bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and Development of Magneto Rheological Dampers for Bicycle Suspensions
Authors: Ahmadian Mehdi
Published: December 2021

The design and fabrication of a magneto rheological (MR) damper for bicycle suspension applications is addressed. Two 1998 Judy® Dampers are retrofitted with MR valves, to achieve the damping force adjustability that the MR fluid offers. One design attempts to use as many of the Judy® Damper components as possible. The second design significantly modifies the Judy® Damper, to better accommodate the MR valve and ease of fabrication and assembly, although fitting into the same envelope as the Judy® damper for a direct retrofit. The two MR dampers are fabricated and assembled for force-velocity characterization testing. The test results show that properly-designed MR dampers can provide significant dynamic performance improvements, as compared to conventional passive bicycle dampers.
Lumped-Parameter Modelling of Spatial Compliance Using a Twist-Based Potential Function
Authors: Fasse Ernest D. , Zhang Shilong
Published: December 2021

This paper examines geometric modelling of elastically coupled, spatial rigid body pairs. For a pair of elastically coupled rigid bodies there exist coincident, unique points on the bodies or their rigid extensions known as centers of stiffness at which translation and rotation are minimally coupled. The rigid body displacement of frames at the centers of stiffness can be associated with a twist displacement, a continuous rigid body motion. A potential function is defined that is a simple quadratic function of the twist displacement. Constitutive equations relating rigid body displacement and wrench are derived. While the problem of modelling and computer simulation is emphasized, the work is also relevant for active compliance control of robotic devices.
Adaptive Fuzzy Control of Tension Variations due to the Eccentric Unwinding Roll in Multi-Span Web Transport Systems
Authors: Jee Sungchul , Kim Sungchol , Shin Kee-Hyun
Published: December 2021

Disturbances due to the eccentric unwinding roll/roller can create significant tension variations in the web spans in multi-driven web transport systems. The drivers are interconnected by an elastic web material (a 14-micrometer thick Polypropylene film was used for this study). Specifically, eccentricity of an upstream roller such as an unwinding roll creates upstream tension variation, and the tension variation in upstream web spans is transported to downstream due to the interconnection between the web spans. However, it is not easy to obtain an accurate mathematical model of the web transport system, for the design of a tension controller, which contains several actuators, sensors, gears, bearing systems, and interconnected web spans.

In this paper, an adaptive fuzzy controller which automatically tunes its parameters in real-time is suggested to regulate tension variations in multi-spans due to an eccentric unwinding roll. In the proposed method, the input and output ranges are adjusted together according to continuous observation of tension error and change in the error. The proposed controller is implemented on a prototype web transport system which consists of three AC motors, real-time target controllers, unwinding and winding rolls with two-spans of web including sensors for the measurement of tensions and speeds of the web.

The Experimental results show that the proposed adaptive fuzzy controller successfully rejects the effects of the disturbances due to the eccentric unwinding roll and substantially reduces the tension variations in both web spans. The adaptive fuzzy controller outperformed the conventional PID controller as the frequency of the eccentricity disturbance increased.
Design of a Frangible Laminated Composite Launch Tube Closure
Authors: Wang W. T. , Wu J. H. , Kam T. Y.
Published: December 2021

The concepts of designing a laminated composite frangible launch tube closure are elaborated. The frangible closure is a convex shell structure of which the external failure pressure is much higher than the internal failure pressure. The frangible closure is designed in such a way that when subjected to an internal impulsive pressure of magnitude greater than certain value, the closure will be broken into several pieces in accordance with a predetermined failure pattern. A number of frangible closures of different sizes are fabricated and subjected to burst strength tests. The failure modes and the effects of some specific design variables on the burst strength of the closure are studied using the experimental results. Basically, the frangible closure can achieve the design objectives.
Composite Materials Use: A Particular Case of Safety-Related Service Water Pipes
Authors: Le Courtois Th. , Pays M. F.
Published: December 2021

This paper shows the present and future uses of composite materials in French nuclear and fossil-fuel power plants. It sets the EDF composite materials market in the general composite materials market and shows the great interest that EDF takes in these materials which are corrosion resistant in most fluid handling applications.

Electricité de France has decided to install composite materials in service water piping in its nuclear power plant (PWR) at Civaux (West of France) and for the first time in France, in safety-related applications. Our requirements are thus much more severe than is usually the case and the choices (for the basic materials, the manufacturing, the design rules, and the non destructive testing methods) have to be justified before our Safety Authorities.

