bluuebunny/crossref_metadata_2025_split huggingface dataset:
Engineering of Complex Systems in the 21st Century
Authors: Crisp H. E. , Franke M. E. 
Published: July 2023

Abstract
A U.S. Navy-initiated annual workshop program for promoting wise technology investment in the engineering of complex systems in the 21st century, especially in systems engineering technology, is described. Descriptions of the first two workshops held in 1994 and 1995, including some general results that were obtained by the focus groups, are given. Because of fundamental changes in the way the Department of Defense (DoD) currently acquires goods and services, the third workshop is designed to couple the focus group discussions and expectations closely with the DoD mandated concepts of Integrated Product and Process Development (IPPD) and Integrated Product Teams (IPTs). Primary focus group tasks related to practices to improve the engineering of complex systems within the IPPD context are discussed. Some characteristics of complex systems are presented. A few recent studies on engineering and management processes and DoD and industry experiences related to engineering of complex systems outside of the workshops are reviewed. Human resources and the changing role of the engineer are discussed.
CAE Durability Simulation of Vibration Sweep Tests
Authors: Hu J. M. , Garfinkel G. 
Published: July 2023

Abstract
This paper presents a simulation method for vibration sweep tests of components and interconnects. The paper introduces the computational method to determine cumulative fatigue damage as a function of the stress-frequency response, the sweep rate and the testing time, demonstrates the “local stress-strain” approach to predict the non-linear (elastic-plastic) stress at the potential failure sites through the linear dynamic finite element analysis in the frequency domain. As an application example, the analysis procedure and computational results for the aluminum wire-bonding between a silicon chip and printed wiring board are presented.
Thermomechanical Stress Analyses of Plated-Through Holes in PWB Using Internal State Variable Constitutive Models
Authors: Fu Chiayu , Ume I. Charles , McDowell David L. 
Published: July 2023

Abstract
In application of multiaxial fatigue theories, extrapolation of concepts developed from uniaxial fatigue research must be used with caution. Previous related research on plated-through hole (PTH) fatigue investigations has been based on so-called effective stress/strain methods, which did not account for the fact that fatigue crack nucleation and growth is observed to occur on specifically oriented planes. Moreover, previous related thermal stress/strain analyses on PTH has been based on so-called bilinear constitutive relations for modeling copper plating with a linear kinematic hardening assumption, and this cannot capture many aspects of cyclic stress/strain behavior during thermal excursions. In this paper, thermal stress analyses using thermodynamics-based constitutive models of metallic consituents of PTHs are conducted by finite element package ABAQUS (1995) for multiaxial fatigue studies. Two types of PTHs (via) are investigated: ordinary empty PTH and PTH with solder filler. Two thermal profiles which simulate temperature fields in service are applied, with one experiencing the glass transition temperature of FR4. Residual stresses generated from previous process temperature history are considered. From the stress analyses, critical plane orientations for tensile type and shear type fatigue cracks are located.
Thermal Management of Flip Chips on Printed Circuit Boards
Authors: Zhang Ron , Peugh Darrel , Myers Bruce 
Published: July 2023

Abstract
The general trend in the automotive electronics industry dictates increased power dissipation on ever shrinking packaged components, giving rise to greater power density. Flip chips on ceramics have long been used for favorable thermal management and reliability. With the drive to cut costs, printed circuit boards are replacing ceramics for many applications, which requires different thermal management techniques. This paper presents some of the techniques that can be used to achieve comparable thermal performance on printed circuit boards.
Polymer Based Flip Chip Interconnect Materials for Monolithic Integrated Circuits
Authors: Strifas Nickolaos , Christou Aris 
Published: July 2023

Abstract
The results of simulation, and material performance testing of anisotropic conductive polymers for flip chip interconnects necessary for power MMICs are reported. The flip chip interconnects are designed to connect source metallization to a common ground plane, and also to provide for heat sinking paths to a ceramic substrate. Finite Element Analysis results are also reported simulating the thermal mechanical stresses present during high frequency operation at a frequency of 1–10 GHz.
Vibration Confinement in a Flexible Truss-Structure
Authors: Choura Slim A. 
Published: July 2023

Abstract
In this paper, the vibration of a flexible truss-structure, described as a finite element model, is confined and suppressed simultaneously using feedback. The structure is assumed to possess regions that are sensitive to vibrations. The control objective is concerned with the isolation of the sensitive regions from vibrational amplitudes. This necessitates the employment of point force actuators for altering the eigenvalues and mode shapes of the structure. The modified eigenstructure of the system allows the confinement of vibration away from the sensitive regions. In order to avoid build-up of vibrational amplitudes during the confinement process, the proposed feedback contains a mechanism for vibration suppression. In addition, the proposed control strategy demonstrates that the vibrational amplitudes associated with the sensitive regions are brought faster to rest as opposed to those associated with the remaining regions of the structure. We show that the confinement-suppression of structural vibration is possible with a reduced amount of actuators whose number is less or equal to the dimension of the structure model.
ℋ∞ Controller Design for Wing/Store Flutter Suppression
Authors: Gade Prasad V. N. , Inman Daniel J. 
Published: July 2023

