bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development and Testing of a Telemanipulation System With Arm and Hand Motion
Authors: Turner Michael L. , Findley Ryan P. , Griffin Weston B. , Cutkosky Mark R. , Gomez Daniel H. 
Published: November 2021

Abstract
This paper describes the development of a system for dexterous telemanipulation and presents the results of tests involving simple manipulation tasks. The user wears an instrumented glove augmented with an arm-grounded haptic feedback apparatus. A linkage attached to the user’s wrist measures gross motions of the arm. The movements of the user are transferred to a two fingered dexterous robot hand mounted on the end of a 4-DOF industrial robot arm. Forces measured at the robot fingers can be transmitted back to the user via the haptic feedback apparatus. The results obtained in block-stacking and object-rolling experiments indicate that the addition of force feedback to the user did not improve the speed of task execution. In fact, in some cases the presence of incomplete force information is detrimental to performance speed compared to no force information. There are indications that the presence of force feedback did aid in task learning.
Haptic Interaction Within a Planar Environment
Authors: DiMaio S. P. , Salcudean S. E. , Sirouspour M. R. 
Published: November 2021

Abstract
A haptic simulation environment to simulate planar three-degree-of-freedom motion has been developed by the authors. The system consists of a novel parallel manipulandum and associated control, collision detection and dynamic simulation software running on a QNX PC. This paper describes haptic interface control and outlines the control systems that have been designed for the haptic rendering of virtual environments. Virtual environment design and implementation are also discussed. Using the haptic simulation environment that has been developed, a four-channel teleoperation architecture is shown to be an effective means to display a variety of simulated environments and is compared with a popular impedance-based approach.
Modeling Vehicles’ Offset Impacts Using Recurrent Artificial Neural Networks
Authors: Omar Tarek A. , Eskandarian Azim , Bedewi Nabih E. 
Published: November 2021

Abstract
In the last few years, the demand for general-purpose Finite Element (FE) vehicle models with fine mesh and small elements has increased the size of these models dramatically. The FE simulation of these models requires extensive CPU time, which makes the simulation cost an important issue to consider. The main objective of this research is to develop an accurate and computationally inexpensive method to predict a vehicle’s crash performance in the event of a collision. This becomes very important as the demand for performing several impact scenarios for each vehicle becomes excessive. This demand is driven by the desire to investigate different impact scenarios and to study the effect of the impact velocity, the offset-barrier ratio, and the impact angle on the dynamic behavior of the vehicle structure in crash events.
In the last decade, Artificial Neural Networks (ANN) emerged as a reliable tool for solving nonlinear problems in variety of applications. The most important feature in ANNs is its ability to infer the nonlinear characteristics of any complex system, even if the mathematical model of the system does not exist. This is an extremely important feature when dealing with highly nonlinear dynamic problems such as vehicles collision. In a previous research conducted by the authors, advanced ANNs were developed and trained to model vehicles frontal impacts. This paper extends the concept and technique in order to use ANNs in modeling vehicles offset-barrier impacts.
Special ANNs were developed, trained and tested through numerical examples for two different offset impact cases. The first case was 50% offset-barrier impact at five different impact velocities, while the second case was 35 mph frontal impact at five different offset-barrier ratios. Validated FE vehicle model was used to perform FE simulations for many different offset-barrier impacts. The crash profiles obtained from the FE simulations were used to train and test the developed ANNs. The results of these numerical examples indicated the ability of the ANNs to accurately capture the nonlinear dynamic characteristics of the vehicle structure for offset impacts. The trained networks could then be used to predict the crash profiles of any offset impact scenario within the training range.
A Systems Modeling Methodology for Estimation of Harm in the Automotive Accident Environment
Authors: Kuchar Alexandra C. , Greif Robert , Neat George W. 
Published: November 2021

Abstract
A systems modeling approach is presented for assessment of harm in the automotive accident environment. The methodology consists of parametric simulation of several controlled accident variables, with case results weighted by the relative frequency of each specific event. A hierarchy of models is proposed, consisting of a statistical model to define the accident environment and assign weighting factors for each crash situation case, and vehicle and occupant models for kinematic simulation of crash events. Head and chest injury results obtained from simulation are converted to harm vectors, in terms of probabilistic Abbreviated Injury Scale (AIS) distributions based on previously defined risk analyses. These harm vectors are weighted by each case’s probability as defined by the statistical model, and summed to obtain a total estimate of harm for the accident environment. The methodology is applied to a subset accident environment consisting of single- and two-vehicle frontal collisions among passenger cars and light trucks. The model is validated against injury field data, and is found to accurately reflect trends in distribution of injury severity while slightly underestimating moderate to severe injuries. The model is also exercised for variable sensitivity analyses, wherein the effects of light truck/car population mix are evaluated in terms of their impact on occupant harm within the subset accident environment.
Injury Assessment of the Portable Vehicle Arresting Barrier (PVAB)
Authors: Bir Cynthia , Atkinson Theresa 
Published: November 2021