A wide range of studies has been performed about the durability, the control and damage mechanisms of those materials under service conditions among an ongoing Research and Development project. The main results are presented under the following headlines:

• Selection of basic materials and manufacturing processes,

• Aging processes (mechanical behavior during « lifetime »),

• Design rules,

• Non destructive examination during manufacturing process and during operation.

The studies have been focused on epoxy glass pipings: the actual application is the circuits for the nuclear power plant in Civaux, the supplies and installation of the pipes have largely begun.

We underline the importance of strong quality insurance policy requirements towards production and installation companies. We present a study of the use of composite pipes in power plants (hydraulic, fossil fuel, and nuclear) in France whether it be safety related or non safety-related applications. We present the different technical solutions for materials and manufacturing processes and an economic comparison between steel and composite pipes. Finally, we give the general conclusions of the R&D program.
Magnetic Calibration by Tetrahedral Interpolation
Authors: Briggs William
Published: December 2021

This paper presents a method for discovering a work area’s magnetic characteristics using relatively sparse data from a magnetic tracker. It then explains a method based on creating tetrahedrons to create a lookup table used in compensating for the positional data component quickly during runtime. The paper also describes initial “before” and “after” results for a noisy lab, including visuals and statistical data. Finally new techniques are discussed for further refinement and future development.
Digital Humans in Virtual Environments
Authors: Yee Andrew , Nebel Kyle J.
Published: December 2021

This paper discusses the cooperative research and development work between Delphi Interior Systems (formerly known as Delphi interior & Lighting Systems) and the U.S. Army’s Tank Automotive & Armaments Command, Research, Development, and Engineering Center (TARDEC). Technical Areas addressed include real time human interaction, scripted simulations, alternative approaches to scripting, digital human factor analysis, and how ergonomic software interfaces with virtual manufacturing/simulation environments.
Virtual Manufacturing Tools in the Product Design Environment
Authors: Braun Ronald C. , Marx Warren G.
Published: December 2021

Design and manufacturing modeling and simulation have been identified as important to the principles of lean product development. Early in the product development cycle, the use of three-dimensional (3-D) engineering models allows us to electronically (or virtually) prototype physical products, and conduct product feasibility and producibility studies. Manufacturing issues can be identified early and used to drive the product design toward the lowest cost. This paper describes the Northrop Grumman Corporation (NGC) approach to extending classic prototype simulation to virtual manufacturing (VM) tools that accommodate the visualization of interacting production processes, process planning, scheduling, and assembly planning. Previous simulation tools were limited to the design environment. Our tools not only support design; they also provide functionality by bringing the results to the assembly floor. The use of these tools has resulted in “first-time quality” both above and on the shop floor, with significant reductions in product cost and cycle time.
A Virtual Reality Enabling Parameterization of CFD Simulations for Non-Empty Room Layout Design
Authors: Giallorenzo Vito , Banerjee Pat
Published: December 2021

In this paper, a new approach of establishing the Computational Fluid Dynamics (CFD) - Virtual Reality (VR) design interface is described. Near optimal configuration of all the parameters affecting the contaminant removal is the most important factor that determines the effectiveness of the cleanliness of the indoor air. The main limitation encountered in applying VR to CFD aided design is due to complex and time consuming setup and computation steps of a CFD analysis. Consequently a CFD computation of the airflow pattern is done separately with a traditional CFD solver and then the data is imported in VR. This makes it infeasible to use CFD/VR to analyze a large number of layout design alternatives.

A novel method for overcoming this problem has been conceptualized by using a VR preprocessing step. A mathematical expression of the dependence of the contaminant removal effectiveness on room parameters has been developed based on the experimental result. In this way, the selected set of preferred solutions is selected among the enormous number of possible alternatives. The restricted set of room layouts is further investigated by VR analysis of the CFD simulation. This provides insight for an effective positioning of all parameters for room air cleanliness. This two step CFD/VR aided design technique allows overcoming the problems that affect the integration of CFD and VR technique in design of contaminant-free environments.

