bluuebunny/crossref_metadata_2025_split huggingface dataset:
Two-Dimensional Finite Element Thermal Stress Analysis of Butt Adhesive Joint in Steady Temperature State
Authors: Nakagawa Fumito , Sawa Toshiyuki , Nakano Yuichi , Katsuo Masahide 
Published: July 2023

Abstract
Thermal stresses of butt adhesive joints in steady temperature state are analyzed using a two-dimensional finite element method (FEM). The results obtained are as follows. The maximum principal thermal stress in the adhesive layer decreases when the ratio of thermal conductivity of an adhesive to that of an adherend approach I. When both adherends arc in the same temperature state, the maximum principal thermal stress in the joint decreases with a decrease of the adhesive thickness. When both adherends are in different temperature states, the maximum principal thermal stress varies with the ratio of the adherend thickness to the adhesive thickness. The maximum principal thermal stress in the joint which is subjected to the uniform temperature change AT is smaller than that in the joint in which the temperature difference of free surfaces of both the adherends is AT. In the experiments, the adhesive layer of the butt adhesive joint was modeled by an epoxide resin plate. The thermal stresses of the joints under steady temperature state were measured by two-dimensional photoelastic experiments. Fairly good agreement was seen between the numerical and the experimental results.
The Interaction of Crack and Creep in Cross-Ply Composites
Authors: Gao Zhanjun 
Published: July 2023

Abstract
For cross-ply laminates micro-matrix cracks in the 90° plies and creep deformation of the 0° and 90° plies are two forms of damages which affects the long-term durability of the materials. In this paper, a general framework for the analysis of cross-ply laminates with matrix cracks and creep deformation is proposed. For this purpose admissible stress fields are constructed which satisfy equilibrium and all boundary and interface conditions. The principle of minimum complementary energy is utilized to derive a differential equation for the stress function from which the stress field of the composite can be derived. The inhomogeneous term of the differential equation involves the creep strains which are loading history dependent. The Green’s function of the differential equation is then obtained. Using the Green’s function and a constitutive equation, two-dimensional stress and strain states in the composites at any time are represented through an integral of the Green’s function and the accumulated creep strains. This new analysis takes into consideration the microcrack-microcrack interaction, as well as the interaction between the microcracks and the creep deformation, and provides a point-wise stress field instead of average stress field as most of the analytical approaches yield.
The interactions of matrix cracks and creep deformation of an eight-harness satin weave (8H SW) Nextel 610/Aluminosilicate ceramic matrix composite is studied using the proposed model. The predicted creep strain of the composite shows good correlation with experimental data at different levels of temperature and stress conditions.
Experimental Study of Rotor Blade Tip Clearance Control Utilizing Smart Structure Technology
Authors: Lin Y.-J. , Wen C. , Choi B. , Saravanos D. 
Published: July 2023

Abstract
In this paper the experimental development of a simple and effective vibration control scheme for a flexible cantilever beam employing smart structure technology is presented. Our goal is to develop a physically realizable means to actively control turbine rotor blade tip vibration with piezoceramic sensors and actuators. To include the flexible characteristics of rotor blades in our analysis, a flexible cantilever beam is used to simulate the dynamic behavior of the turbine blades due to external disturbances, generated by a magnetic shaker. The shaker was installed near the free end of the flexible beam to maximize the external excitations. Piezoceramic sensor and actuator were used and evenly distributed as elements of the smart structure. The mathematical model of the smart structure including the piezoceramic sensors and actuators was determined by combining both analytical and experimental schemes. Based on the derived experimental dynamic model, a proportional gain feedback controller was implemented to compensate for the vibratory deflections of the underlying structure. The results of the work show that the proposed control methodology along with the smart structure can suppress more than 80% of the measured structural vibration, which is considered satisfactory.
The Selection of Diagnostic Technologies and Sensors for Condition Based Maintenance Systems
Authors: Nemarich Christopher P. , Hegner Henry R. , Natishan Marjorie Ann E. 
Published: July 2023

Abstract
The effective implementation of Condition Based Maintenance (CBM) systems generally requires the use of sensors selected specifically to detect, isolate and diagnose machinery component faults. In order for CBM systems to operate reliably, the diagnostic technologies and sensors used to monitor the machinery must provide repeatable and accurate measurements. The ability of a CBM system to effectively detect and correctly identify component faults at their inception depends largely on the appropriate selection of the fault parameters to be measured and the sensors used to measure them. Furthermore, the incorrect selection, inappropriate application, or inattention to the sensor performance requirements may lead to missed failure detects and false alarms, resulting in the general lack of acceptance of the entire CBM system. This paper presents an overview of a methodology for the selection of applicable diagnostic technologies and sensors for machinery health monitoring systems.
Reliability-Centered Maintenance Approach Applied to a Pipeline
Authors: Checkwitch Kerry S. , Glover Alan G. , Van Hardeveld Thomas 
Published: July 2023