Abstract
In this paper an ℋ∞ control algorithm is applied to design a feedback system for active wing/store flutter suppression. A two degree-of-freedom model of a typical section of an airfoil with an external store in incompressible flow is used for analysis. A state space representation is obtained by using a second order rational approximation of the complex Theodorsen function. The active suppression concept is based on the classical decoupler pylon technique that involves the use of passive soft spring-damper elements to decouple the wing torsion mode from the store pitch inertia effects. The current approach proposes to use a piezo wafer strut as an active device to desensitize the wing from store pitch effects and to eventually aid in increasing the flutter speed. Due to some modeling simplifications made in the analysis, a controller design is attempted that yields a closed-loop system that is robust in the face of unstructured uncertainties without sacrificing the nominal performance. A mixed-sensitivity problem in ℋ∞ control theory is solved where the issues of robust stability and performance measures are explicitly handled.
Boundary Control of a Flexible Link Electrically Driven Gantry Robot
Authors: Baicu Catalin F. , Rahn Christopher D. , Dawson Darren M. 
Published: July 2023

Abstract
Gantry robots are used for precision manufacturing and material handling in the electronics, nuclear, and automotive industries. Light flexible links require less power but may vibrate excessively. In this paper, an implementable boundary controller is developed to damp out undesirable vibrations in a flexible link gantry robot driven by a brushed DC motor. Hamilton’s principle produces the governing equations of motion and boundary conditions for the flexible link. The electrical subsystem dynamics for a permanent magnet brushed DC motor couple with the link dynamics to form a hybrid ODE-PDE system. Through an embedded desired current control law, an integrator backstepping controller generates the desired control force on the mechanical subsystem. A velocity observer estimates the gantry velocity eliminating one feedback sensor. Numerical simulations using a Galerkin discretized model demonstrate the improved vibration damping characteristics provided by the backstepping boundary control law. Experimental results confirm the theoretical predictions, showing twenty times faster transient decay than PD control with backstepping boundary control.
Vibration Analysis of Slow Speed Machines
Authors: Hussain Mirza S. 
Published: July 2023

Abstract
This paper describes the hardware and data analysis techniques required to diagnose problems in slow speed machines, down to 1.8 RPM. Transducer selection, data collection and the physics of the applied technology are also discussed. Technology to facilitate defect identification, location, size and severity are included. Actual case histories from on-line operating machines are used as examples of each problem. The combination of the frequency spectra and time signal are used for defect identification, and the economics of accurate diagnosis are discussed.
The Application of Optimal Pole Placement Technique in Structural Control
Authors: Chang Chih-Chen , Yu Lung-On 
Published: July 2023

Abstract
An optimal pole placement technique is proposed for the vibration control of a structure modeled as a single-degree-of-freedom (SDOF) system subjected to a white noise ground excitation. The objective of the proposed technique is to shift the closed-loop poles into a prescribed region in the complex plane using the smallest amount of control force variance. The Kuhn-Tucker necessary conditions and second order necessity and sufficiency theorem are used to solve for the control gain and the corresponding optimal pole locations in the prescribed region. With the use of independent modal space control (IMSC) theory, this algorithm is further applied to a single-degree-of-freedom system equipped with an active mass driver (AMD). Numerical results show that the algorithm is efficient and can be used to design the AMD for seismic vibration control of tall building.
Generating Command Inputs to Eliminate Residual Vibration via Direct Optimization and Quadratic Programming Techniques
Authors: Pai M. C. , Sinha A. 
Published: July 2023

Abstract
This paper deals with the construction of optimal command inputs to eliminate residual vibration in a flexible structure with single and multiple modes as well. First, the time-optimal command inputs are generated by direct parametric optimization with Lagrangian multipliers. Next, the command input is generated in the form of a sequence of step commands via the method of quadratic programming in which the sum of squares of step commands is minimized. The results from numerical simulations are presented.
Analytical and Experimental Analysis of a Neural-Based Hybrid Vibration Control for Cable-Stayed Bridges
Authors: Shoureshi Rahmat A. , Bell Mark 
Published: July 2023

