bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonlinear Coupled Piezoelectric-Mechanical Model of Smart Composites
Authors: Thornburgh Robert P. , Chattopadhyay Aditi 
Published: November 2021

Abstract
A completely coupled piezoelectric-mechanical theory which includes the nonlinear piezoelectric effects is developed for composite plates with embedded or surface bonded actuators and sensors. A higher order laminate theory is used to describe the displacement field in order to accurately capture the effects of transverse shear in moderately thick laminates. The coupling between the piezoelectric effect and mechanical response allows for mutual influence of multiple actuators and transformation of energy between the electrical and the mechanical fields. A new fourth order distribution of electric potential is used to develop an electrical model completely compatible with the assumed higher order strain field. The behavior of actuators subjected to large electric fields is captured using the nonlinear piezoelectric-mechanical coupling terms. The resulting model shows good correlation with available experimental data.
A Generalized Laminate Model for Electro-Mechanical Plates and Shells
Authors: Sealing C. S. , Dasgupta A. 
Published: November 2021

Abstract
A coupled finite element formulation is developed to address heterogeneous electro-mechanical plates and shells whose properties vary through the thickness. The goal is to better approximate the through-thickness variation of the mechanical and electrical fields, without incurring the computational burden of a fully layer-wise theory. This formulation uses a special constraint condition, which makes the transverse gradients of the field variables proportional to the gradation of the material properties through the thickness. The formulation is implemented into a commercial finite element code and used to solve simple test cases. Results are compared with other known methods.
Linear Parametric Models of Tensegrity Structures
Authors: Sultan Cornel , Skelton Robert E. 
Published: November 2021

Abstract
In this paper we derive the linear equations of motion for tensegrity structures around arbitrary equilibrium solutions and cast them in vector second order form. For certain tensegrity structures which yield particular equilibrium configurations easily parameterized we present the corresponding linear models and identify the structure of the linear models matrices in terms of the geometrical and inertial parameters of these structures. Analytical and numerical evidence is presented which shows that these equilibria are stable.
Energy Minimization-Based Vibration Control of a Bridge Using Magneto-Rheological Fluid Dampers
Authors: Liu Yanming , Gordaninejad Faramarz , Evrensel Cahit A. , Wang Xiaojie , Hitchcock Gregory 
Published: November 2021

Abstract
This paper presents vibration control of a scaled two-span bridge structure. Magneto-rheological fluid (MRF) dampers are utilized as the semi-active energy absorbing devices and a bridge vibration control system is developed. Closed-loop control system based on the total energy minimization is used to suppress the bridge deck motion under simple harmonic and simulated earthquake excitation. It is experimentally demonstrated that this closed-loop control system can effectively control the relative displacement and the absolute acceleration of the bridge deck.
Genetic Spatial Optimization of Active Elements on an Aeroelastic Delta Wing
Authors: Richard Robert E. , Rule John A. , Clark Robert L. 
Published: November 2021

Abstract
Reduced-order models of potential-flow aerodynamics have been developed and greatly facilitate the analysis and design of aeroelastic systems in the early design phase. Models capturing 95% of the physics with 8% of the modeling effort can be realized to evaluate various active and passive design considerations. A delta wing model has been developed to determine the most effective locations and shapes for transducers required to provide flutter control. The basic design philosophy is presented based upon an analytical model of the structure. A genetic algorithm was used to determine the optimal transducer locations and shapes required to provide effective flutter control based upon an open-loop performance metric. The genetic algorithm and performance metric essentially provide loop shaping through the adaptive structure design. An experimental model was developed based upon the optimal transducer designs. Wind tunnel tests were performed to demonstrate closed-loop performance for flutter control. Results from this study indicate that a single sensor/actuator pair can be designed to extend the flutter boundary and selectively couple to only those modes required to control the response.
Design of a Piezoelectric Point Actuated Active Aperture Antenna
Authors: Angelino Marc , Washington Greg 
Published: November 2021