Abstract
The Portable Vehicle Arresting Barrier (PVAB) was developed in an effort to promote area denial, enforce roadblocks, and improve security to a local area. A netting system is used to trap and stop a vehicle within 200 feet of the capture point. A kinetic effect assessment was conducted to determine whether occupant protection was affected by the capture event. The crashworthiness assessment of the PVAB was completed in two phases: a review of a “real world” crash database (NASS) and experimental testing with biomechanical surrogates (Hybrid III). The database review and the experimental testing show that capture with the PVAB system results in primarily minor injuries.
Raw Materials and Processing Issues in the Development of Vascugel, a Cell Therapy for Vascular Disease
Authors: Sigler James S. 
Published: November 2021

Abstract
Vascular arterial disease is the most common cause of death in the United States. Cardiovascular surgery such as coronary artery bypass graft surgery and therapies such as angioplasty and stenting are the current standard of care. However, a large number of these procedures fail due to a form of arterial disease known as restenosis. Restenosis is the re-narrowing of the treated blood vessel following vessel wall injury resulting in decreased blood flow. This re-narrowing occurs in large part because the smooth muscle cells in the wall of the vessel proliferate after the vessel is damaged. This proliferation occurs because the endothelial cells lining the inside of the vessel, which normally control proliferation, are damaged and can no longer provide the physiological function of keeping the underlying smooth muscle cells in a steady state. Of the approximately 1.5 million procedures per year, over 500,000 are coronary artery bypass graft surgeries (1996 and 1998 data from Medical Data International). Coronary artery bypass grafts experience restenosis at a 12 to 20% rate after one year.
Spinal Cord Stress and Strain Predictions in a Ligamentous C5-C6 Segment
Authors: Scifert J. , Totoribe K. , Goel V. , Clark C. , Reinhardt J. , Bolinger L. 
Published: November 2021

Abstract
Several spinal disorders and traumatic loading situations are known to inflict damage to neurovascular components of the cervical spinal cord. Studies have shown that damage to the spinal cord can occur regardless of significant damage to surrounding structures. To understand the mechanics of spinal cord injury, one needs to quantify stresses and strains within the spinal cord and its components in response to exterrnal loads applied to the bony spine. Experimental studies can not address this issue. This study presents a Finite Element (FE) model to quantify the physiologic strains and stresses in the cervical spinal cord placed in the ligamentous C5-C6 motion segment, with loads applied to the bony segment and not the the cord itself, as have been done in experimental studies reported in the literature.
Magnetic Resonance Images of Tendon Microstructure
Authors: Israel Rajakumar , Atkinson Theresa 
Published: November 2021

Abstract
Tendon and ligament typically produce a weak signal during Magnetic Resonance Imaging (MRI). As a result only gross defects in the tissue could be detected. A method was recently developed to allow more detailed images of tendon structure to be obtained. This new method requires less than 2.5 minutes per scan and is therefore a reasonable method to utilize in a clinical setting to evaluate tendon or ligament injury and healing.
Impact of Thresholding Techniques on Micro-CT Image Based Computational Models of Trabecular Bone
Authors: Eichler Mark J. , Kim Chi Hyun , Müller Ralph , Guo X. Edward 
Published: November 2021

Abstract
Age-related bone fractures are mostly influenced by trabecular bone sites. Trabecular bone constantly adapts its bone volume fraction (BV/TV) and orientation, and thus its mechanical properties, to mechanical usage. Therefore, understanding the trabecular bone adaptation process and its consequences will contribute to the better understanding of the etiology of age-related fractures. Micro-computed tomography (micro-CT) is a relatively new method to quantify the complex three-dimensional (3D) trabecular bone architecture [1,2]. Finite element computational studies can be performed on these 3D microstructural images by converting each image voxel into an element [3,4,5]. Image thresholding techniques to segment bone voxels from bone marrow voxels have a major impact on the results of these models. However, the influence of different types of thresholding techniques on the mechanical properties of bone has not been examined carefully.
Interaction of Airflow With Viscoelastic Gel in Endotracheal Tubes
Authors: Hassan Amgad A. , Evrensel Cahit A. , Krumpe Peter E. 
Published: November 2021

