bluuebunny/crossref_metadata_2025 huggingface dataset:
An Overload Failure of a Dental Prosthesis: A 3D Finite Element Nonlinear Contact Analysis
Authors: Prabhu Ajit A. , Brunski John B.
Published: March 2022

Dental implants are extensively used to treat fully and partially edentulous patients. However, the success rates of clinical cases involving partially edentulous patients is lower than the fully edentulous cases.1 In one partially edentulous case that we have been examining, a prosthesis was supported by two screw-shaped, 3.75mm diameter Branemark implants as shown in Figure 1. The implants were separated by 7mm and were located in the molar region of the mandible. After the insertion of the implants and a healing period of 6 months, the prosthesis was put into function. After 3 months of loading, there was significant bone loss near the mesial implant which eventually lead to its mechanical failure. We have previously made a biomechanical analysis of this failed implant case using analytical2 and 3D finite element (FE) analysis.3 In the previous 3D FE study, the interface between the implant and the bone was assumed to be fully bonded. In this current investigation, the assumption of bonding vs no bonding is further investigated using 3D contact analysis. Surface to surface contact is a phenomenon that occurs between two contacting surfaces which are close to each other and might be in contact or separated depending on the interfacial stresses between the two surfaces. In this study the contact analysis is used to capture the bonding and non bonding between the bone and the implant interface.
Effects of Knee Flexion Angle and Quadriceps Contraction on Hamstrings Co-Contraction
Authors: Hefzy Mohamed S. , Yang Hongzhi , Abdel-Rahman Eihab M. , Alkhazim Mohamad
Published: March 2022

Open and closed kinetic chain exercises are being used as knee rehabilitation regiments. These exercises are designed to strengthen the muscles around the knee in order to improve its stability. Following a knee injury and/or surgery, the patient is asked to perform an isometric contraction of the quadriceps as the very first task of the rehabilitation process. Co-contraction of the hamstrings may occur depending on the amount of quadriceps contraction and the angle of knee flexion at which this isometric contraction is performed. The purpose of this study is to determine the effects of the knee flexion angle and the quadriceps tension on the amount of hamstrings co-contraction that occurs during an isometric contraction of the quadriceps muscles.
The Effect of Strain on Collagen Fiber Orientation in Ligament: A Morphometric Study
Authors: Kukreti U. , Belkoff S. M.
Published: March 2022

Collagen is the primary structural component in soft connective tissues. Collagen molecules are organized into fibers which appear crimped or wavy when the tissue is in a stress-free state [1]. As the tissue is stretched, the crimping pattern diminishes as the fibers align in the direction of the applied load [2]. It is generally accepted that the sequential straightening of collagen fibers is responsible for the mechanical behavior exhibited by soft tissues. Several mathematical models incorporate this uncrimping phenomenon to describe the characteristic nonlinear behavior of biological tissues [3,4,5]. Although the models describe the mechanical behavior well, it remains unknown exactly how the collagen fiber orientation changes with strain.
Mechanics of Cell Rolling Adhesion in Shear Flow
Authors: Lei Xiaoxiao , Lawrence Michael B. , Dong Cheng
Published: March 2022

Leukocyte rolling along endothelial cells is a critical step of leukocyte-endothelium interaction, which plays important roles in tissue inflammation and wound healing [1]. The occurrence of rolling results from the dynamic balance of hemodynamic shearing force acting on the cell and adhesive bond force between cell and endothelium, while the balance strongly depends on the leukocyte deformability [2]. The objective of this study is to elucidate the effects of (1) hydrodynamic shear stress, (2) cell deformation, and (3) surface adhesion strength on the rolling adhesion event through in vitro experiment and theoretical simulation.
Substrate Effects on the Intrinsic Mechanical Properties of Individual Cells
Authors: Shin Daehwan , Schmitz John , Lee Tim , Athanasiou Kyriacos
Published: March 2022

Cells interact with specific molecular components of the extracellular matrix via cell surface receptors [1]. The principal cell surface receptors that mediate cell-extracellular matrix interactions are termed integrins [2, 3]. Integrins are transmembrane receptors that interact with several intracellular proteins, including elements of the cytoskeleton by cytoplasmic domains. Therefore, integrins serve as a molecular linkage between the extracellular matrix and the cytoskeleton. Some investigators have suggested that many of these vital cellular activities are regulated, at least in part, by intercellular and intracellular forces that are generated by a continuous molecular connection that includes components of the extracellular matrix, integrins, and cytoskeletal elements (i.e., f-actin, microtubules). It is believed that individual cells “sense” and generate forces transmitted through the extracellular environment by these intricate linkages [4]. Furthermore, this linkage, referred to as the “extended cytoskeleton,” could provide a mechanical signaling mechanism that may underlie many vital cellular activities, including gene expression. It is apparent that the physical properties of a cell may also be affected by this mechanism. Thus, cells grown on different extracellular matrix substrates should be expected to vary their cytoskeletal architecture and have concomitant changes in their biomechanical properties. The objectives of this study were 1) to obtain the intrinsic material properties of the individual cell as a function of the type of substrate matrix and therefore, 2) to investigate fundamental aspects of the response mechanism of individual cells to alterations in their biophysical environment.
A Poroelastic Model of Streaming Potential and Interstitial Fluid Flow in Ligament and Tendon
Authors: Chen Chih-Tung , Vanderby Ray
Published: March 2022

