bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Spatial Matrix Identification as a Practical Inverse Problem in Mechanics
Authors: Okuma Masaaki , Oho Tatsuya
Published: January 2022

This paper presents a method for identifying a set of spatial matrices, which are the coefficient matrices of equations of motion for mechanical structures in the physical domain. The input data for the method are a set of frequency response functions measured experimentally within a limited frequency range of interest and the coordinate data of measurement points. This is a practical engineering inverse problem. The definition of the inverse problem and the method developed are presented in this paper. In addition, a simple example is shown to demonstrate its practical validity and usefulness.
An Interactive Learning Tool for Dynamic Systems and Control
Authors: Lee Kok-Meng , Daley Wayne , McKlin Tom
Published: January 2022

Although there are many stimulating and practical applications for system dynamics and automatic control, students often find the material too abstract, too mathematical, and difficult to master when it is presented in lectures. The difficulties experienced by students in learning system dynamics and controls include the following: (1) Dynamic and control systems are interdisclipinary in nature and require complex mathematical expressions that were taught in previous courses. (2) Computer simulation and hands-on experiments are necessary in order for the students to fully appreciate the basic concepts of automatic control. (3) Lecture hours are insufficient to provide both the theory and real-world applications of system modeling and automatic control. In order to overcome these problems, an interactive multimedia software tool that allows the students to explore the design space was developed. We discuss here the role of technology as it can be applied in teaching system dynamics and control. The primary goal of this work is to build a tool that assists students in learning system dynamics and control by providing a link between control system design (CSD) theory and laboratory learning. Specifically, the materials developed provide support in three different forms of instruction; labs, lectures and homework.
Anticipating Dynamic Loads in Handling Objects
Authors: Wing Alan M. , Flanagan J. Randall
Published: January 2022

In this paper we review a set of studies showing that when people pick up and move an object they continually adjust their grip force in order to stabilize the object in the hand. These grip force adjustments occur simultaneously with or slightly ahead of fluctuations in load forces and torques related to moving the object. They may therefore be seen as anticipatory and we argue that a key line of research in manipulation should be to understand the integration of sensory motor information to build an internal model of the object and the effector system to support such anticipation.
User Interaction With CAD Models With Nonholonomic Parametric Surface Constraints
Authors: Nelson Donald D. , Cohen Elaine
Published: January 2022

User manipulation of assembly models can provide insight during the early, formulative design stages into kinematic and dynamic characteristics of a mechanism. We present the advantages of kinematic representation of constraint equations in fully Cartesian coordinates, a departure from standard practice for interactive mechanical assembly at interactive rates.

Formulations of a surface rolling contact constraint equation and its Jacobian, defined as a joint between two NURBS surfaces via position, tangency and velocity constraint relations, are derived for use in dynamic simulation and assembly optimization. The constraint equation formulations use quaternions to represent orientation. An appendix develops appropriate differential algebra.

In this work we develop the use of constraints in global frame Cartesian coordinates for describing operator-in-the-loop interactions with mechanical assemblies under a unified framework combining lower-pair joints and more general surface contact interactions.
Using a Wavelet Network to Characterize Real Environments for Haptic Display
Authors: Miller Brian E. , Colgate J. Edward
Published: January 2022

This paper will introduce a framework for characterizing real environments, using recorded force/displacement data, for use in haptic display. Steps in the framework include data acquisition, identification, model verification, and implementation. Identification and implementation will be developed in detail. After obtaining a conceptual understanding of the roles data acquisition and model verification play in the process, the methods used in this paper will be described. To meet the requirement for the identification stage, a proven technique in nonlinear system identification will be adopted. This technique, called wavelet network, will provide a tool that is capable of identifying environments with significant nonlinear features. A theoretical development along with experimental results will be presented using a spring attached to a wall. This environment exhibits a linear region with a single nonlinearity. The wavelet network was chosen because it was designed specifically for use with problems of high input dimension. Therefore, it is the expectation that the procedure will be useful in identifying environments of varying complexity. Currently, the technique can be used to identify static nonlinear environments. Work is being done to extend its capabilities to handle dynamic environments.
Do Humans Sense Finger Deformation or Distributed Pressure to Detect Lumps in Soft Tissue?
Authors: Peine William J. , Howe Robert D.
Published: January 2022