Abstract
Intelligent civil engineering structures which posses the capability to resist catastrophic seismic activities and high load degradation are of great interest to the scientific community and to the population at large. This research focuses on vibration reduction in large civil engineering structures using intelligent control techniques and multiple low power actuation devices. Electromagnetic shakers and hydromechanical adaptive filters are utilized as actuation devices. A complex, nonlinear civil engineering structure is considered, mathematically modeled, analyzed, and retrofitted with these actuators for experimental purposes.. A 1/150 scale model of the existing cable-stayed bridge was constructed from aluminum, steel, high tensile strength piano wire, and guitar machine heads (to facilitate cable tensioning) and is mounted on a rectangular steel base. The prototype has a standard cable-stayed bridge design with dual A-frame towers and a fan-type cable arrangement. It has an overall length of 10.5 feet and a tower height of approximately 1.5 feet. It is the goal of this paper to present intelligent control schemes that utilize a fixed controller design for disturbance rejection and uses intelligent adaptive controller to handle small plant perturbations. An adaptive control strategy that encompasses vibration reduction, system identification, hybrid actuation (i.e. the use of active, semi-active, and passive actuators in a single control system), and combined feedforward / feedback control is sought. Intelligent methods of system identification and disturbance prediction are also incorporated. Experimental results obtained from the experimental prototype are presented.
Design Optimisation of a Controllable Vibration Damper for Vehicle Suspension Applications
Authors: Peel D. J. , Stanway R. , Bullough W. A. 
Published: July 2023

Abstract
In this paper the authors consider the problem of optimising the design of a magneto-rheological (MR) damper for controlling the lateral vibrations of a modern rail vehicle. It is shown how, using generalised test data, the primary control variable (i.e. the applied magnetic field) can be related to the desired force-velocity envelope of the MR damper. Optimisation of the damper design is then considered, taking account of the damper dimensions and available space envelope, the dynamics (due to compressibility and inertia) of the MR fluid and the configuration of the magnetic circuit.
Using data from a commercially available MR fluid, it is shown how a controllable damper can be designed to improve upon the specification for a conventional lateral railcar damper. With zero applied magnetic field the MR damper is shown to be capable of providing a fail-safe minimum value of damping. Increasing the magnetic field provides a maximum equivalent damping level in excess of that available from a conventional hydraulic damper. Over the frequency range from 1 to 10 Hz it is suggested that dynamic effects would not cause significant degradation of performance. Furthermore, for the MR fluid considered, the electrical power consumption would be unlikely to exceed 100 watts.
A Linear Theory of Three-Layer Damped Sandwich Shell Vibrations
Authors: Hu Yuh-Chung , Huang Shyh-Chin 
Published: July 2023

Abstract
Generic differential equations of motion for a three-layer sandwich shell with viscoelastic core are derived. The Hamilton’s principle and Donnell-Mushtari-Vlasov simplification are employed in the derivation. The differential equations, unlike the existing models with five displacements, contain only three displacements, that are one transverse displacement and two in-plane displacements of the host structure. The proposed theory is generic and can be specialized to account for many other commonly occurring geometry, such as spheres, cylinders, plates, cones, ..., etc. The theory can be directly applied to the studies of shells / plates with constrained damping (CLD) layer. The theory can also be degenerated into one single layer or two-layer structures. Specialization of the generic theory to cylindrical shell is focused and an example is demonstrated in this paper. The results of one single layer shell agreed well with the classical shell theory. Two-layer shell models proved to be accurate and can be used for the studies of active vibration control and smart material developments.
Design Impact of Piezoelectric Actuator Nonlinearities
Authors: Main John A. , Garcia Ephrahim 
Published: July 2023

Abstract
This paper presents data supporting the need for including the nonlinear effects inherent in voltage control of piezoelectric stack actuators in order to generate accurate system models. The describing function approach was used in this investigation as an example. While the use of the describing functions does improve overall accuracy of the system model, it is demonstrated that the extreme sensitivity of the describing functions to amplitude at low actuator displacements still compromises the accuracy of models of systems that include voltage-controlled piezoelectric actuators.
It is also demonstrated that using charge-feedback control with the piezoelectric actuators makes the need for nonlinear model elements less pressing since the charge control describing functions are much nearer unity than their voltage control counterparts. The charge control describing functions are also less amplitude dependent, so estimates of system performance can be made with greater confidence.
Spatially Distributed Opto-Mechanical Shell Actuators: Opto-Thermoelectromechanics and Control
Authors: Tzou H. S. , Liu B. 
Published: July 2023

Abstract
Non-contact light-activated distributed opto-mechanical actuators represent a new class of distributed actuator which can induce distributed actuation without hard-wire connections. Active distributed control of flexible shells using distributed opto-mechanical shell actuators are investigated in this paper. A generic shell actuation theory is proposed and the governing opto-thermoelectro-mechancial equations of circular cylindrical shells are derived. The systems equations reveal the couplings among elasticity, photodeformation, pyroelectricity, and thermoelasticity. Optimization procedures for sensor/actuator placements to ensure the maximal observability and controllability of selected natural modes are proposed. Application is demonstrated and detailed control effectiveness is investigated. Numerical simulations suggest that the distributed optical actuators are effective for controlling low-frequency modes. Sensor/actuator placements and actuator sizes also dominate the control effectiveness of selected natural modes. Time history analyses suggest the Lyapunov control is more effective than the proportional feedback control.
Control of Semicircular Shells With Thermal Shock and Mechanical Excitations
Authors: Ye R. , Tzou H. S. , Tani J. 
Published: July 2023