The methodology is well suited for the design of special indoor environments such as tuberculosis hospital facilities, clean rooms and certain electronic, pharmaceutical and chemical manufacturing facility rooms with special contamination control requirements.
Elastic Response of a Submerged Plate Coated With Multiple Layers of Elastomeric Materials in the Presence of a Turbulent Boundary Layer
Authors: Mendoza Jeff M. , Pham Hoang
Published: December 2021

This study addresses the elastic response of a submerged plate coated with multiple layers of elastomeric materials. of interest is the extent at which the mechanism of interaction between dissimilar elastomers can be modified through selection of material properties. Such modification can optimize the received signal response at the sensors in the presence of a turbulent boundary layer (TBL) as well as provide insight into advantageous TBL and structure-borne vibration decoupling configurations. The analytical model is an infinite multilayer composite of steel and viscoelastic materials separating the semi-infinite media of water (external) and air (internal). The theory of elasticity expedites the analysis of elastic response, governed by dilatational and shear motion, in each layer. The analysis considers excitation by an incident plane wave in addition to a fully developed TBL both in the water medium. A series of numerical simulations based on material properties of well-characterized elastomers quantify the degree at which this coupling mechanism can be optimized in applications of noise and vibration reduction.
How to Measure the Internal Forces of a Combustion Engine
Authors: Takahashi Yukitaka , Kamimura Naoki , Suzuki Toshibumi , Urakabe Kouji , Suzuki Hideo , Wada Shinji
Published: December 2021

It has become increasingly important to reduce the powertrain vibration which mainly affects the interior noise of vehicle during acceleration. In the past a number of studies were made based on indirect methods including a calculation using measured values of vibration and an identification by means of an FRF. This paper reports on a new direct method for defining the load direction and values obtain from strain gauges attached to each main bearing journal of the powertrain.
A Hybrid Finite Element Method for Calculating the Vibration of Co-Linear Beams in the Mid-Frequency Range
Authors: Zhao Xi , Vlahopoulos Nickolas
Published: December 2021

The theoretical development of a hybrid finite element method is presented. It combines conventional Finite Element Analysis (FEA) with Energy Finite Element Analysis (EFEA) in order to achieve a numerical solution to mid-frequency vibrations. In the mid-frequency range a system is comprised by some members that contain several wavelengths and some members that contain a small number of wavelengths. The former are considered long members and they are modeled by the EFEA. The latter are considered short and they are modeled by the FEA. The new formulation is based on deriving appropriate interface conditions at the joints between sections modeled by the EFEA and the FEA methods. Since the work presented in this paper constitutes a fundamental step in the development of a hybrid method for mid-frequency analysis, the formulation for one flexural degree of freedom in co-linear beams is presented. The excitation is considered to be applied on a long member and the response of the entire system is computed. Uncertainty effects are imposed only on the long members of the system. Validation cases for several configurations are presented.
Basic Analytical Modeling of the Piston Slap in Conjunction With Engine Block Vibration
Authors: Siavoshani Saeed J. , Latcha Michael A.
Published: December 2021

The objective of this research is to enhance and develop analytical and experimental schemes to study the source and path analysis of piston slap noise and to develop tools to relate the piston slap to the engine block vibration. These computer tools solve the piston dynamics and the engine block vibration. The results of this approach are block vibrations that are comparable to experimental results. This study resulted in an analytical approach to understand the piston dynamics in conjunction with block vibration. The engine block vibration was obtained using both a coupled and uncoupled approach due to the piston slap. The coupled approach was to solve the piston motion along with the flexible motion of the cylinder bore which yields the cylinder block vibration directly. The uncoupled approach consists of solving for the contact forces with the simple cylinder model; then using those forces in an FEA analysis of the engine block to determine the resulting vibration.
Shape Optimization of Isotropic Composite Beams Undergoing Harmonic Flexural and Torsional Loading
Authors: Lumsdaine Arnold , Garcia Arnoldo , Yao Ying
Published: December 2021

The purpose of this study is to optimize beams undergoing harmonic excitation in both bending and torsion due to an intermediate mass and inertial component. The objective is to minimize the weight for a composite beam made of glass reinforced acrylonitrile butadiene styrene (ABS), while maintaining performance above a given natural frequency. Design variables are the cross-sectional dimensions. Weight reduction is computed compared to a uniform case. The results are obtained for two different composites with different glass densities, and compared with results obtained with a steel structure.