Collagen fibrils are the major component of ligament and tendon and affect the surrounding interstitial fluid flow. These parallel fibrils hold a considerable amount of water and have anisotropic mechanical properties (Frank et al., 1987). Fibril population and tissue porosity are non-uniformly distributed and contribute to the unique micro-hydrodynamics and electrokinetics of ligament and tendon (Frank et al., 1987; Chen et al., 1996). A poroelastic model is extended from a previous study (Chen and Vanderby, 1996) to describe the pore pressure, fluid velocity, and streaming potential under different loadings.
Dynamic and Transient Nonlinear Behavior of Articular Cartilage in Unconfined Compression
Authors: Fortin M. , Soulhat J. , Shirazi-Adl A. , Hunziker E. B. , Buschmann M. D.
Published: March 2022

Functional mechanical behavior of cartilage can be investigated by testing excised tissue in confined, unconfined or indentation geometries using creep, stress relaxation and dynamic sinusoidal tests. Potential nonlinear behavior of cartilage has been mostly characterized in confined compression [1,2]. The extent to which the nonlinearities are intrinsic to the tissue or depend on the specificities of the testing configuration of confined compression is not known. We have therefore performed experimental and analytical tests of articular cartilage in unconfined compression to reveal linear and nonlinear behavior. We found equilibrium stress responses to behave linearly, but transient or dynamic stress responses to be nonlinear. Transient compressive responses stiffened nonlinearly when increasing the static offset compression present at the beginning of the step. On the contrary, dynamic stiffness decreased (weakened) nonlinearly when the amplitude of sinusoidal displacement, imposed on a static offset, was increased. We also found that the articular cartilage nonlinearly maintained a compressive stress when a release displacement was applied from a 10% static offset compression, suggesting possible physiological roles of these nonlinear behaviors.
Development of an In Vitro Experimental Protocol to Study the Extensional Mechanics of the Cervical Spine
Authors: DiAngelo Denis J. , Faber Henry B. , Dull Scott T. , Jansen Thomas H.
Published: March 2022

A sequence of in vitro experiments were performed on a fresh human cadaveric cervical spine to determine a particular set of end mounting configurations and appropriate ranges of load and motion that replicated in vivo sagittal motion and mechanics. The specimen was mounted in a programmable testing apparatus and tested in three different configurations. A combination of translational / rotational motion at the upper fixture and a fixed lower base was found to closely reproduce the in vivo coupled, sagittal motion and loading behavior of the cervical spine.
Dynamic Analysis of 3D Whole-Body Models in Asymmetric Lifting Tasks
Authors: Li Yi-Chun , Lavender Steven A. , Natarajan Raghu N. , Andersson Gunna B. J. , Amirouche Farid M. L.
Published: March 2022

Lifting materials and objects manually or so-called Manual Materials Handling (MMH) is a frequently and physically demanding activity in many industrial and service settings (building construction, mechanical repair of equipment, baggage and package handling, patient handling, fire fighting, etc.). Manual lifting is also the primary cause of overexertion injuries.1
Effects of an Anterior Interbody Fusion Device on Bone Density Distributions in the Lumbar Spine
Authors: Grosland Nicole M. , Goel Vijay K. , Grobler Leon J. , Griffith Steven L.
Published: March 2022

Recently, threaded cylindrical metallic cages have been developed to facilitate anterior interbody fusions. Although, implanted clinically, the long term biomechanical effects of such a device, are not entirely clear. The BAK Interbody fusion system (Spine-Tech Inc., Minneapolis, MN) possesses the ability to impart increased stability, while simultaneously reducing complications associated with the use of autogenous bone grafts. In an effort to predict the potential long term effects of the device, we specifically sought to evaluate the adaptive response of the vertebral bone adjacent to the cage in axial compression and bending modes, via finite element analyses (FEA).
The Determination of the Effect of Lift Characteristics on Dynamic Performance Profiles During Manual Material Handling (MMH) Tasks
Authors: Khalaf Kinda A. , Parnianpour Mohamad , Sparto Patrick J. , Barin Kamran , Simon Sheldon R.
Published: March 2022

When investigating manual material handling (MMH) tasks, such as lifting, the quantification of the various kinematic and kinetic parameters of the lift is an important step towards assessment of functional capacity and development of a biomechanical profile of task demands [1]. The kinematic and kinetic parameters of performance are vector quantities that are often expressed as a percentage of the duration of the lifting cycle. In order to study the effect of lift characteristics (load, mode, and speed) on the dynamic parameters of performance, appropriate statistical analysis should reflect their vectorial constitution as a percentage of the lift duration rather than the traditional method of using descriptive and inferential statistics based on collapsing the data over the cycle. The objective of this study is to develop the methodology for quantifying and evaluating the variability in performance of the motion patterns resulting from different lift characteristics during MMH tasks.
Interactive Image Guided Surgery: The Experience of Wayne State University
Authors: Li Qinghang , Zamorano Lucia , Jiang Zhaowei , Holdener Hans J. , King Paul , Diaz Fernando
Published: March 2022