Abstract
A recent business process re-engineering effort undertaken at NOVA Gas Transmission Ltd. provided an opportunity to completely review and improve upon strategies and methodologies used in the maintenance of a very complex natural gas transportation system. In order to achieve safety and reliability in an expanding and aging system, a completely new approach to maintenance planning was adopted based on a Reliability-Centered Maintenance strategy. This is the first application of this approach to a gas transportation system. Development of this maintenance methodology, its major components, and specifically how it has been applied to a pipeline are discussed. The integration of this strategy into a complete pipeline integrity management system allowing full assessment of all hazards specific to the pipe is also reviewed. Examples of results and benefits from the first systems analyzed using this new approach are presented.
The Briar Patch: From DoD to Commercial Systems Engineering
Authors: Hale Pat 
Published: July 2023

Abstract
Most of us are familiar from childhood with the Uncle Remus story where Br’er Rabbit escapes being the main dinner course by imploring his captor to “Throw me in that briar patch!”. Following defense secretary Perry’s initiative to move DoD toward commercial standards and best practices, many DoD systems engineers have wondered what distinguishes commercial systems engineering from traditional aerospace processes and practices. This paper describes the experiences and observations from a DoD systems engineer’s transition into a pure commercial product development environment. Topics include: What is ‘commercial’ systems engineering? What practices from DoD provide the highest added value in the commercial world? What are the unique challenges to application of systems engineering in the commercial world? What lessons can DoD learn from commercial industry? And, finally, is this commercial ‘briar patch’ a viable future address for you as an aerospace-trained systems engineer?
Why Mechanical Subsystems Are Difficult to Integrate
Authors: Segalman Daniel J. , Ortiz Keith , Wesner John W. 
Published: July 2023

Abstract
Though the theme of System Engineering is integration, and it is normal to attempt in integration to ignore the lines between disciplines, there are distinct characteristics of the mechanical design portion of any major system design project that make this difficult. How these characteristics compound the difficulty of integration is discussed and means to minimize the associated obstacles are suggested.
Developing High Technology Spacecraft in a Severely Cost Constrained Environment
Authors: Euler Edward A. 
Published: July 2023

Abstract
Traditionally, the development of high technology spacecraft for the U.S. Government has been a relatively long duration, high cost activity. A step by step serial process from concept development through manufacturing and test was carefully followed with voluminous documentation, rigorous reviews at each major milestone, and a thorough test and independent quality check of each component and assembly produced. This process has evolved over many years because successful first time operation is so critical. With spacecraft, there is no second chance after a failure. Before the relatively recent emergence of a commercial spacecraft market, the only customers were the U.S. Government (DoD and NASA) who indirectly controlled the development process to insure that technical performance has always been the top priority with cost and schedule significantly lower in importance.
Cure Kinetics for Conductive Adhesives
Authors: Mei Yuhai , Wu Sean , Yeh Chao-pin 
Published: July 2023

Abstract
Conductive adhesives as solder replacement play more and more important role in surface-mounting technology. The magnitude and duration of cure cycle temperature significantly influence the final physical and mechanical properties of the joints. Therefore, a knowledge of the reaction kinetics is essential for relating the physical properties to the extent of reaction of the system. A series of isothermal tests was processed, and the experimentally obtained results were checked against the proposed kinetic model. A modified kinetic model is proposed to describe the rate of degree of cure, and a good agreement was found between modeling and test results.
Finite Element Vibration Analysis for Zero Inserting Force Socket
Authors: Chiang Kuo-Ning , Fu Hsueh-Horng 
Published: July 2023

Abstract
In this research, a vibration analysis using finite element method with specific application to CHIP, LCP socket and PCB packaging are studied. The sensitivity of the design and material parameters of the whole CPU connector system is studied by two different approaches. A coarse finite element model is established to investigate the effects of vibration modes of the boundary condition parameters, and a detailed finite element model is adopted to evaluate the influence of the different types of boundary constrains to the whole system.
Step Soldering Factors Affecting the Reliability of Ag-Pd Thick Film Conductor Pads
Authors: Pan Tsung-Yu , Blair Howard D. , Mitlin David , Crosbie Gary M. , Nicholson John M. , Hangas Jon 
Published: July 2023