The structure examined is a clamped-clamped beam with an intermediate mass and inertial component. Basic structures are modeled and optimized analytically. Coupling effects are modeled discretely using finite elements, and these structures are optimized using commercial software. Structures with closed (circular) and open (channel) cross-sections are examined. Results show order of magnitude improvement of optimized structures for both steel and composite beams.
Effects of Low Frequency Induced Excitations on Fluttering Panels in Supersonic Flow
Authors: Surace Giuseppe , Udrescu Radu
Published: December 2021

The paper extends the classical problem of nonlinear panel flutter to the analysis of the effects of external forcing on aerodynamically self-excited thin plates structures of high speed vehicles. This phenomenon can be induced by the aeroeacoustic excitation of noise, boundary layer, or oscillating shock waves. The problem is formulated within nonlinear elastic and linear aerodynamic theories by using a complex finite element model consisting of fifth order plate and second order membrane triangular elements. The excitation is applied harmonically as uniformly distributed pressures. In most cases the pattern of the dynamic response includes a transient period in which the fluttering motion is disturbed into a forced vibration (the steady-state motion) having the same frequency as the excitation. There are also conditions for complex motions having larger amplitudes (than those of the free auto-oscillating system) of both frequencies of flutter and excitation, respectively.
Longitudinal and Out-of-Plane Stiffness of a Web in an Air-Flotation Oven
Authors: Chang Young B. , Swanson Ronald P. , Moretti Peter M.
Published: December 2021

Air-flotation ovens are used for non-contact drying of coated web materials such as photographic film, magnetic media, and paper. In a typical air-flotation oven, the air bars are arranged in such a way that the path of web is nearly sinusoidal. When web tension fluctuates, the distance between the web and the air bars also changes. This phenomenon affects the longitudinal dynamics and tension control of an air-floated web. In some cases, tension fluctuations can cause the web to touch the air bars, resulting in damage to the coating and the web. This paper discusses an analytical model of the extensional resiliency of an air-floated web. The analysis shows that at low tension the longitudinal stiffness of an air-floated web is small, being dominated by the air cushion effects. At higher web tension, however, the effects of material deformation become more important than the air cushion effects. The analysis is compared with the experimental results obtained in a pilot air-flotation oven. The analytical and experimental results show the same trends, though the analytical model tends to underpredict the longitudinal stiffness of air-supported webs.
High-Aspect-Ratio Electroplated Structures With 2μm Beamwidth
Authors: Li Xiaobin , Kiyawat Siddharth , De Los Santos Hector J. , Kim Chang-Jin “CJ”
Published: December 2021

Narrow beamwidth is highly desirable for many micromechanical elements moving parallel to the substrate. A good example is the electrostatically driven flexure structure, whose driving voltage is determined by the width of the beam. This paper presents the process flow and the result of a high-aspect-ratio electroplating process using photoresist (PR) molds. Following a systematic optimization method, PR molds with aspect ratios up to 4.0 were fabricated with a beamwidth of only 2.1μm. Higher aspect ratios, up to 6.8, were achieved using PR double coating technique, with a beamwidth of 2.6μm. Using a Cr/Cu seed layer, nickel electroplating was successfully carried out to translate the PR molds into nickel micro-structures. We observed bend-down of the fully released nickel cantilevers that are over 8μm thick. Further investigation suggested a combined effect of residual stress gradient in the electroplated nickel layer and in-use stiction of the cantilever beams.
EFAB: High Aspect Ratio, Arbitrary 3-D Metal Microstructures Using a Low-Cost Automated Batch Process
Authors: Tseng Fan-Gang , Zhang Gang , Frodis Uri , Cohen Adam , Mansfeld Florian , Will Peter
Published: December 2021

EFAB (“Electrochemical FABrication”) is a new micromachining process utilizing an innovative “Instant Masking” (IM) technique to electrochemically deposit an unlimited number of metal layers for microfabrication. Through this approach, high-aspect-ratio microstructures with arbitrary 3-D geometry can be rapidly and automatically batch-fabricated at low temperature (< 60 °C) using an inexpensive desktop machine. IC-MEMS integration can also be carried out by this low temperature process.
Fabrication of High-Index Refractive Microlenses for Near-Field Optics
Authors: Fletcher D. A. , Crozier K. B. , Kino G. S. , Quate C. F. , Goodson K. E.
Published: December 2021