Abstract
In this research, the design of a piezoelectric point actuated active aperture antenna is introduced. The antenna consists of numerous piezoelectric point actuators placed perpendicular to the doubly curved aperture. The point actuators are comprised of a piezoelectric element and a stick-slip mechanism used to generate motion. A specially designed code that takes into account the mechanical and electromagnetic effects is used to determine the desired shape of the aperture. The final shape of the aperture is verified using stereo photogrammetry.
Design and Modeling of a Piezoelectric Actuator for Minimally Invasive Surgery
Authors: Edinger Ben , Frecker Mary , Koopmann Gary H. 
Published: November 2021

Abstract
A small-scale piezoelectric actuator has been designed for use in minimally invasive surgery. The actuator is designed to actuate a compliant suture needle grasper as part of a telerobotic surgical system. The actuator consists of a single piezoceramic stack and a slider-crank mechanism which acts as a mechanical stroke amplifier. The main focus of this paper is on the design of the actuator and fabrication and test of a prototype as a proof of concept. The design and fabrication of the prototype actuator is discussed as well as experimental results measuring its performance. A quasi-static model of the actuator which predicts the mechanical amplification and force response is also discussed. Results from laboratory bench-top experiments are presented, and the actuator together with the compliant gripper are shown to grasp and hold a standard suture needle.
Mechanical Models for Insect Locomotion: Parameter Studies
Authors: Schmitt John 
Published: November 2021

Abstract
Motivated by experimental studies of insects, we develop a three-degree-of-freedom, energetically conservative, rigid body model with a pair of elastic legs in intermittent contact with the ground. The resulting piecewise-holonomic mechanical system exhibits periodic gaits whose neutral and asymptotic stability characteristics are due to intermittent foot contact, and are largely determined by geometrical criteria. We study how dynamics depend on physical parameters such as mass, moment of inertia, leg length, leg stiffness, and leg touchdown angle. We develop exact and approximate scaling relations that predict gait scaling in response to individual parameter changes, and suggest that the model is relevant to the understanding of locomotion dynamics across species.
Predictive Control of Nonlinear Mechanical Systems Using a Short-Term Prediction Method Based on Chaos Theory: Applications to a Forced Pendulum
Authors: Masumoto Noriyasu , Yamakawa Hiroshi 
Published: November 2021

Abstract
In this paper, an active vibration control method for nonlinear mechanical systems is presented. The control forces are determined by the future values obtained by a short-term prediction method based on chaos theory and the authors call such a control method a predictive control method. The predictive control method is applied to a system for a pendulum forced by a sinusoidal torque at the supported point. The equation of motion for the pendulum becomes nonlinear when the swing angle is large. It is also known that chaotic behaviors occur in such a nonlinear pendulum model under some conditions. Here, a predictive control method to get the control forces using the angular displacements near future is discussed. In addition, a method is presented to find the optimum sampling period to take samples from the response which is continuous with respect to time. The ideas of forward and backward horizons, defined by the authors before, are also taken to the nonlinear pendulum system, and the effectiveness of the control method is examined numerically.
Relative Stability Analysis for Vibration Absorbers With Multiple Delayed Feedback
Authors: Huang Chang , Olgac Nejat 
Published: November 2021

Abstract
A novel tuning methodology for active vibration absorption is discussed. The underlying proposition is to use partial state feedback with multiple unrelated time delays. The objective of this tuning is to combat excitation forces with multiple frequencies, which are time varying. It is shown that the required control parameters can be evaluated on-line rather rapidly. The system stability aspect however, needs to be resolved a priori to the control actuation. This is the challenge facing this procedure due to the presence of multiple (and mostly “unrelated”) time delays. A new stability assessment methodology, the Directional Stability Chart method, is presented. The outcome of this procedure is used to determine the local stability levels and preferred operating zones in the domain of the multiple excitation frequencies. The method is also expanded to assess the relative stability level of the tuned absorber. Example case is taken from a PZT actuated active absorber. Desirability of the operating points are compared based on the relative stability levels, and the observations are verified by simulations.
Equivalent Active Circuits of Distributed Control Systems
Authors: Tzou H. S. , Ding J. H. 
Published: November 2021