Detecting and localizing hard lumps in soft tissues is an important medical procedure. A psychophysics experiment measured minimum indentation forces required to detect a hard ball embedded in a soft rubber model. Ball size and finger indentation speed were varied. Threshold detection forces increased with ball size and decreased with indentation speed. The shape of the finger and contact pressure distribution on the finger were measured at the threshold force. The relative deformation of the finger induced by the ball was determined by comparing the shape of the finger indenting models with and without a ball at the same indentation force. The maximum relative deformation was nearly constant for the different ball sizes and increased significantly as indentation speed decreased. The measured pressure distributions show a considerable change across different ball sizes and indentation speeds. This suggests subjects sensed deformation of the fingerpad induced by the ball and not changes in the pressure distribution.
Control of Linear Systems Under Actuator Saturation
Authors: Jayasuriya Suhada
Published: January 2022

Presented in this paper are some preliminary ideas on the role of actuator saturation in linear systems that are under study. Real actuators have limited bandwidth and they saturate upon receipt of overly large inputs. Such actuator saturation can have catastrophic consequences especially in feedback control of open-loop unstable plants. It is well known that even when used with stable plants, actuator saturation can lead to undesirable limit cycle behavior. Actuator saturation can also easily occur when integrations are used within a control loop. Integrator anti-windup schemes have been proposed for overcoming that situation. One obvious but almost unresearched idea for eliminating wind up would be to get rid of the need to use integral action inside the feedback loop. So the crucial question is whether or not it is possible to get good steady state accuracy without using integral control? One idea could be to delegate the tracking responsibility to a carefully designed pre-filter.
A Power Flow Model for High Speed Motorized Spindles: Heat Generation Characterization
Authors: Bossmanns Bernd , Tu Jay F.
Published: January 2022

Lack of a more complete understanding of the system characteristics, particularly thermal effects, severely limits the reliability of high speed spindles to support manufacturing. High speed spindles are notorious for their sudden catastrophic failures at high speeds due to thermal problems without alarming signs. In this paper, a complete power flow model is developed to characterize the power distribution of a high speed motorized spindle, in particular the characterization of the heat generation within the spindle by the built-in motor and the bearings under the influence of speed, preload, and lubrication. The model is verified with a custom-built high performance motorized spindle of 32 KW and maximum speed of 25000 rpm (1.5 million DN) using several systematic test procedures. The results reveal interesting observations of spindle beat generation due to the built-in motor and the bearings.
Compensation of Thermal Errors in Machine Tools With a Minimum Number of Temperature Probes Based on Neural Networks
Authors: Weck Manfred , Herbst Uwe
Published: January 2022

Besides the low static stiffness of the machine structure and tool wear, thermal deformations are a major reason for dimensional and geometric work piece errors. As an alternative to cooling, insulation and other design measures, an indirect control compensation offers an inexpensive possibility to reduce thermally caused displacements which occur at the cutting point. The thermo-clastic displacements are calculated from the temperatures of different structure points and are corrected via the NC. In order to reduce the implementation expenditure and to achieve a good transformation capability for other thermal loads, it is necessary to only consider the displacement-relevant temperature measurement points. Finding out the relevant temperatures used to be a difficult and time consuming process. This paper presents a procedure based on a dynamic neural net that automatically determines relevant temperature probes. The quality of neural models and their ambility to generalise depends strongly on the net size, but this parameter is difficult to define in advance. Apart from the calculation of the correction parameters, the developed neural net also modifies its size during the learning phase. After the introduction of this model, compensation results for a milling machine are shown and compared to classical linear equation models.
Detection of Machine Tool Chatter During High Speed Milling
Authors: Skolnick Robert B. , Keltie Richard F.
Published: January 2022