Abstract
One of the essential thick film materials on the hybrid circuit is the conductor which performs as an interconnection between discrete components. However, metallurgical reaction between the conductor and solder during the soldering or thermal aging/cycling may cause electrical failure and/or loss of adhesive strength due to the reaction of Ag/Pd with Sn and subsequent intermetallics formed. A step soldering process, which applies a high-Pb solder layer over the conductor layer before the eutectic or near-eutectic Sn-Pb solder is applied, has been shown to prevent contact between the conductor and Sn in the solder, as long as the high-Pb layer does not dissolve into the low-Pb layer. Experiments were carried out to quantify the isothermal interdiffusion reaction rate and the interface displacement between the 88Pb-10Sn-2Ag and the eutectic 63Sn-37Pb solder layers between 195 and 235°C. The results were analyzed by the methodology developed by Lommel and Chalmers (1959) which was based on Nernst-Brunner theory of dissolution (Moelwyn-Hughes, 1947). The displacement of the interface follows an Arrhenius relationship with an activation energy of 98 KJ/mole, which is close to the activation energy of solid Sn diffusion into Pb. A process window was constructed to show that temperature is a more sensitive parameter influencing the reaction rate than time. A mathematical model was applied to predict the interfacial displacement during the reflow process and was found to correlate well with experimental results.
Perspectives for Practical Application of Active Control of Noise and Vibrations in Passenger Cars
Authors: Moreggia Vittorio 
Published: July 2023

Abstract
Several active sound and vibration control systems have been proposed for noise and vibration in automobiles, including In-Cabin Silencing systems for the “volumetric” reduction of engine or rolling noise inside the passangcr compartment, Active Engine Mounts for the reduction of structural vibrations in the car body, induced by the engine cycle, as well as “at source” ASC systems for noise radiated by the air induction and gas exhaust discharge orifices.
The paper overviews the implementation of experimental vehicles, the test resultes and the perspectives for application in mass-produced series. Emphasis is given to a comparative evaluation of the performances of In-Cabin Silencing, Active Engine Mounts and counterrotating engine balance shafts, for the abatement of engine “booming” noise in passenger cars.powered with 4-cilinder-in-line engines.
Active Control of Rolling Noise in a Passenger Car Through Structural and Acoustic Control
Authors: Banfo Gian Luca , Dehandschutter Wouter , Schmidetzki Rainer 
Published: July 2023

Abstract
Within the Brite-Euram Project “Anrava” several active control systems have been evaluated in order to reduce the road noise generated inside the cabin of a mid size station wagon during driving condition on different road surfaces. Different control strategies (feedforward with local and global control, pure feedback) and different approaches (active structural acoustic control and active noise control) have been tested on the car in laboratory conditions and the control performances have been evaluated. The final control strategies, that have been resulted from this study, are based on an adaptive feedforward control algorithm: six accelerometers provide the reference signals and 4 microphones placed inside the cabin give the error feedbacks. Two control configurations, each using a different kind of control sources, have been retained: the structural acoustic control system which works with 6 inertial shakers positioned through the main vibration transmission paths, the anti-noise system with 4 loudspeakers inside the cabin.
The paper describes the approaches utilized to design the different control systems and examines the results obtained during laboratory and road tests comparing them with the predicted performances based on numerical simulations.
Feedforward Active Vibration Control of the Axially Moving String With General Boundary Conditions
Authors: Ying S. , Tan C. A. 
Published: July 2023

Abstract
Active vibration control of an axially moving string by space feedforward control is presented. The problem is formulated to allow considerations of general boundary conditions, which are important from both practical and experimental viewpoints. Closed-form results for the transverse response of both the uncontrolled and controlled string are given in the s domain. The space feedforward controller is established by employing the idea of wave cancellation. The proposed control law indicates that vibration in the region downstream of the control force can be cancelled. Moreover, the control forces are expressed only in terms of measured response and are not explicit functions of the boundary conditions which in general cannot be easily determined. Stability conditions of the controlled system and characteristics of the control forces are also derived and discussed. Simulation results show that the response of the string to both sinusoidal and random excitations is suppressed by applying the space feedforward control.
Implementation of DR and DFFDR Techniques on Distributed Systems
Authors: Olgac Nejat , Elmali Hakan , Hosek Martin , Renzulli Mark 
Published: July 2023

Abstract
The Delayed Resonator (DR) and Dual Frequency Fixed Delayed Resonator (DFFDR) are newly introduced control techniques for active vibration absorption. Both methods propose a delayed position feedback within the absorber portion of the structure to impart ideal resonance features to the absorber. When installed on an oscillating body, they become ‘notch filters’ at their resonance frequencies against excitations on the primary structure. The DR absorber is shown to be real time tunable to the time varying disturbance frequencies. This article addresses the verification of these methods in high frequency ranges. Experiments are conducted on a steel beam to verify the analytical findings. Piezoelectric actuators are used to generate harmonic disturbances and also to implement the control. Encouraging correspondence between the theoretical and experimental findings is observed as well as effectiveness of the DR and DFFDR absorption techniques.
Comparison of Active and Semi-Active Vibration Controllers for a Dragline Boom
Authors: Clark William W. , Kim Sung Hwan 
Published: July 2023