Abstract
Modeling distributed parameter systems (DPS) by electronic circuits and fabricating the complicated equivalent circuits to evaluate the system characteristics always poses many challenging research issues for years. Modeling and analysis of distributed sensing/control of smart structures and distributed structronic systems are even scarce. This paper is to present a technique to model distributed structronic systems with electronic circuits and to evaluate control behaviors with the fabricated equivalent circuits. Electrical analogies and analysis of distributed structronic systems is proposed and dynamics and control of beam/sensor/actuator systems are investigated. To determine the equivalent circuits and system parameters, higher order partial derivatives are simplified using the finite difference method; partial differential equations (PDE) are transformed to finite difference equations and further represented by electronic components and circuits. To provide better signal management and stability, active electronic circuit systems are designed and fabricated. Electric signals from the distributed system circuits (i.e., soft and hard) are compared with results obtained by classical theoretical and other (e.g., the finite element, and experimental) techniques.
The Architecture and Development Environment of Virtual Manufacturing Systems
Authors: Yuan Qing Ke , Chen Xin 
Published: November 2021

Abstract
For adapting the demands of the rapid changing and enhancing the competing capability of enterprise in the international market, various modern manufacturing systems have been put forward, which are aimed at various specifications, perfect performance and high quality, low production cost and short manufacturing cycle of products, virtual manufacturing system (VMS) has been emerged as the times require, which is effective technology to meet the challenge of 21 century’s manufacturing industries. Based on analyzing modern manufacturing systems, according to the characteristics and requirement of VMS, in this paper, the architecture, the key technologies and the implement way of VMS were explored, and development environment for VMS was put forward, which is a powerful tool for building VMS.
Modeling and Experiment on Physical and Chemical Liquid Deposition Processes for Rapid Tooling and Manufacturing
Authors: He Zongyan , Zhou Jack G. 
Published: November 2021

Abstract
A new solid free-form fabrication (SFF) technique, named Physical and Chemical Liquid Deposition (P/CLD), is introduced in this paper, and then several key technical problems are stated. In order to solve these problems, theoretical models to describe the nucleation and growth of deposits in PLD, the chemical dynamic process in CLD, and the heat transfer in P/LCD are studied. To determine the heat transfer parameters, some experiments are designed and experimental results are presented.
Mechanical Characterization of Gold Bonding Wires With Different Doping at Extreme Temperatures
Authors: Mahadevan Dave S. , Hause Vern , Lee Tien-Yu Tom 
Published: November 2021

Abstract
A new process was developed to characterize the mechanical strength of small bonding wires under extreme temperature environment. By the combination of innovative fixture designs and a commercially available mechanical tester, both Beryllium and Calcium doped wires were evaluated for their strengths in the temperature range of −55°C to 250°C. Results indicated that the tensile break strength of Beryllium doped wire decreased with an increase in temperature throughout the temperature range tested whereas for Calcium doped wire it remained generally constant throughout. In addition, percent elongation of Beryllium doped wire significantly increased above 200°C whereas Calcium doped wire exhibited a constant decrease with an increase in temperature. Up to a tensile load of 27.5 grams, both wires were loaded less than their elastic limit under normal operating conditions (−40°C to 150°C). Hence, the cyclic load would not weaken the wire. If that limit is exceeded, Beryllium doped wire would weaken. Calcium doped wire has the advantage of resisting extrusion after the formation of wire bond giving added strength in normal operating conditions.
Quench Process Modeling and Optimization
Authors: Bellur-Ramaswamy Ravi S. , Sobh Nahil A. , Haber Robert B. , Tortorelli Daniel A. 
Published: November 2021