Stereotactic localization using multimodality of medical images (such as CT or MRI) is increasingly employed to guide neurosurgical procedures 1,2,3,5. This technique provides highly accurate intraoperative localization and allows the surgeon to resect a lesion in its entirety while sparing critical areas of the brain. Image guided interactive frameless stereotaxy has been successfully applied to intracranial surgery and spine surgery. It has demonstrated a potential for reducing both operative time and morbidity. In this paper we described our interactive image guided surgery system and the experience of appling to different kind of surgery.
Heart Assist Devices Equipped With Ionic-Polymeric-Platinum Composite Artificial Muscles
Authors: Shahinpoor Mohsen
Published: March 2022

Reported are the characteristics of some newly developed ionic polymeric-noble metal composites such as Perfluorinated Sulfonic Acid-Platinum composites exhibiting low-voltage, electrically-controlled distributed large motion and sensing capability mimicking biological muscles. Reported further are modeling, design, fabrication and testing of a number of heart assist devices, i.e., LVAD (left ventricular assist devices) equipped with these muscles and activated by a computer-controlled voltage signal generator such as micro-processor controlled heart pace maker. The proposed designs include a pleated jacket made with such artificial muscles and worn by a weak heart with sleeves around the Aorta, Pulmonary and other pertinent veins such as the coronary veins around the heart. The model also presents an electrodynamic analysis of the synchronous contraction of the artificial muscles wrapped around the heart with the heart muscle itself similar to dynamic cardiomyoplasty.
Real-Time Contact Pressure in a Solid Ankle-Foot Orthosis
Authors: Nowak Michael D. , Abu-Hasaballah Khamis S. , Cooper Paul D.
Published: March 2022

Ankle-Foot Orthoses (AFOs) are used extensively for a variety of clinical issues, including the prevention of diabetic foot ulcers. One of the major causes of these ulcerations is the abnormally high plantar pressures present as a result of compromised foot function (Ctercteko, 1981). The AFO alleviates these abnormal pressures by redistributing them to low-pressure plantar regions. While effective, these AFOs are often not used by the patient due to weight and comfort issues. The first step in improving the basic AFO design is to understand the interaction between patient and AFO. Although studies examining and quantifying foot contact pressures in different foot wear under various conditions are innumerable, a very small number of studies measured pressures in a small portion of AFO-Foot contact surface and no studies have examined the foot contact pressures in an entire AFO. This could perhaps be due to the technical difficulties encountered when attempting to instrument an entire AFO surface. The purpose of our study was to determine all AFO-subject contact pressures during different daily activities such as walking, rising from and sitting on a chair, stair climbing and pivoting on the AFO. Real-time contact pressures were obtained for the entire AFO-subject area using the FSCAN pressure measurement system. These results would aid in the design of better AFOs by using these pressures as inputs to the design model.
Articulated External Ankle Fixation: Effect of Hinge Axis Position on Joint Kinetics
Authors: Bottlang Michael , Marsh J. L. , Brown T. D.
Published: March 2022

Articulated external fixation of the ankle joint has been used for the treatment of tibial pylon fractures, with encouraging results [1]. However, problems exist with ankle stiffness, limited range of motion, and calcaneal pin loosening [2].
Enhanced Solid Ankle-Foot Orthosis Design: Real-Time Contact Pressures Evaluation and Finite Element Analysis
Authors: Abu-Hasaballah Khamis S. , Nowak Michael D. , Cooper Paul D.
Published: March 2022

Adult neuropathic diabetic patients with acquired foot deformities such as flat foot and Charcot feet often develop plantar foot ulceration, leading to extended hospital procedures. These ulcerations are attributed to elevated plantar contact pressures (Ctercteko, 1981). A recent preventative means is to fit the patient with a custom made ankle-foot-orthosis (AFO) designed to reduce these pressures. Although effective, AFOs have poor patient compliance due to their high weight.
An Elastic-Plastic Material Model for the True Stress-Strain Behavior of Ultra-High Molecular Weight Polyethylene in Tension and Compression
Authors: Kurtz Steven M. , Jewett Charles W. , Moalli John E. , Edidin Avram A.
Published: March 2022

Prediction of stresses and strains for orthopaedic total joint replacement components depends upon accurate knowledge of the true stress-strain behavior for ultra-high molecular weight polyethylene (hereafter polyethylene), which has been investigated in uniaxial tension but not yet in uniaxial compression. Previous research has suggested that the maximum strains in tibial components are less than 0.12 [1]. An exponential model has been shown to accurately describe the tensile true stress-strain behavior of polyethylene up to 0.12 true strain [2], but no distinction has yet made between the linear elastic and nonlinear plastic regions of the true stress-strain curve.
New Fabrication Techniques for Polymeric Intravascular Coronary Artery Stents
Authors: Nelson Kevin D. , Su Solomon , Phansalkar Anagha R. , Romero Andres A. , Ye Yun-Wei , Eberhart Robert C. , Landau Charles , Meidell Robert S.
Published: March 2022