Issues related to modeling, detecting and controlling machine tool chatter were investigated during high speed milling of aluminum. The growth rate of chatter was measured to determine the time allowed to detect and compensate for chatter. It was found that, depending on the cutting parameters, chatter became fully developed within five to ten rotations of the spindle. During the onset of chatter it was observed that several additional frequencies occurred in the frequency spectrum of the workpiece acceleration. To identify the cause of these additional frequencies a simulation of the forces generated during unstable helical milling was developed. The simulation assumed that the dynamic displacement of the end mill was in a fixed radial direction relative to the end mill. The simulation showed that the combined effect of this radial vibration and tool runout caused excitation at these additional frequencies.
Structural Analysis of a Sensor Module for the “Smart” Bearing
Authors: Gao Robert , Sahay Priyaranjan
Published: January 2022

The dynamic behavior of a miniaturized sensor module that is structurally integrated into the raceway of a ball bearing was studied. Modal analysis was conducted to identify critical bearing operational speeds and their effects on the electronic components of the module. Forced vibrations of the module under various loading conditions were studied to quantify deflection and stress within the module. The study provides insight and guidance to the design, configuration, and packaging of the module before its realization using an IC foundry.
Three-Dimensional Stress Analysis of the Chains in Tracked Vehicles
Authors: Campanelli M. , Shabana A. A. , Choi J. H.
Published: January 2022

In this investigation, the dynamic stresses of the chains of three-dimensional tracked vehicles are examined. The numerical procedure developed in this investigation integrates classical constrained multibody dynamics methods with finite element capabilities. The nonlinear equations of motion of the three-dimensional tracked vehicle model in which the track links are considered flexible bodies, are obtained using the floating frame of reference formulation. Contact force models are used to describe the interaction of the track links with the vehicle components and the ground. A detailed three-dimensional finite element model is developed for the track link. The finite element model is first utilized to predict the natural frequencies and mode shapes of the track link. The natural frequencies obtained numerically by using the finite element method are verified experimentally by using a modal identification technique. A partially linearized set of dynamic equations is developed based on the floating frame of reference formulation to study the motion of the flexible links and to predict their forces. The results of the dynamic stress analysis of the track links are presented, and the differences between these results and the results obtained by using the static stress analysis are demonstrated.
Driver Assisted Control Strategies: Theory and Experiment
Authors: DePoorter Mark , Brennan Sean , Alleyne Andrew
Published: January 2022

This work investigates the use of feedback controller augmentation of driver inputs to achieve a desired vehicle performance. The vehicle performance is specified as a Reference Model. The driver maintains nominal control of the vehicle by direct actuation of the front steering inputs. The controller then determines the appropriate rear steer inputs necessary for tracking the reference model. As a consequence the driver is able to specify, within limits, the type of handling behavior required of the vehicle. A strategy based on yaw rate control is presented. An appropriate vehicle model is developed and a polynomial pole placement technique is used to control the vehicle. To account for vehicle model changes due to variations in forward velocity, a continuous time Recursive Least Squares approach is examined for on-line identification and adaptive control. The strategy and control designs are implemented experimentally on the Illinois Roadway Simulator (IRS), a scale vehicle testbed for vehicle dynamics and controls. Results and limitations are discussed.
Analysis and Controller Design Based on Linear Model for Heavy-Duty Vehicles
Authors: Wang Jeng-Yu , Tomizuka Masayoshi
Published: January 2022

In this paper, we present the time domain, frequency domain and pole/zero analyses of a linearized model of heavy-duty vehicles (tractor-semitrailer type) for lateral control. These analyses are conducted to examine the steering response subject to variations of speed, road adhesion coefficient and look-ahead distance for the lateral position sensor. Based on these analyses, a linear controller for lane following is designed. The close-loop simulation is conducted to show the effectiveness of the linear controller.
System Availability and Inspection Intervals
Authors: Margulies Tim
Published: January 2022