Abstract
We optimize continuous quench process parameters to produce a desired precipitate distribution in aluminum alloy extrudates. To perform this task, an optimization problem is defined and solved using a standard nonlinear programming algorithm. Ingredients of this algorithm include a cost function, constraint functions and their sensitivities with respect to the process parameters. These functions are dependent on the temperature and precipitate size which are obtained by balancing energy to determine the temperature distribution and by using a reaction-rate theory to determine a discrete precipitate particle size distribution. Both the temperature and the precipitate models are solved via the finite element method. Since we use a discrete particle size model, there are as many as 105 degrees-of-freedom per finite element node. After we compute the temperature and precipitate size distributions, we must also compute their sensitivities. This seemingly intractable computational task is resolved by using an element-by-element discontinuous Galerkin finite element formulation and a direct differentiation sensitivity analysis which allows us to perform all of the computations on a PC.
Viscoplastic Constitutive Modeling of Anisotropic Damage Under Nonproportional Loading
Authors: Chow C. L. , Yang X. J. , Chu Edmund 
Published: November 2021

Abstract
Based on the theory of damage mechanics, a viscoplastic constitutive modeling of anisotropic damage for the prediction of forming limit curve (FLC) is developed. The model takes into account the effect of rotation of principal damage coordinates on the deformation and damage behaviors. With the aid of the damage viscoplastic potential, the damage evolution equations are established. Based on a proposed damage criterion for localized necking, the model is employed to predict the FLC of aluminum 6111-T4 sheet alloy. The predicted results agree well with those determined experimentally.
Calculation of Punch Force and Maximum Pressure for Tube Extrusion
Authors: Zhang S.-H. , Shang Y.-L. 
Published: November 2021

Abstract
Punch force and maximum pressure for tube extrusion can be predicted with an upper bound theory-based program POLSK. Experiments of steel tube extrusion and wax physical modeling were performed. The punch force and the maximum pressure values were obtained. Comparisons were made among the experimental results, physical modeling results and upper bound predictions. It was found that a medium extrusion coefficient causes the lowest pressure on the tooling system, very low and very high extrusion coefficients can both cause very high pressure. It is proved that the upper bound predictions are in good agreement with the experimental results and the upper bound program is suitable for use of steel tube extrusion design.
A Stabilized Mixed FEM for Viscoplastic Flow Analysis
Authors: Liu Yong , Maniatty Antoinette M. , Klaas Ottmar , Shephard Mark S. 
Published: November 2021

Abstract
A stabilized, mixed finite element method for viscoplastic flow analysis is presented. Preliminary results show promise for modeling steady-state bulk forming processes. In this work, the Ladyzenskaya-Babuska-Brezzi (LBB) condition is circumvented by adding mesh dependent terms (stabilization terms), which are functions of the residual of the Euler-Lagrange equations, to the usual Galerkin method. The stabilized formulation and applications to plastic flow problems are presented. Numerical experiments using the stabilization method show that the stabilized, mixed FEM is effective and efficient for non-linear steady forming problems.
Real-Time Process Characterization of Open Die Forging for Adaptive Control
Authors: Nye T. J. , Elbadan A. M. , Bone G. M. 
Published: November 2021

Abstract
Open die forging is a process in which products are made through repeated, incremental plastic deformations of a workpiece. Typically, the workpiece is held by a manipulator, which can position the workpiece through program control between the dies of a press. The part programs are generated with an empirically derived parameter, called the spread coefficient, whose value is subject to some contention. In this work, we demonstrate how process information can be used in real time to derive the actual spread coefficient for a given workpiece as it is being formed. These measurements and calculations occur in real time, and can be used to regenerate part programs to optimize the forming process, or can be used to adaptively control each incremental deformation of the workpiece.
Solid Freeform Fabrication by Ultrasonic Joining: Implementation and Mechanical Analysis
Authors: Gao Yuan , Greif Robert , Doumanidis Charalabos 
Published: November 2021