The minimum spatial resolution of optical systems in the diffraction limit is approximately the free space wavelength divided by twice the numerical aperture (NA) of the system. NA is defined as the product of the index of refraction at the focal point and the sine of the maximum convergence angle of the light. Resolution below the diffraction limit in air can be achieved with a solid immersion lens (SIL) by scanning a sample within the near field of a spot formed in a high refractive-index lens material in the manner of Mansfield and Kino (1990). This paper presents a technique for microfabricating high-NA SILs in silicon with diameters on the order of 10 μm. Silicon has a higher index than previously demonstrated SILs, and it transmits well in the mid-infrared and near-infrared wavelength ranges, making it an ideal choice for high-resolution thermometry and spectroscopy. However, traditional methods for manufacturing SILs are time consuming, labor intensive, and expensive and cannot typically be used to make lenses smaller than 1 mm in diameter. We review current microlens fabrication techniques and describe the fabrication process developed for this work. We include a method for lens formation using acetone vapor to reflow photoresist pillars that can be used to make aspherical as well as spherical lenses. Microlenses etched in single-crystal silicon with diameters on the order of 10 μm and NAs as high as 3.0 are shown. Wafer-scale fabrication offers the opportunity to integrate microlenses onto MEMs structures such as scanning probes for optical imaging, lithography, spectroscopy, and thermometry with high optical efficiency and spatial resolution.
Laser Opto Microactuators Rotated by Molecular Gas Dynamics Effects
Authors: Ota Masahiro , Watanabe Yu-ichi , Sakamoto Moriyoshi
Published: December 2021

In this paper, a selective optical absorber plate and an anodic oxidation alumina are proposed for the rotor of an opto microactuator used as an actuator in a micromachine. The thin films of the selective optical absorber plate are fabricated by vacuum deposition. The substrates used are pyrex glass at the first stage and aluminum at the second stage. Deposition on the pyrex glass substrates is carried out in order to estimate the deposition rate and determine the characteristics of the deposited films. Germanium and silicon oxide are selected as the materials for the selective optical absorber thin films. Germanium is used as to absorb the visible beam from a laser generator. In contrast, silicon oxide is used because it has a small reflectance for visible light. The selective optical absorber-plates for the rotors of the opto microactuator consist of aluminum substrates on which germanium thin films and silicon oxide thin films are deposited. A germanium film is deposited on an aluminum substrate first and then a silicon film is deposited on the germanium film. Therefore, the rotor surface has a small reflectance for visible light and a large reflectance for infrared light. The surface with the deposited films is called the front surface and the opposite surface is called a rear surface. The rear surface is an aluminum plate with the anodic oxidation alumina film for low heat conductivity, large emissivity and thermal insulation. The insulated rotors can keep the temperature difference by greater than 10 Kelvin, even if the irradiation times are longer than 200 seconds. There are 3 reasons why the insulating rotor can keep the temperature difference. They are occurrence of a contact resistance, an increase of a surface area and a small heat conductivity of anodic oxidation alumina.
Suspension Handling System
Authors: Baechi Daniel , Buser Rudolf
Published: December 2021

A new idea of a particle handling system is proposed in this paper consisting of a network of channels and a matrix of mechanical gates for fluids. The device consists of a silicon chip encapsulated by two glass chips. A free standing silicone membrane with a thickness of only two microns is used to reduce the cross sections of the channels. The selected cross section of 30 × 7 μm allows to handle particles with sizes ranging from the sub micron scale to a few microns. We could show that the flow of these particles in the channels can be controlled by actuating the valves and monitored with a video microscope. The density of valves is 600 valves / square inch in our first prototype. The second prototype with a valve density of 100 valves / square inch also includes channels for cooling of the device.
Design of a Chip Based Microanalytical Fluidic System Based on Electrochemical Detection Using Redox Cycling
Authors: Richard Åse , Klett Oliver , Strandman Carola , Bäcklund Ylva , Nyholm Leif
Published: December 2021

Microelectrodes on a chip have been investigated regarding their usefulness for dual electrode amperometric detection in off-chip and on-chip based microanalytical capillary flow systems. In the latter case, microelectrodes were integrated on a chip containing fluidic channels. A straightforward method to micromechanically manufacture the chips is presented. In this process, the microelectrodes are manufactured on a Pyrex (Corning #7740) glass wafer and anodically bonded to an oxidized silicon wafer into which fluidic channels of varying width and depth have been manufactured.
Micromechanical Devices With Embedded Electro-Thermal-Compliant Actuation
Authors: Moulton Timothy , Ananthasuresh G. K.
Published: December 2021