The purpose of this paper is to investigate the availability of a system that undergoes Weibull probability failures. The inspection and repair process consists of periodic inspections. Illustrative calculations are presented.
TRAKVU: A New Tool for Modeling Track Irregularities in NUCARS
Authors: Ahmadian Mehdi , Kramp Kenneth P. , Dembosky Mark A.
Published: January 2022

The accuracy of the results from a rail vehicle dynamic model is dependent on the realism of the track input to the model. An important part of the track input is the irregularities that exist on actual track. This study presents a new modeling tool, called TRAKVU, for creating track data with the irregularities for use as the input to NUCARS, a rail vehicle dynamic analysis tool. TRAKVU enables users to create track data and apply the appropriate irregularities so that the track will have the same characteristics as the desired class of track.

A validation was performed to determine how well track created in TRAKVU simulated actual tracks. The statistical characteristics of created tracks were compared directly with actual tracks. The created track was also used as input to a dynamic model. The predicted vehicle response was then compared with the vehicle response due to measured track data. The results from the validation showed that the created track performed as well as the measured track in providing the input to a dynamic model.
Electro-Motive’s DE30AC Passenger Locomotive: A Systems Approach to Locomotive Configuration
Authors: Goding David J.
Published: January 2022

Electro-Motive Division (EMD) of General Motors Corporation has designed the first two models in a series of new passenger locomotives for the North American market. Incorporating many new ideas and concepts through use of a systems approach to the locomotive configuration, these new models offer a significant advancement of the state-of-the-art for passenger locomotives. Among the features of the DE30AC locomotive family are: capability for up to 4,500 brake horsepower, stainless steel sidewalls on a monocoque carbody including integral fuel tank and improved collision strength; isolated engine-generator for low cab and wayside noise and reduced locomotive vibration; modularized equipment in centralized locations; AC traction and head end power (HEP) system; locomotive auxiliary electrical equipment powered from the HEP system; an optimized electrical equipment ventilation system; and a unique, opening front end to facilitate maintenance. This paper describes the locomotive and some of the design considerations in developing this model, with emphasis on the rationale used to select the production configuration.
Prediction of Metal Matrix Composite Response to Multiaxial Stresses
Authors: Ahmad Jalees , Newaz Golam M. , Nicholas Theodore
Published: January 2022

A theory is presented which can be used in stress analysis of metal matrix composite in the inelastic range and under multiaxial stress states. Theoretical predictions of composite deformation and damage under various stress states have been experimentally validated. The theory has been incorporated in a finite element analysis framework so that practical design problems can be addressed.
Time-Dependent Degradation in Fiber Composites due to Multiple Constituent Degradation Mechanisms
Authors: Iyengar N. , Case S. W. , Halverson H. G. , Curtin W. A.
Published: January 2022

The failure of fiber reinforced composites at elevated temperatures can occur due to time-dependent degradation mechanisms of the constituent fibers, matrix, and/or interface. Here, analytic models are presented for predicting deformation and lifetime due to two important mechanisms of degradation when acting simultaneously. The mechanisms are matrix/interface creep and fiber degradation by slow crack growth within the fibers. Both mechanisms are non-linearly dependent on the state of stress in the material and so, when acting simultaneously over comparable time-scales, the damage rate is strongly accelerated due to the non-linear coupling of the mechanisms. The resulting composite lifetime can me much smaller than the life under conditions when only a single degradation mechanism is acting, even when the time scales of the two mechanisms differ by large amounts. For example, if when acting alone fiber degradation causes failure in time tf and creep causes failure in a time 100tf, when acting together the failure time can be 0.1tf or smaller at stresses on the order of 1/2 the ultimate fast-fracture strength. The remaining strength under single and combined degradation modes is also studied within these analytic models. Then, several “kinetic” laws for predicting the remaining strength versus time due to multiple degradation mechanisms, including the MRLife approach, are studied. Specifically, the individual remaining strengths for each degradation mode as found from the micro-mechanical models are used as input into the kinetic laws, and the predicted lifetimes are then compared to those from the micro-mechanical models to assess the accuracy of the kinetic laws.
Life Prediction of Metal Matrix Composites: A Comparison of Different Matrix Constitutive Relations
Authors: Ahmad Jalees , Santhosh Unnikrishnan
Published: January 2022