A new procedure has been developed to fabricate polymeric intravascular stents for improved gene/drug delivery. These new stents have been mechanically tested for drug loading capacity, resistance to transluminal pressure collapse, and flexion. They were found to be superior to previous versions of these stents.
A Micro-Structural Constitutive Model for Chemically Treated Bovine Pericardium
Authors: Sacks Michael S.
Published: March 2022

Chemically treated bovine pericardium (BP) has been used extensively in the fabrication of bioprosthetic heart valves (BHV), which have compared to mechanical valves, superior fluid dynamical properties. However, BHVs continue to suffer limited long-term durability and will fail in 8–10 years, as result of calcification and mechanical damage. Our long-term goal is to improve BHV functional performance through the development of improved constitutive models. These models lead to a better understanding of the role tissue microstructure in determining overall mechanical behavior and limited long-term durability.
Haptic Rendering of Surfaces Defined by Implicit Functions
Authors: Salisbury Kenneth , Tarr Christopher
Published: March 2022

This paper presents a method for computing the contact forces which must be imposed on a human (via a haptic interface) to evoke the sensation of touching surfaces described by implicit equations of the form S(p) = 0. The algorithm computes in real-time the forces of interaction which would arise from a point interacting with a real surface of the given shape. It models the forces of interaction which would arise when contacting linearly elastic material with surface friction. At each instant, a tangent plane to the surface at the contact point is computed and used to track the contact point’s motion and prevent it from passing though the surface. A method using cutting planes to limit the extent of these surfaces is described. Though the rendering techniques are presented in the context of implicit surfaces, they can be applied to other classes of surfaces.
Influence of Haptic and Visual Displays on the Estimation of Virtual Environment Stiffness
Authors: Durfee W. K. , Hendrix C. M. , Cheng P. , Varughese G.
Published: March 2022

Human subject experiments were performed to determine the influence of a visual display on the perception of haptic spring stiffness. Seven subjects participated in an experiment where they were presented with two virtual springs and asked to determine which was stiffer. The virtual springs were represented through a graphics display which they watched and a haptic display which they explored with their fingers. The relative visual to haptic stiffness was varied over a range. The results demonstrated that when subjects made errors in haptic stiffness estimation (which they did approximately 41% of the time), those errors tended to follow visual rather than haptic cues, particularly when the visual to haptic stiffness mismatch was large (30–40%). The results suggest that in some cases, visual cues can be used in virtual environments to compensate for deficiencies in haptic displays.
Estimation and Interpretation of Mechanical Impedance in Robotic Processing of Inhomogeneous Material
Authors: Gu J. H. , de Silva C. W.
Published: March 2022

Mechanical impedance can be quite useful in robotic processing of objects. It represents properties of the material being processed. Robotic tasks that handle inhomogeneous material may be controled based on impedance information. This paper addresses impedance estimation in a mechanical processing task that employs a robot. The method uses existing motion sensors and actuator current sensing for robot “effort” in computing mechanical impedance, and fuzzy logic for interpretation of the impedance information. A Kalman filter is developed to estimate mechanical impedance based on a mathematical model of a joint drive-motor, in the time domain. A parameter identification method is utilized to estimate impedance parameters based on a process impedance model in the frequency domain. Impedance information, in both time domain and frequency domain, is interpreted for use in high level task control employing fuzzy logic and fuzzy associative memory. The technique is applied to a robotic fish processing system in the Industrial Automation Laboratory.
Computer Aided Modeling of Induced Strain Actuators and Other Piezoelectric Structures
Authors: Bouchilloux Philippe , Letty R. Le , Lhermet N. , Claeyssen F.
Published: March 2022

The complexity found in the structure and operation of piezoelectric devices continues to increase, and, at the same time, designers are placing a greater emphasis on a more global approach to the design of such devices. In this paper we present and summarize the methodology for a more global approach to the design of piezoelectric devices that was developed at Magsoft Corporation and Cedrat Recherche.

Because it can accurately solve coupled-field problems, the finite element method (FEM) is the most suited numerical method available to produce efficient models of induced strain structures. Other parts of the piezoelectric devices, such as their drive electronics and control loops, must also be modeled. A computer aided electrical network analyzer is undoubtedly much more suited for this purpose. Therefore, we have combined these two computer aided techniques (FEM and electrical networks), and in this paper we show that it is possible to perform accurate simulations of complex mechatronic devices.