At micro scale, thermal actuation provides larger forces and is easier to control compared to the widely used electrostatic actuation. In this paper, we highlight a third advantage of thermal actuation viz. the ease with which it can be utilized to achieve a novel embedded electro-thermal-compliant (ETC) actuation for MEMS. A number of novel ETC building blocks and devices are described and their analysis and design issues are discussed. The devices were microfabricated using MCNC’s MUMPs foundry process as well as a bulk-micromachining process called PennSOIL (Penn Silicon-On-Insulator Layer). Experimental measurements are presented and reasons for discrepancies with the theoretical predictions are discussed.
Interactions of Nonlinear Permeability and Load Partitioning on Cartilage Mechanical Behavior
Authors: Araj M. J. , Wayne J. S.
Published: December 2021

Partitioning of an applied stress and material properties are two characteristics that can contribute to the longevity of articular cartilage in the demanding environment of diarthrodial joints. A biphasic finite element method (Wayne et al., 1991) predicted the behavior of a simulated joint surface while the load partitioning at the surface to solid and fluids phases (fluid support) and characteristics of the permeability of the tissue were varied. Increasing amounts of fluid support dramatically decreased cartilage deformation and solid stresses. Nonlinear permeability had a similar effect but a large gradient existed at the surface for low fluid support and increasing nonlinear permeability. Nonlinear permeability with high levels of fluid support had a minimal effect.
Dynamic Optimization to Characterize the Energy Efficiency of Kangaroo Locomotion
Authors: Rabinowicz Anna C. , Rodriguez-Monteverde David , Kaplan Matthew L. , Heegaard Jean H.
Published: December 2021

In this study we investigated the energy efficiency of kangaroo locomotion as a function of hopping speed. We tracked the motion of the joints and body segments of the Tammar wallaby (Macropus eugenii) using high-speed digital capture. Kinematic observations revealed that the height of the wallaby’s jump is uncoupled from its velocity for the speed ranges measured. Computing internal torques at the joints during the stance phase revealed a back and forth pattern of torque flow between the lower and upper links.
The Biomechanical Analysis of a Double Bundle Posterior Cruciate Ligament Reconstruction Using Robotic Technology
Authors: Janaushek Marsie A. , Woo Savio L.-Y. , Kanamori Akihiro , Vogrin Tracy M. , Yagi Masayoshi , Harner Christopher
Published: December 2021

The PCL consists of two primary bundles, the anterolateral (AL) and posteromedial (PM). The AL bundle is larger, stiffer, and has a higher ultimate load (Harner, 1995), and has been the focus of PCL replacement surgery (Clancy, 1983). However, clinical outcomes of PCL reconstruction have been unsatisfactory (Lipscomb, 1993); which has led to the question of the advancement of a double bundle procedure in hopes to more accurately reproduce the PCL (Clancy, 1998). It was therefore the objective of this study to evaluate the biomechanics of a double bundle PCL reconstruction (PCL-2), and compare these results with those obtained for the intact knee as well as a single bundle PCL reconstruction (PCL-1). To study this, a robotic/universal force-moment sensor (UFS) testing system which measures the multiple degree of freedom (DOF) knee kinematics determines the in situ force in the ligaments (or replacement grafts) in response to external loading conditions was utilized. The hypothesis was that PCL-2 would improve knee kinematics and in situ forces to those of the intact knee throughout the range of knee flexion as compared to PCL-1.
A Reliable and Accurate Method of Measuring Orthosis-Wearing Time
Authors: Havey Robert , Gavin Thomas , Patwardhan Avinash , Pawelczak Steven , Ibrahim Kamal
Published: December 2021