Global deformation response of metal matrix composites (MMCs) to applied mechanical and thermally induced stresses depends upon (a) the mechanical and thermal properties of the constituent materials, (b) residual stresses in the constituents induced by the composite consolidation process, and (c) the nature and extent of micromechanical damage which may occur and accumulate over time. In the present work, a mechanistic model for predicting time dependent global deformation response of unidirectional metal matrix composite subjected to fiber direction stresses is used in conjunction with several viscoplastic models for the matrix, viz. power law, Bodner-Partom and GVIPS, and compared with laboratory test data. The model incorporates the effect of the micromechanical residual stresses in the fibers and the matrix induced by the composite fabrication process. The model also incorporates the effect of discrete existing and/or progressively occurring fiber damage on global MMC deformation response. The criterion for fiber fractures is based on statistical information on fiber strength. Comparisons of the results from this model with results from detailed finite element analyses and with laboratory test data shows that the simple model provides reasonably accurate predictions.
Recent Studies of Sound Transmission Loss of Sandwich Aircraft Structures
Authors: Thamburaj Priya , Sun J. Q.
Published: January 2022

This paper presents a summary of recent studies of sound transmission loss of sandwich aircraft structures for global transportation applications. A review of the literature on the related research is given. Some research issues are identified that are important to reducing interior noise of aircraft for global transportation applications. Recent results of vibration and sound transmission loss are presented for a sandwich beam with anisotropic skin and core materials. The study has found a significant increase of the transmission loss for the sandwich beam with anisotropic materials as compared with isotropic ones.
Thin, Low Frequency, High Displacement Actuator Panels
Authors: Tressler James F. , Howarth Thomas R.
Published: January 2022

An advanced type of thin, high displacement, low frequency actuator panel is being developed for in-air active vibration control applications. The actuator panel consists of sixteen 25.4 mm diameter cymbal-type flextensional elements placed mechanically and electrically in parallel with each other between two stiff 10 cm by 10 cm stainless steel cover plates. The total thickness of the actuator panel is 6.35 mm. Electrical admittance measurements show a free-free fundamental resonance frequency of 645 Hz. Laser Doppler velocimetry (LDV) measurements show a clamped-free resonance frequency of 444 Hz with displacements on the order of 1 μm when driving the panel at one Volt at its resonance frequency.
Adaptive Vibration Isolation for Flexible Structures
Authors: Ertur David , Li Yugang , Rahn Christopher D.
Published: January 2022

Vibration isolation control for flexible structures restricts the response resulting from external disturbances to areas not requiring high precision positioning and/or pointing. This paper introduces adaptive feedback isolation controllers, based on Lyapunov theory, that regulate and allow tracking of the undisturbed (controlled) coordinates in a flexible structure. Under assumptions of inertially decoupled controlled and uncontrolled coordinates, symmetric and positive definite mass matrix for the controlled subsystem, asymptotically stable eigenvalues for the uncontrolled subsystem, and bounded disturbances, an adaptive regulator asymptotically drives the controlled coordinates to zero. Under similar assumptions, an adaptive tracking algorithm drives the controlled coordinates to desired time trajectories. Experimental results on a three mass system compare the response of the adaptive isolation controllers with standard PID control. The adaptive regulator provides faster transient decay than PID control using the same control effort. The adaptive tracking controller has the same tracking error of PID using 30% less control effort.
Tuning of Distributed Fuzzy Logic Controller for a Flexible-Link Robot
Authors: Trabia Mohamed B.
Published: January 2022

