2008

Although platelets are small and simple in shape, they are complicated in their physiologhy. Their alpha granules and dense bodies secrete a large number of agents that are involved in haemostasis, and the glycoproteins on their surfaces form the linkages with proteins like fibrinogen, fibronectin, collagen and von Willebrand factor that are necessary for adhesion and aggregation (Frojmovic, 1998). Diseases such as heart attack (Meade, 1992), stroke (Harker, 1998) and eclampsia (Schindler et al., 1990), can be the result of pathologies in platelets. Although devices have been recently developed to diagnose platelet function (Nicholson et al., 1998), there is still a need for devices that can examine the multiple factors of platelet physiology that affect thrombus formation. Because fluid shear is a key factor in platelet adhesion and aggregation (Colantuoni et al., 1977), it is necessary to test platelet function under conditions of flow. Also, because of the large number of adhesion receptors and secreted agents that make up a platelet’s physiology, a complete diagnosis of platelet function should be performed on a variety of substrates.