Abstract
The clearance of mucus from endotracheal (ET) tubes by a simulated cough is studied experimentally. Cough is approximated as a pulse of 0.3-second duration. A viscoelastic gel, Locust Bean Gum (LBG)/Borax solution, is used as mucus simulant. The relationships between mucus rheology, tube diameter, clearance are examined. Tube diameters ranging from 6mm to 10mm are used in this study. The displacement of the mass center of the simulant drop (0.1 ml) is measured. Our investigation shows that, for the same average air speed in the ET tube, the displacement is increased with the decreasing diameter. The results also indicate that, although simulant with lower viscosity/elasticity ratio requires lower air velocity for initial movement of the simulant surface, its mass center moves a shorter distance compared to a simulant with higher viscosity/elasticity ratio if the air velocity is increased further.
Imaging and Measurement of the Separation Surface Between Converging Fluids of Differing Viscosity at a Microscopic Branch
Authors: Peach J. P. , Hitt D. L. 
Published: November 2021

Abstract
The mechanics of branching blood flow is of fundamental importance in understanding the nonuniform distribution of blood components within a microvascular network and, indeed, even within an individual vessel. The nonuniformity resulting from the branch can in turn impact microvascular flow impedance and oxygen transport processes. A construct known as the “separation surface” is often used to describe the flow at converging (venular) and diverging (arteriolar) branches. In the case of two converging flows, the separation surface identifies the portions of the flow in the outlet branch which originated from each of the two feeding branches. The reverse situation holds for a diverging branch. If the converging fluids are immiscible, then the separation surface is a persistent, physical surface within the flow. For converging blood flow, mixing occurs and the separation surface loses its definition with downstream position.
Parametric Meshing of Finite Element Models of Lumbar Spine
Authors: Kasra Mehran 
Published: November 2021

Abstract
In a finite element model, material properties, loading condition, and constraint condition can be changed easily as variable parameters. However, changing a finite element mesh representing different geometries may be a very difficult task, especially for a large and complicated model such as that of lumbar spine. In this case, changing the model geometry can be done easily, if it can be defined with mathematical functions and a set of geometrical parameters.
Manufacturing of Functionally Graded Materials
Authors: Kahlen Franz-Josef , Kar Aravinda 
Published: November 2021

Abstract
Laser deposition of metal layers has been recognized in recent years as a one-step process to fabricate metal parts. A one-dimensional model was developed to calculate the plume temperature, process parameters and melt pool characteristics. The model accounts for the transmission of the laser beam through the plume, energy transfer in the molten phase and the Stefan conditions at the solid-liquid and liquid-vapor interfaces. The surface temperature at the molten surface is found to exceed the normal boiling temperature causing the pressure to be higher than one atmospheric pressure. The plume temperatures were found to be below the respective material’s ionization temperature. The calculated plume temperatures are in good agreement with the values obtained from the spectral data. Also, the model predictions for remelt layer depth, deposition height and plasma height compare well with experimental data. The authors have employed this one-step technique to create graded materials by varying the part’s composition from 100% stainless steel to a 100% nickel-based superalloy. Mechanical properties of these graded materials are measured and the effects of slow solidification rates are investigated.
Probabilistic Optimum Design of Aircraft Structures
Authors: Onyebueke Landon , Nnamani Ikechukwu 
Published: November 2021

Abstract
This paper discusses the application of probabilistic design methodology for the optimum design of aircraft structures. Material properties and loads are considered as stochastic data in formulating the optimization model for the design. The procedure accommodates various types of sensitivity analyses. Attention is focused on studies in which both the aerodynamic and structural designs are optimized simultaneously. Tradeoffs between drag and structural weight for aircraft wings are affected by two aerodynamic-structural interactions. First, structural weight affects the required lift and, thus drag. Second, structural deformations change the aerodynamic shape.
Design results obtained using the Monte Carlo simulation method, and the limit state function approach, are presented. The limit state function method applies the Most Probable Point (MPP) search approach. Some of the approximate methods that have been applied for the search are FORM, AMV, AIS, etc.
Development and Validation of the Small Punch Test for UHMWPE Used in Total Joint Replacements
Authors: Edidin A. A. , Kurtz S. M. 
Published: November 2021

Abstract
Around 500,000 total hip and knee arthroplasties are performed each year in the United States, with a comparable number performed annually throughout the rest of the world. Since its development in the 1960s, contemporary total joint arthroplasty has proven to be extremely successful in alleviating pain and restoring joint function. However, for a minority of patients, mechanical and biological sequelae emanating from the breakdown of the ultra-high molecular weight polyethylene (UHMPWE) bearings limit the longevity of the procedures.
A Probabilistic Approach to the Modeling of Coarse Grain Heat Affected Zone Fracture in A707 Steel Welds
Authors: Zhou J. , Soboyejo W. O. 
Published: November 2021