In this paper we also describe some applications and explain how they are currently being studied at Magsoft Corporation and Cedrat Recherche. This is illustrated with examples taken from the fields of: piezoelectric actuating and sensing, precise positioning, active damping of vibrations, and piezoelectric motors design. The results obtained from the design of these applications are encouraging and prove that our design methodology, more global and using the combination of different computer aided modeling tools, is valid.
Virtual Instrumentation for Intelligent Sensors: Development, Production and in the Field
Authors: Brignell John E. , Taner Ali H.
Published: March 2022

Recent contributions to the realisation of intelligent sensors are recapitulated. In particular the benefits of reconfigurability and virtual instrumentation techniques are highlighted. It is then shown that such techniques can be extended from the development phase into the production and field phases of sensor life. In this way the potentially dire effects of complexity can be greatly mitigated.
Fuzzy Logic Expert System for Automatic Tuning of Myoelectric Prostheses
Authors: Bonivento C. , Davalli A. , Fantuzzi C. , Terenzi S.
Published: March 2022

The paper presents a software package for automatic tuning of control parameters of myoelectric prosthesis. The prosthesis system is the INAIL artificial arm controlled by a microprocessor using myoelectric signals acquired from skin-surface electrodes placed on the patient muscle stump.

Usually, qualified staff is necessary for control parameters set-up and subsequent recurrent adjustments, and therefore patients are forced to come back frequently at prosthesis factory laboratories.

The proposed software interacts with unskilled patients and automatically set up the control parameters of the prosthesis using qualified staff knowledge stored in a Fuzzy Logic Expert System (FLES).

In this paper the software package is presented and some preliminary results from its application are discussed.
The Work of Breathing in a Nonlinear Human Lung Model
Authors: Athanasiades A. , Ghorbel F. , Clark J. W. , Niranjan S. C. , Liu C. H. , Zwischenberger J. B. , Bidani A.
Published: March 2022

Work of breathing (WOB) functions associated with the mechanics of breathing are identified, based on a nonlinear model of the human lung and using a Lagrangian approach. Total and dissipative WOB values are computed numerically for three spontaneous breathing maneuvers (tidal, panting and forced vital capacity) of the same subject. An additional simulation reveals the effect of changing lung tissue compliance on WOB. The energy analysis provides valuable insight into the mechanics of respiration, and, in particular, the significance of individual model components. It provides the basis for sensitivity and optimization studies of the respiratory function, especially in the context of evaluating ventilator-dependent patients.
Vibration Cancellation in Complex Support Structures for Precision Robots
Authors: Rhim Sungsoo , Book Wayne
Published: March 2022

This paper examined the effectiveness of the Optimal Arbitrary Time-delay filter applied to cancel the undesired elastic modes of vibration in complex supporting structures for a precision robot which is under development. To achieve the desired positioning precision, suppressing the structure vibration is essential. For this to be done Optimal Arbitrary Time-delay (OAT) filtering method was chosen. Modeling of the system has been performed and using this model, simulations were done without and with the OAT filter. The ability of OAT filter to cancel the vibration of the structure was demonstrated in the simulation results. To verify the simulation, an experiment including an OAT filter within the robot control system has been done on the current version of the precision robot. Even though the dynamic response of the supporting structure in the precision robot system is inherently of small magnitude and high natural frequency, response due to the filtered command showed that the filter successfully reduced vibration in magnitude and got rid of the residual vibrations faster than the response with the unfiltered command.
Sliding Mode Control of a Magnetically Levitated Fast-Tool Servo System
Authors: Gutierrez Hector M. , Ro Paul I.
Published: March 2022

Magnetic Servo Levitation (MSL) is currently being investigated as an alternative to drive fast-tool servo systems that could overcome the range limitations inherent to piezoelectric driven devices while operating over a wide bandwidth. To control such systems, a feedback-linearized controller coupled with a Kalman filter has been described. Performance limitations that degrade tracking accuracy suggest the use of a more robust controller design approach, such as sliding mode design. Current literature on sliding mode deals almost exclusively with systems that are affine on the input, while the magnetic fast-tool servo is nonlinear on it when the control action is current command. This paper discusses two sliding mode-based controllers, one that overcomes the aforementioned problem by using a modified sliding condition to calculate control action, and a second one that uses affine control command by operating in voltage mode.
Control of I.C. Engines for Emissions and Idle Speed Regulation
Authors: Shah Minesh A. , Franchek Matthew A.
Published: March 2022

Presented in this paper is a controller design methodology for simultaneously regulating engine idle speed and air-fuel ratio in the presence of an external non-measurable torque load disturbance. Hammerstein type models are used to characterize the nonlinear dynamics associated with the air and the fuel entrainment process. A feedback and feedforward control approach based on describing functions is used to achieve the performance goal of maintaining the engine idle speed within a prespecified output tolerance while limiting excursions in the air-fuel ratio.
Model Predictive Control for Active Suspensions: Controller Design and Experimental Study
Authors: Gopalasamy Srinivasan , Osorio Carlos , Hedrick Karl , Rajamani Rajesh
Published: March 2022

This paper discusses the design of a Model Predictive Controller for a vehicle active suspension system and presents the experimental results obtained in the evaluation of the controller performance. The Model Predictive Control methodology described here, utilizes the road profile ahead of the vehicle as preview information and also takes into explicit consideration the physical constraints on the suspension travel. The advantages in the use of preview information in active suspension control have been studied by several researchers. The explicit consideration of the physical limits on the suspension travel becomes an important factor under rough road conditions such as the ones encountered by off-road vehicles. A computationally efficient version of the predictive controller was developed so as to be implementable on-line. The experimental evaluation of the controller was performed on the UC Berkeley Active Suspension Test Rig.
Fuzzy Logic Semi-Active Control of a Suspension for Off-Road Vehicles
Authors: Kashani Reza , Strelow Joseph E.
Published: March 2022