Abstract
This article presents the mechanical analysis of an emerging nonthermal Rapid Manufacturing technology for layered fabrication of metallic or multiple-material products, i.e. the Multi-material Ultrasonic Adhesion process, based on Ultrasonic Welding. Its laboratory implementation, automation and integration, and parameter optimization are described first. The mechanics of Ultrasonic Welding, the stress and strain field changes during one weld, and static and dynamic behavior of the weld material are then analyzed. The technical advantages of Ultrasonic Welding for the manufacturing industry include fabrication of dense, full-strength functional solid metal parts, multiple-material composites, and active parts with embedded intelligent components and electronic, mechatronic, optic and fluidic structures.
Development of a MicroPCM Machine Coolant
Authors: Colvin David P. , Colvin Virginia S. , Bryant Yvonne G. , Whitney Ray A. , Sheikh-Ahmad Jamal Y. , Bailey John A. 
Published: November 2021

Abstract
Under multiple SBIR (Small Business Innovation Research) programs from the Department of Defense, NASA and the National Science Foundation, investigators at Triangle Research and Development Corporation (TRDC) and associated universities have conducted research toward the development of a new machine coolant that has demonstrated some significant advantages. Results in SBIR programs for NASA, USAF and NAVY, that were reported in earlier publications, have indicated that both aqueous and non-aqueous two-component coolants containing microencapsulated phase change materials (microPCMs) can provide from 10× to 40× (1,000% – 4,000%) enhancement in the coolant’s effective thermal capacitance along with isothermal heat transport and significant improvement in the system’s Nusselt Number. During another SBIR program for the National Science Foundation, a non-aqueous, two-component microPCM machine coolant was used for machine turning operations and demonstrated (a) an increase in the effective thermal capacitance of a machine coolant oil by more than 10× or 1,000%, (b) a significant reduction in the temperature of a work/tool thermocouple as much as 15%, (c) a reduced temperature excursion of the machining coolant by more than 90% for the same cutting speeds and feed rates, (d) a significant reduction in the tool force by 25 to 75%, and (e) a highly significant reduction in the environmental pollution in the shop due to much lower evaporation of the machine coolant. The further development of such a microPCM machine coolant could potentially (a) significantly increase tool life (related to the thrust force), (b) improve product quality, dimensional accuracy and tolerance, and (c) reduce both coolant loss and operator exposure to hazardous evaporating coolants during high-speed machining operations. Follow-on experiments at General Motors have also demonstrated that microPCM coolants can be used effectively during grinding operations.
Integration of Mechanical and Biological Criteria When Defining Injury Tolerance
Authors: Lotz Jeffrey C. , Bass Elisa C. , Wagner Diane R. 
Published: November 2021

Abstract
Degeneration of the intervertebral disc is an important clinical and socio-economic problem. Because of associations between injury rates and physical activity, mechanical factors are thought to play an important role in the incidence and progression of this disease. Bioengineers have historically utilized a strength-of-materials approach to develop tolerance criteria and design interventions meant to reduce injury risk. However, it has become apparent that the disc’s biologic response to loading is an important determinant of degeneration rate. In order to quantify degeneration risk, a hierarchical approach is required which links whole body mechanical exposures to tissue responses that are consistent with the clinical presentation. One challenging aspect of this approach is the definition of accurate constitutive relationships for disc tissues, which are inherently nonlinear, anisotropic and heterogeneous. A second challenge is the development and interpretation of models that allow assessment of the in vivo biologic response to loads. Recent progress in these areas indicates that mechanical and biological factors should be quantitatively linked to provide a comprehensive injury tolerance criteria.
Bubble Nucleation Under External Pressure in Nitrogen-Polystyrene Microcellular System
Authors: Kumar Vipin 
Published: November 2021

Abstract
Polystyrene disks were saturated with nitrogen at 2000 psi pressure (13.8 Mpa) and foamed at 115 C in a pressurized cavity. It was found that the cavity pressure had no influence on the cell nucleation density. This was a surprising result, since based on classical nucleation models, we expected fewer and fewer cells to nucleate as we increased the cavity pressure.