Fuzzy control has emerged as a practical alternative to conventional controllers due to its computational efficiency and robustness. It has been already implemented successfully in many applications. Several questions, concerning fuzzy control, remain however unanswered. For example, design of fuzzy controllers usually depends on intuition and experience, which may work well only if there is a sufficient level of familiarity with the system and if plant parameters remain fixed. Fuzzy controller for flexible robots does not fit well within this category. While the rules for such controllers may be intuitive, selecting the ranges of the membership functions for the robot’s input and output variables can be challenging. Wrong choices may lead to sluggish response, excessive vibration, or instability. In this paper, a dynamic model for a single-link flexible robot using finite element method is presented. Distributed Fuzzy logic controllers are used to control angle and link vibrations of this robot. A computationally efficient approach for tuning these functions to improve its performance is proposed.
Precision Piezoelectric Micro-Positioner for Line Boring Bar Tool Insert
Authors: O’Neal George P. , Min Byung-Kwon , Li Chen-Jung , Pasek Zbigniew J. , Koren Yoram , Szuba Phil
Published: January 2022

The paper describes an effort to develop a prototype smart boring tool supporting agility at the station level by enabling automated tool change and providing an advanced on-line compensation mechanism. The tool utilizes a compensation mechanism powered by a piezoelectric microactuator driven by an advanced controller, compensating for the position error of the boring bar and effectively rejecting cutting force disturbances. Experimental data were used to verify the theoretical and simulation results indicating successful operation of the tool with the bandwidth of up to 500 Hz, providing the tool tip compensation range of 40 μm with a resolution of 0.2 μm.
Bending/Torsion Control of Wing Panels With Diagonal X-Actuators
Authors: Ye R. , Tzou H. S.
Published: January 2022

Simultaneous bending and torsion control of aircraft wings or helicopter blades can enhance the aerodynamic efficiency and flight maneuverability of aircraft and helicopters. Bending control of plates using parallel segmented piezoelectric actuators was demonstrated in the past. In this paper, a new X-actuator configuration of piezoelectric patches based on the same total actuator area is used to control both bending and torsion vibrations simultaneously. Control effectiveness of the X-actuator configuration is studied and compared with that of the original parallel line-actuator configuration. Finite element analysis data suggest that the new X-actuator configuration is effective to control of both bending and torsion modes.
Passive Voice Coil Feedback Control of Closed-Box Subwoofer Systems
Authors: Chen Cheng-Yi , Chiu George T.-C. , Peng Huei , Cheng Chi-Cheng
Published: January 2022

In this paper, the feasibility of using voice coil back-emf signal as feedback information for closed loop control was investigated. A dual voice coil closed-box subwoofer system is use to demonstrate the effectiveness of back-emf feedback control. A second order filter is developed to extract the velocity information from the coil back-emf signal. A PD controller is well suited for reducing the harmonic distortion and extending the subwoofer bass response. Experimental results verified that the proposed control scheme effectively extended the bass response of the subwoofer system by one octave and at the same time reduced harmonic distortion by more than 6 dB. The proposed feedback and control scheme can be easily implemented using inexpensive analog components, which can further reduce the cost and complexity of the system.
Passive Vibration Suppression of Beams Using Magnetomechanical Coating
Authors: Yen H.-Y. , Shen M.-H. Herman
Published: January 2022