Abstract
This paper compares three semi-active control techniques to two fully-active control methods in suppressing transient vibrations of a dragline, a crane used for excavation. The fully-active methods include full-state feedback optimal control and direct-velocity feedback control, and are used as the benchmarks in the comparison. The semi-active techniques include simple damping, stiffness, and hybrid damping/stiffness controllers. The semi-active methods are selected such that they could be practically implemented on the dragline. The paper first looks at the control methods as applied to a single degree-of-freedom system in order to demonstrate their techniques, then the methods are applied to a 50th-order model of a dragline. The performance of each controller is quantified by several measures, and the feasibility of implementing semi-active control in a large flexible structure such as the dragline is discussed.
Parametric Control of Structural Vibrations via Adaptable Stiffness Dynamic Absorbers
Authors: Lai J. S. , Wang K. W. 
Published: July 2023

Abstract
An energy-based algorithm is developed for dynamic absorbers with adaptable stiffness to suppress structural vibrations via real-time parametric control actions. A controller with multi-objective fuzzy logic is created to reduce the main structure energy while constraining the total system energy. An adaptive-passive supervisor is designed to provide guidelines for implementing the control law. It is proved that the system using this supervisor is globally stable in the sense that all signals involved are bounded. The performance of the controller is demonstrated on a beam example. It is shown that the structure energy level and vibration amplitude can be suppressed effectively.
Sensing/Control of Shell Symmetrical Modes Using Diagonal Line Sensors/Actuators
Authors: Zhong J. P. , Tzou H. S. , Tani J. 
Published: July 2023

Abstract
With the recent introduction of spatially distributed piezoelectric transducers, distributed sensing and control of distributed parameter systems, i.e., elastic continua, can be realized in real physical systems. Since the transducers are spatially distributed in nature, sensor/actuator shapes are crucial to their spatial sensing and control characteristics. This paper is to present a new class of distributed line sensor/actuator specifically designed for sensing/control of shell symmetrical modes. Electromechanics of the line sensor/actuator is discussed and the membrane and bending contributions are analyzed. Sensing and control effectiveness of cylindrical shells are evaluated.
Hybrid Controller for Vibration Suppression: Integrating Physical and Modal Information Using Fuzzy Reasoning
Authors: Greif Robert , Asdigha Mehran 
Published: July 2023

Abstract
Independent Modal space Control (IMSC) is a well established method in active control of vibration. In this method, the control law is developed exclusively in the modal space, allowing for independent design of modal control forces. These forces are then transformed to the physical space by modal transformation. The resulting controller is fixed-gain, with the active damping introduced to the system determined independently for each mode. This damping is directly proportional to the modal velocity in the under-damped case. In this work, we propose to modify IMSC using kinetic energy distribution in the modal space, and fuzzy reasoning. The result is a new non-linear control law, embedding fuzzy reasoning and an implicit fuzzy rule-base that transforms the standard algorithm from a fixed-gain, to a variable-gain controller. A variant of the new algorithm uses information about the velocity profile across the sensed locations to distribute the active damping rationally among the modal controllers. This new algorithm complements the local view of the traditional algorithm in the modal space, with a global view of the velocities in the physical space. The results show significant improvement in the settling time as the performance criterion.
Hybrid Feedforward/Kalman-Filter Controller for Reaction Force Suppression
Authors: Clark William W. , Kim Joo H. , Shelley Franz J. 
Published: July 2023

Abstract
This paper presents a method for actively controlling dynamic reaction forces in flexible structures subject to persistent excitations. The motivation is provided by applications in which dynamic loads result in structural or machinery failures (for example, in the bearings of rotating machinery), or in situations where transmitted vibrations degrade the performance of a system or process. This work is a deviation from much of the vibration control work which focuses on suppressing structural displacements instead of forces.
The controller is based on an adaptive feedforward disturbance cancellation scheme which has come to be a commonly used method among researchers for persistent disturbance cancellation. In order to use that method for control of forces, however, some modifications are necessary. First, since reaction forces are not typically measured in structures, a Kalman filter state estimator is developed to provide the reaction force signal to the feedforward algorithm, and second, the residual flexibility matrix is used in conjunction with the Kalman filter in order to provide accurate force estimates in spite of a reduced-order model. This paper presents the development of the reaction forces, the Kalman filter estimator, and the hybrid feedforward control law, and applies the overall method to a flexible beam test rig to suppress the dynamic reaction forces at its supports.