A fuzzy-logic approach to semi-active vehicle suspension design is developed, with the goal of improving the speed of the vehicle over very rough, off-road, terrain. The ride metric used for quantifying improvements is the absorbed power of the sprung mass of the vehicle. Particular attention is made to the proper modeling of the suspension using both the full kinematic constraints and the more convenient two degree of freedom model of the quarter vehicle suspension. Nonlinearities of the suspension, including tire stiffness and bumpstops are included at all stages to demonstrate the controller performance advantages. The semi-active control law is developed on the less complex model, and the results of tuning in the fully constrained environment are compared.

The results of this work have broad appeal, from the ease of development of the fuzzy-logic based algorithms, to the cost effectiveness of the semi-active hardware implementation. Improvements in the performance of the suspension system are desirable to the increasingly popular sport utility and light truck markets, as well as to military and emergency vehicle designs.
Statistical Energy Analysis Model and Connectors for Automotive Vibration Isolation Mounts
Authors: Byam Brooks P. , Radcliffe Clark J.
Published: March 2022

Consumer comfort is a top priority in today’s vehicle design. Reduction of noise and vibration enhances comfort and improves the overall quality of the vehicle. Linear elastic vibration isolation mounts are traditionally applied within complex structures to combat noise and vibration. Statistical Energy Analysis (SEA) is becoming an established and tested noise and vibration modeling methodology that is frequently used to model the flow of noise and vibration in complex structures. A SEA model of a linear elastic vibration isolation mount is developed here which enables SEA analysis of elastically isolated systems for the first time.

A vibration isolation mount model has been absent from SEA models because of the lack of an SEA formulation. Linear elastic vibration isolation mount SEA equations are developed here for the first time. The basis of SEA theory is energy sharing among vibrational mode groups. Traditionally, vibration isolation mounts were thought of as compliant elements with no modes suitable to SEA analysis. An example mount is defined and the number of energy storage modes computed. The results show that a linear elastic vibration isolation mount should be modeled in SEA analysis and provide the equations for a SEA isolation mount model. Also included is the analysis for three unique SEA connectors, a mount to acoustic volume connector, a beam to mount connector, and a mount to flat plate connector.
Velocity Profiles Through and Over Arrays of Impermeable Cylinders
Authors: Bijeljic B. , Sederman A. G. , Mantle M. D. , Gladden L. F. , Papathanasiou T. D.
Published: March 2022

We study experimentally (through the non-intrusive technique of Magnetic Resonance Imaging - MRI) and computationally (using the Boundary Element Method - BEM) the distribution of fluid velocities across square arrays of uniform cylinders placed inside a Hele-Shaw cell and oriented with their axes perpendicular to the direction of flow. To simulate the presence of gaps between mold walls and preform in liquid composite molding applications, the cylinders are placed in such a way that an open channel, narrow enough to force a significant part of the flow through the array but wider than the distance between individual cylinders, exists in one side of the array. We are interested in the distribution of velocity in these systems and in particular, the distribution of flow between the two regions (that is, the ‘open’ channel and the cylinder array) and in any velocity transitions from the ‘open’ channel to the interior of the array. Both experimental and computational results show that, for the size of cylinders studied, this transition is complete within the first row of cylinders. Thus, we have not been able to detect any transitions from open-channel flow to flow inside the cylinder array; this will require use of larger number of smaller cylinders. Model predictions are in reasonable agreement with measurements; the observed discrepancies point towards stringent design requirements for such flow cells if the obtained information is to be quantitatively useful.
Ensemble Averaging Technique in the Mechanics of Suspensions
Authors: Buyevich Yu. A. , Theofanous T. G.
Published: March 2022

An approach based on ensemble averaging ideas is elaborated for suspensions of fine particles in a Newtonian fluid. Both field conservation equations and constitutive laws are derived within a unified theoretical frame. The structural form of the field averaged equations of conservation and interpretation of their various terms, particularly phase stresses and interphase interaction force constituents, are clearly revealed. The approach is suggested as an effective paradigm for better understanding of and extending to more complex multiphase flow and heat transfer situations.
Rheological and Thermal Properties of Phenolic Resin and Polymeric Isocyanate and Their Blends
Authors: Bakhtiyarov Sayavur I. , Overfelt Ruel A.
Published: March 2022

Viscous and thermal properties of a phenolic resin (Part I) and a polymeric isocyanate (Part II), and their blends were investigated by using rotational viscometry. The elastic properties of the blends were investigated by means of a jet thrust technique, using a straight tube. The rheological and thermal properties of the blends were dependent on the blend composition. Although both materials are Newtonian liquids, their blends exhibit non-Newtonian liquid flow behavior and elasticity. A thermo-reaction has been observed and investigated after mixing the two parts.
Numerical Prediction of the Molding of Composite Parts
Authors: Dupret F. , Verleye V. , Languillier B.
Published: March 2022