Orthosis-wearing compliance is considered to be an important factor in the outcome of orthotic treatment for idiopathic scoliosis (Rowe, et al. 1997; Katz, et al. 1997). However, at the present time a reliable and objective method of measuring orthosis-wearing time is lacking. Current estimates are based on self-reported compliance and estimated wear and tear of the orthosis itself. Availability of an accurate and reliable technique to measure how long a patient wears a prescribed spinal orthosis will allow clinicians to objectively study the relationship between patient compliance and outcome of orthotic treatment, and arrive at rational guidelines for prescribing orthosis wearing hours. The purpose of this study was to develop an accurate and reliable method to objectively measure spinal orthosis-wearing time.
Physiological Levels of Substrate Deformation Are Less Stimulatory to Bone Cells Compared to Fluid Flow
Authors: You Jun , Yellowley Clare E. , Donahue Henry J. , Jacobs Christopher R.
Published: December 2021

It is believed that bone cells can sense mechanical loading and alter bone external shape and internal structure to efficiently support the load bearing demands placed upon it. However, the mechanism by which bone cells sense and respond to their mechanical environment is still poorly understood. In particular, the load-induced signals to which bone cells respond, e.g. fluid flow, substrate deformation, electrokinetic effects etc., are unclear. Furthermore, there are few studies focused on the effects of physiological strain (strain < 0.5%, Burr, 1996; Owan, 1997) on bone cells. The goal of this study was to investigate cytosolic Ca2+ mobilization (a very early signaling event) in response to different substrate strains (physiological or supra-physiological strains), and to distinguish the effects of substrate strain from those of fluid flow by applying precisely controlled strain without induced fluid flow. In addition, we quantified the effect of physiologically relevant fluid flow (Cowin, 1995) and substrate stretch on the expression of mRNA for the bone matrix protein osteopontin (OPN). A computer controlled stretch device was employed to apply different substrate strains, 0.1%, 1%, 5% and 10%. A parallel plate flow chamber was used to test cell responses to steady and oscillating flows (20dyn/cm2, 1Hz). Our data demonstrate that physiological strain (< 0.5%) does not induce [Ca2+]i responses in primary rat osteoblastic cells (ROB) in vitro. However, there was a significant (p < 0.05) increase in the number of responding cells at supra-physiological strains of 1, 5, and 10% suggesting that the cells were capable of a biological response. Similar results for human fetal osteoblastic cells (hFOB 1.19) and osteocyte-like cells (ML0-Y4) were obtained. Furthermore, compared to physiological substrate deformation, physiological fluid flow induced greater [Ca2+]i responses for hFOB cells, and these [Ca2+]i responses were quantitatively similar to those obtained for 10% substrate strain. Moreover we found no change in osteopontin mRNA expression after 0.5% strain stretch. Conversely, physiological oscillating flow (20dyn/cm2, 1Hz) caused a significant increase in osteopontin mRNA. These data suggest that, relative to fluid flow, substrate deformation may play less of a role in bone cell mechanotransduction.
Axial-Shear Failure Behavior of Human Femoral Trabecular Bone
Authors: Arramon Yves P. , Yeh Oscar C. , Morgan Elise F. , Keaveny Tony M.
Published: December 2021

An understanding of the failure of trabecular bone subjected to multiaxial loading has relevance in the mechanics of trauma and bone implant interfaces. The development of computer aided tomography-based computer models allow predictions of the mechanical behavior of whole bones when subjected to stress states too complex to be described analytically (Ford et al., 1996; Keyak et al., 1998; Oden et al., 1998). However, these models cannot confidently predict the failure of the trabecular bone without an experimentally validated multiaxial failure criterion.
Isometric Co-Contractions of the Quadriceps and Hamstrings in Intact and PCL-Deficient Knees
Authors: Yang Hongzhi , Li Yi-Chun , Hefzy Mohamed Samir
Published: December 2021

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

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

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

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

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

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

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

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

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

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

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

Interstitial laser photocoagulation (ELP) was performed ex vivo in lean bovine muscle by delivering 1.5 W of continuous-wave 1064 nm Nd:YAG laser energy from a 400 μm core plane-cut optical fiber. The strategy for determining the char temperature involved measuring temperatures where thermal gradients were reduced, and extracting times at which temperature-time profiles displayed interesting nonlinear changes. These times were used to guide a finite difference thermal model, calculating transient temperatures based on two physical descriptions of tissue charring. Modifications in the optical and thermophysical properties due to tissue coagulation (T ≥ 60 °C) and vaporization of tissue water (T ≥ 100°C), respectively, were considered. By placing measured charring dimensions, 2.0 ± 0.3 mm, on calculated temperature-distance profiles, a tissue charring temperature of 414 ± 92°C was estimated.