Abstract
A probabilistic framework is presented for the modeling of the variability in crack-tip opening displacement (fracture toughness) during the fracture of coarse grained heat affected zones in A707 steel welds. The variability in inclusion distribution and fracture conditions is modeled using weak link statistics in physically-based fracture mechanics models that describe the fracture behavior in the lower-shelf and transition-temperature regimes. The models are used to explain the measured trends in experiments designed to explore the effects of heat input on crack-tip opening displacement. The implications of the results are also analyzed for the design of welded structures.
Laser Shock Peening for Fatigue Resistance
Authors: Clauer Allan H. , Lahrman David F. 
Published: November 2021

Abstract
Laser shock peening is developing into a commercial surface enhancement process for increasing the fatigue life of metal components. The process produces deep residual compressive stresses into treated surfaces which inhibit the initiation and propagation of fatigue cracks. The process has been particularly effective in increasing the resistance to foreign object damage in fan and compressor blades of aircraft gas turbine engines. However, the potential application of this process is much broader, encompassing automotive, tooling and dies, and others. Significant effort is being made to lower the cost and increase the throughput of the process, to make it an affordable process for many more applications. This describes the process and reviews the progress being made in the technology, both in material property enhancement and use of the process, and towards reducing cost and increasing throughput.
Mechanisms Controlling the Performance and Durability of Thermal Barrier Coatings
Authors: Mumm Daniel R. , Evans Anthony G. 
Published: November 2021

Abstract
Thermal protection systems based on ceramic thermal barrier coatings (TBCs) are used extensively to protect hot-section components in gas turbine engines. They comprise thermally insulating ceramic coatings, deposited on an aluminum-containing intermetallic bond coat (BC) that provides oxidation protection. A thin thermally-grown oxide (TGO layer forms between the TBC and BC during cyclic thermal exposure. Each of the system constituents evolves in service and all interact during thermal cycling to control the thermo-mechanical performance of the system. Exposed to thermal cycling conditions, TBC systems are susceptible to loss of adhesion and spalling failures. Multiple failure mechanisms exist, dependent upon differing thermal histoiy and processing approach for various coating systems. Coating failure is ultimately controlled by the large residual compression in the TGO and its role in amplifying the effects of imperfections in the vicinity of the TGO. The failure occurs through a process involving crack nucleation, propagation and coalescence events. For a particular commercial system, it is found that the TGO ‘ratchets’ into the bond coat with each thermal cycle, at an array of interfacial sites. The displacements induce strains in the superposed TBC that cause it to crack. The cracks extend laterally as the TGO ratcheting process proceeds, until the cracks from neighboring sites coalesce. Once this happens, the system fails by large scale buckling. It is shown that the displacements are ‘vectored’ by a lateral component of the growth strain in the TGO. The relative roles of bond coat visco-plasticity, initial interface morphology, and phase evolution are discuss. The behavior observed for this system is compared with predictions of a ratcheting model, as well as with the behavior observed for other commercial coating systems.
Growth and Failure of Oxide Irregularities During Thermal Cycling: Interactions Between Stress, Geometry and Oxide Formation
Authors: Begley M. R. , Ambrico J. M. , Jordan E. H. 
Published: November 2021

Abstract
In some oxide thin film systems, such thermal barrier coating systems (TBCs), thermal cycling leads to the development of geometric irregularities in the film. The evolution of these irregularities involves very large changes in aspect-ratio and often occurs rapidly over several hundreds of cycles. A key aspect of this behavior is the development of tensile stresses in the irregularity due to plastic yielding of the surrounding metal. These stresses can accelerate the elongation of the oxide (which translates into shape evolution of the irregularity) by various mechanisms, including enhanced oxide formation, inelastic stretching (creep) and failure of the oxide. An idealized analytical model consisting of a thin elastic shell embedded in an elastic-plastic matrix is used to explore the interactions between geometry, thermal strains, plasticity and oxide growth. Boundaries between purely elastic deformation, uni-directional yielding and reversed plasticity are shown to have a strong dependence on the size of the irregularity relative to the oxide thickness. For any given thermal strain, there is a critical aspect ratio of the irregularity that leads to maximum tensile stress in the oxide. The resulting closed-form solutions allow for quick and easy evaluations of various oxide-growth scenarios, including stress-dependent oxide formation. This talk will present the application of these models to TBC thermal cycling experiments, and discuss how stress-dependent oxide formation plays a role in the rapid evolution of these irregularities. A variety of oxide growth scenarios will be illustrated, and used to demonstrate that oxide failure and subsequent oxide formation in the cracked region is the most likely explanation for the rapid shape evolution seen in the experiments.