This paper concerns the prediction of the effect of Hele Shaw flow upon the orientation of a suspension of short fibers. A numerical method to solve the decoupled free boundary flow problem and to calculate the fiber orientation is elaborated. Recent developments in the theory of the 3D natural closure approximation are presented and discussed.
Finite Strain, Visco-Elastic Constitutive Models for Kinematically Constrained Materials
Authors: Martin Todd A.
Published: March 2022

The manufacture and increasingly widespread use of thermosetting/thermoplastic pre-preg fabrics suggests that new finite strain material models are needed to describe their behaviour during forming. Determining the appropriate models to apply involves the correct description of the anisotropic visco-elastic behaviour of these materials and the development of methods for measuring the material properties. This paper addresses the former issue, by presenting a logical method for formulating the equations of state for an incompressible continuum reinforced with inextensible fibres. Utilising body tensor fields and the internal variable concept, various thermo-rheological constitutive models are derived, based on the free energy and the dissipation function, which arise naturally in the Clausius Duhem inequality. The inherent assumptions leading to the finite strain Maxwell and Kelvin-Voigt material models are discussed. The method outlined here is general, therefore it allows the formulation of constitutive equations with a clear understanding of the limitations embodied in the resulting models.
Electrorheological Fluids Under AC and DC Excitation and the Influence of Solid Phase Size
Authors: Sproston John L. , Wahed Ali K. El , Stanway Roger
Published: March 2022

This paper is concerned with an experimental investigation of a comparison of the rheological performance of an ER fluid in oscillatory squeeze-flow under DC and AC conditions. The fluid is sandwiched between two parallel plane electrodes, the upper one stationary and the lower one oscillating normal to its plane. The magnitude of the transmitted force across the fluid in the AC case is seen to be highly dependent on the shape of the input waveform and on the electrical excitation frequency. In all cases this force is found to be smaller than that seen in the corresponding DC case.

It is seen that the performance of the ER fluid depends dramatically on the size of the dispersed solid phase and has an optimum value which is dependent on the inter-electrode gap. Finally the implications of the results to vibration control and the trend of future work into squeeze flow behaviour are discussed.
On Short Wave Elastic Instabilities in Parallel Plate Flow
Authors: Olagunju David O.
Published: March 2022

The purely elastic instability of torsional flow a viscoelastic fluid confined between two coaxial parallel plates is considered. This problem is analyzed in the limit of small aspect ratio α = h/a, and zero Reynolds number where h is the plate separation and a is the plate radius. In this limit we derive a set of equations which can be solved analytically for the Oldroyd-B model. Our analysis shows that stability is controlled by a local elasticity number ε≡rλ2ϖ2/α, where r is the local radius, γ is the relaxation time and ϖ is the constant rotation rate. For ε less than some critical value εc the flow is linearly stable. As ε increases past this critical value the flow loses stability to a time dependent oscillatory mode. The most dangerous mode has a short wave length of the order O(α). Our results are in good agreement with those of Oztekin and Brown (1993) and Byars et al. (1994). A criterion to ensure stability to infinitesimal disturbances is proposed.
The Effect of Temperature and Humidity Exposure on Adhesion
Authors: Pearson R. A. , Hydro R. M. , Lloyd T. B. , Nied H. F.
Published: March 2022

Silver-filled organic adhesives are commonly used in the microelectronics industry to bond silicon chips to a wide variety of substrates. The substrates include copper, silver, nickel / palladium, polyimide, and glass-filled epoxies. In this presentation, we will examine the effect of temperature and humidity exposure on the adhesive strength between silver-filled epoxies and copper leadframe substrates. Both a mixed-mode bending specimen (MMB) and a width-tapered double cantilever beam specimen (WT-DCB) are used to determine the adhesive strength in terms of an interfacial strain energy release rate (interfacial fracture energy). The interfacial fracture energy is found to decrease significantly at high temperatures (230 C, which is typical for solder reflow) and after 168 hrs humidity exposure (85 %RH / 85 C). The origins for this behavior will be discussed.
Reliability of Underfill-Encapsulated Flip-Chip Packages
Authors: Doi Hiroaki , Kawano Kenya , Yasukawa Akio , Sato Toshihiko
Published: March 2022

Reducing the plastic strain in solder joints is necessary to prolong the life of the joints during the thermal cycling test for flip-chip packages. Without heat spreaders, it is known that underfills with suitable mechanical properties reduce the plastic strain in the solder joints for underfill encapsulated flip-chip packages. From the stress analyses of the heatspreader fixed packages, it is shown that although the heat spreader increases the strain in the joints, the underfills also have an effect on the reduction of the joint strain. Furthermore, the mechanical properties of the underfill that produces the least strain in the joints are the same as those for packages without heat spreaders.

For the heat spreader fixed package, the delamination between the solder joint and the chip surface occurs. This is caused by the extension of the delamination in the interface between the underfill and the chip surface. From the stress analyses, it is made clear that this delamination is due to the stress in the underfill at the edge of the chip and this stress is significantly affected by the fillet shape of the underfill.