Abstract
Shell-type components and structures are very common in many mechanical and structural systems, e.g., nozzles, pressure vessels, storage tanks, rockets, antenna dishes, etc. Modeling and analysis of adaptive piezothermoelastic shell laminates represents a high level of sophistication and complexity. Accordingly, a numerical method is developed to investigate the complicated temperature, mechanical, and control interactions of piezothermoelastic shell composites in this study. Constitutive equations, governing equations, and boundary conditions of a generic piezothermoelastic continuum are defined first. Strain-displacement relations, electric field-potential relations, thermal gradient-temperature relations of laminated shell composites are then defined. A new piezothermoelastic composite triangular shell finite element is formulated and developed. Matrix equations of the piezothermoelastic shell laminate are derived, in which mechanical, temperature, and electric force vectors are also defined. The electric force vector is used in active control of the shell laminates. Finite element solutions of a piezoelectric laminated composite plate are compared with experimental data and numerical solutions first. Distributed control of a piezoelectric laminated semicircular shell subjected to mechanical and temperature (thermal shock) excitations is investigated and control effectiveness evaluated.
On the Relationship Between Active and Passive Mode Localization
Authors: Yigit Ahmet S. , Choura Slim A. 
Published: July 2023

Abstract
Recently, some researchers proposed what is termed as “active mode localization” where all or some of the mode shapes are altered by feedback in such a way that the modes are spatially localized. The resulting closed loop behavior is similar, at least qualitatively, to the phenomenon known as “Anderson localization” or normal mode localization which occurs due to irregularities (disorders) in periodic structures. This study is an attempt to find the relationships between active and passive mode localization. It is demonstrated that similar results can be obtained by either a passive design which exhibits normal mode localization or by an active controller which is obtained by employing some of the recently proposed design methods of active mode localization. It is anticipated that the ideas proposed in this study will be useful in developing systematic methods for integrated structure/control designs.
Computation of Aerodynamic Noise Emitted From a Door Mirror of a Passenger Car and its Synthesis
Authors: Himeno Ryutaro , Fukushima Tatsuya , Ono Kenji 
Published: July 2023

Abstract
The aerodynamic noise caused by an outside door mirror of a passenger car was calculated and synthesized. Flows around the car including the mirror were computed using a finite-difference method and an overlapping grid technique. Sound pressure of the aerodynamic noise in far field from the car was computed with Curie’s formula using unsteady pressure distribution on the mirror which is numerically solved from the incompressible Navier-Stokes equations. The sound is then synthesized for engineers to evaluate. We investigate the relation between noise sources and the flow field, and find that the strong noise sources are distributed along sepalation lines. This means it possible to reduce the noise if we can avoid separation or fix sepalation lines. Considering it, we modified the mirror shape and succeeded to reduce the aerodynamic noise.
CFD Applications of Automotive Heat Exchangers
Authors: Halt David W. , Allan Valerie J. , Fish Garry R. 
Published: July 2023

Abstract
Computational Fluid Dynamics (CFD) results are shown in comparison to test data for a variety of louvered and lanced offset fin configurations commonly used in automotive heat exchangers. An intercooler heat exchanger used with turbocharger systems is also presented. A grid sensitivity study is performed which shows that grid converged solutions for 2D fin calculations can be computed in 16 minutes of HP C110 CPU time with reasonable comparison to test data. Temperature contours and surface heat flux plots show details of the flowfield and indicate areas where heat transfer is inhibited. This CFD procedure can be used to investigate heat transfer issues in other fin designs.
A Primitive Variable Finite-Volume Method for Incompressible Viscous Magnetohydrodynamic Flows
Authors: Agarwal Ramesh K. 
Published: July 2023

Abstract
A recently developed numerical method is employed for computing the numerical solutions of the incompressible Navier-Stokes equations in the presence of a magnetic field. The method is based on the pressure correction approach, but employs a regular grid finite-volume variable arrangement instead of the usual staggered grid arrangement. The pressure equation is derived such that effects which promote the well-known checkerboard instability are not present. A relevant compatibility constraint on pressure is satisfied by Neumann boundary conditions obtained using a vector identity. The transport equations for the magnetic field with solenoidal condition are solved with a similar approach. The unified computational framework is thus developed for the solution of incompressible viscous magnetohydrodynamic flows. Implemented in a second-order-accurate finite-volume code, the algorithm is used to compute the magnetohydrodynamic flow in a pipe. Numerical solution is compared with existing analytical and computational results for various Hartmann numbers.