This paper investigates the possibility of using magnetomechanical coating for enhancing high damping capacity on the high frequency structural response of beams. An analytical procedure is developed for modeling the dynamic behavior of beams coated with a plasma sprayed iron-chromium based coating. The effect of hysteresis nonlinear damping properties in terms of various stress or strain levels is investigated in the study. For the practical applications, in accordance with the proposed analytical procedure, a vibration formulation is presented. An extension to a continuous system is also discussed in this research.
Experimental Comparison of Delayed Resonator and PD Controlled Vibration Absorbers Using Electromagnetic Actuators
Authors: Elmali Hakan , Renzulli Mark , Olgac Nejat
Published: January 2022

The Delayed Resonator (DR) is a recent active vibration absorption technique which uses time delayed position feedback to generate ideal resonance in a passive vibration absorber. This can also be achieved using proportional and feedback (PD) control. In this paper, these two techniques are compared analytically and experimentally. It is also shown that actuator dynamics must be considered in order to determine the control parameters correctly. A theoretical development is presented towards this purpose. Experimental results show that both techniques are equally effective in vibration absorption.
On the Life Prediction and Accelerated Testing of Solder Joints
Authors: Qian Zhengfang , Liu Sheng
Published: January 2022

A critical review of the life prediction and accelerated testing of solder joints, including the role of constitutive modeling and the factors of accelerated testing, is presented in this paper. As a perfect example, Ford solder joint specimen was used to investigate accelerated testing factors under various accelerated testing conditions in terms of thermal fatigue life. Moreover, a typical PQFP (Plastic Quad Flat Pack) package was chosen to clarify the significance of fatigue life prediction in terms of different finite element models and unified and separated constitutive models. Thermal fatigue life prediction of flip chip packages with ball pitch sizes from 250 micron to 50 micron has been performed to illustrate underfill strengthening mechanisms and obtain an upper bound of accelerated testing factors, which can reduce testing time from three years to one week. Rate/temperature-dependent nonlinear properties of both eutectic solder and underfill FP4526 have been embedded in the ABAQUS finite element analysis for flip chip packages. All those examples enlighten key points addressed in this report.
A Linear Motor Driven Mini Tester and its Application to Thermal/Mechanical Fatigue Testing of Solder Joint Specimen
Authors: Lu Minfu , Qian Zhengfang , Liu Sheng , Wu Jianhau
Published: January 2022

A linear motor-driven mini fatigue tester has been developed at Wayne State University and reported in this paper with its application to mechanical fatigue testing of mini solder joint specimen. The tester, as the second generation of our DC motor-driven mini tester, is backlash free. Another advantage of the tester is its capability of high speed and long travel distance, making it powerful to the wide range of frequencies for mechanical fatigue testing, which is ideally suitable for accelerated fatigue testing. Several fatigue tests of solder joints have been performed by this mini fatigue tester. It is found that the kinematical hardening coexists with cyclic softening of solder joints, indicating early damage stage of solder fatigue. The testing results of a solder joint specimen designed by authors can also indicate both macro crack initiation and its propagation The voiding on failure surface of a solder ball specimen after fatigue is observed to support ductile damage characterization of solder joints.
Study of Nucleation of Diamond on Silicon Substrate by Ab-Initio Molecular Dynamics
Authors: Kayaba Tomoo , Inoue Akinori , Saka Masumi , Abé Hiroyuki
Published: January 2022

The diamond film has been drawn attention for the electronic devices used in higher temperature or the coating of cutting bytes used for the super hard aluminum because high quality diamond film has recently been able to be synthesized cheaply from the gas phase, using the CVD (Chemical Vapor Deposition) method. Diamond thin film has been confirmed to be connected to the substrate at the place around the nuclei grown at the beginning of deposition. In this paper, in order to solve fundamental process of the nucleation of the diamond based on quantum mechanics, ab-initio molecular dynamics simulation of the nucleation of the diamond on the silicon substrate is conducted. Only one carbon atom is used for the simulation aiming to show the fundamental process of the nucleation. A model that consists of a silicon substrate and a carbon atom is provided. The Car-Parrinello method is used for ab-initio molecular dynamics calculation. The action of the carbon atom on and in the silicon substrate in the simulation, and the situation of the combination between the silicon atoms in the substrate and the carbon atom are shown.
Wall Effects in Multiparticle Settling
Authors: Zhu Qinsheng , Clark Peter E.
Published: January 2022