Thermal cycling tests were conducted to relate the FEM analysis results with those of the tests. The effects of the heat spreader, the mechanical properties of the underfill, and the fillet shape of underfill on the mode of fracture and the life of the solder joint are investigated.
Stress Analysis of High Density Bare Chip Packaging Technologies
Authors: Tsukada Yutaka , Mizumoto Shogo , Kodama Yasuyuki , Nishimura Hideo
Published: March 2022

A bare chip packaging with an encapsulated flip chip joint on an epoxy base carrier is now emerging into an electronic packaging industry due to its high density, high performance and low cost capability. Generally, one of the key points of the bare chip packaging is to overcome thermal stress caused by a mismatch of coefficient of thermal expansion (CTE) between the chip and carrier. Initially, a ceramic carrier was used because of its low CTE which minimizes the mismatch of CTE. A technical break through was made to use an epoxy base carrier as the chip carrier instead of ceramic one by resolving a large CTE mismatch with an epoxy encapsulant which fills the space between the chip and carrier [Tsukada et al., 1992].

This technology is basically applied to implement a package of bare chip attach on mother board and now expanding to provide a chip attach in a BGA package. Though such packages are become to be used for various products, the reliability characteristics are not sufficiently explored yet. This paper describes the solder joint life comparison as the one of such items between these two package types, bare chip and BGA on planar, and two way of assembling to carrier, single side and double side assembly.
Comparison of Acoustic Microscope, X-Ray Radiography, Dye Penetrant and Destructive Physical Analysis Data for Die Attachment Analysis
Authors: Gilmour Duane A. , Reilly James F. , Calabrese Donald W.
Published: March 2022

This paper addresses the analysis of die attach disbonds (delaminations) of silicon die in a multichip module (MCM). A silicon die attached to a silicon substrate in an MCM requires good adhesion for thermal dissipation and reliability purposes. Traditionally, die attach is evaluated by destructively measuring adhesion or non-destructively measuring voiding through x-ray radiography. For this paper, non-destructive acoustic microscopy and destructive dye penetrant testing were used to supplement the x-ray radiography. A sample in which x-ray radiography showed little die attach voiding had significant die attach disbonds at both the die/die attach interface as well as the die attach/substrate interface. The disbonds were identified by the acoustic microscope. Interpretation of the acoustic microscopy data proved complex and required careful comparison of the C-mode images generated with the A-scans at specific locations. The nature of the disbonds at the A-scan locations was confirmed using dye penetrant testing, metallurgical cross section and optical microscopy. The disbonded areas can change the thermal dissipation characteristics and mechanical stress distribution of the sample and indicate processing problems. X-ray radiography is effective for determining density variations or voiding in the die attach and acoustic microscopy is effective for determining interface characteristics and the combination of the two techniques provides an excellent approach for evaluating die attach in MCM’s. These techniques can be applied to interfacial analysis of other structures and can be used to characterize interfaces for modeling and establish evaluation criteria for non-destructive process monitoring.
A Model for Predicting the Precipitation Strengthening Response of Precipitation Hardened Alloys Strengthened by Ordered Precipitates
Authors: Fragomeni James M. , Hillberry Ben M.
Published: March 2022

A model was developed for predicting the precipitation hardening response of a particle strengthened alloy determined from the microstructure, composition, and heat treatment. The precipitates in the microstructure which impede dislocation motion and control the precipitation strengthening response as a function of the aging practice were used as the basis for determining the strength depending on the actual size distribution of particles. The particle size and distribution were determined from the microstructure via the heat treatment and composition. Consequently a micromechanical model was determined for predicting the variation in yield strength with aging time, temperature, and composition. The overall micromechanical model which was determined from the particle coarsening kinetics, dislocation mechanics, thermodynamics, resolved shear strength, as well as the particle strengthening mechanisms based on the dislocation particle shearing and dislocation particle looping interaction mechanisms was used to predict the strength of the demonstration alloy based on the microstructure. The demonstration alloy selected as the vehicle to model the precipitation strengthening response was a particle strengthened aluminum-lithium-zirconium alloy. Using this demonstration alloy, the overall model predicted from the microstructure the variation in strength with aging time, aging temperature, and composition, in the underaged, peak-aged, and overaged heat-treatments. The predicted aging curves were in good agreement with the experimental results for different aging practices.
Study on Robust Fail-Safe Structural Design Method
Authors: Hiroyasu Tomoyuki , Shoji Maho , Yamakawa Hiroshi
Published: March 2022

The designs of structures, such as bodies of cars, hulls of ships, and frames of buildings, can be roughly divided into two flows: those are the upper flow and the lower flow of the design process. In this study, the new structural design method called “Robust Fail-safe Structural Design Method” is proposed for structures that are designed in the upper flow of the design process. By this method, the Young’s modulus and the topology of the structures are determined simultaneously. The designed structures also have the characteristics of robustness and fail-safe. The numerical example is shown to demonstrate to design a structure by this method. In the numerical example, some candidates of the robust fail-safe structures are derived and the problems are discussed.