Since many industrial processes involving suspended particles settling near walls, understanding the process is important. There has been a lot of work done on particle behavior near walls in Newtonian fluids, but not much has been reported for particles settling near walls in non-Newtonian fluids. There is almost no data available for multiparticle systems in either Newtonian or non-Newtonian fluids. In this study, we report the settling of single particle and two-particle systems at or near convex, concave and flat walls in both Newtonian and non-Newtonian fluids.
Spatial Concentration Variation in a Suspension Flow Through a Mold Cavity
Authors: Olivero Kristian A. , Altan M. Cengiz
Published: January 2022

The time dependent orientation field in a steady, Newtonian, Hele-Shaw flow containing slender particles is experimentally observed. The flow is created by injecting a suspension of corn syrup diluted with water containing fibers into a planar mold cavity with a three to one sudden contraction downstream. Time dependent orientation data is collected in the vicinity of the sudden contraction with a digital CCD camera connected to a PC based video capture card. Computerized image analysis is performed on each image to obtain the planar orientation of each fiber and the fiber concentration in that region of interest. Radial orientation distribution histograms are generated for different regions and time intervals to investigate time dependency of the orientation field and fiber volume fraction. Although the flow is steady, fiber concentration is found to fluctuate over time. Fiber concentration also varies considerably from region to region, with some regions containing fiber volume fractions much lower than the average volume fraction of the injected suspension.
Modelling and Control of a High Speed Hydrostatic Transmission
Authors: Njabeleke Ignatius A. , Pannett Richard F. , Chawdhry Pravir K. , Burrows Cliff R.
Published: January 2022

Fluid power systems are highly nonlinear, making the application of traditional linear feedback control techniques challenging. H∞ robust control techniques have been extensively studied recently but their practical feasibility in fluid power systems has not been convincingly demonstrated. In this paper, we consider the modelling and application of H∞ robust control to a hydrostatic transmission. We propose a dual mode controller which is extremely effective, delivering robust stability over the entire speed range and offering bumpless transfer, windup protection and multirate sampling at no extra cost, a factor which is crucial in digital implementation. The particular H∞ approach used is McFarlane and Glover’s loop shaping which, in addition to simplicity, admits a wider class of uncertainties than comparable schemes. We show that despite some challenges, H∞ loop shaping is able to satisfy a variety of control objectives and a successful application need not be of high order.
Implementation of Rosenbrock Integration Algorithm With Adaptive Step Size Control in Time-Domain Simulation of Fluid Power Systems
Authors: Käppi T. J. , Ellman A. U. , Piché R.
Published: January 2022

Numerical simulation models of fluid power systems typically have a large scale of different time constants and so can be considered as numerically stiff systems.

The Rosenbrock method is a differential equation integration algorithm with suitable accuracy and stability properties. In this paper the implementation of the Rosenbrock method as part of a time-domain fluid power system simulation package is presented.

Adaptive time step size control makes it possible to achieve an optimal computational effort with controllable integration error based on user-defined error tolerance.

Computation of examples show considerable improvement in accuracy and computational speed over the previously used integration method.
Design of Objective Functions for Optimization of Multi-Domain Systems
Authors: Andersson Johan , Pohl Jochen , Krus Petter
Published: January 2022

Engineering problems are often characterized by many conflicting objectives which span over several engineering domains. In this paper an approach to design of objective functions for engineering problems is presented.

Multi-domain systems can be characterized as complex systems which combine different fields of engineering. Here an aircraft landing gear is studied which is a true example of a multi-domain simulation problem due to the presence of mechanical, electrical and hydraulic sub systems. On this simulation model a non-gradient optimization strategy is applied where the formulation of the objective function is supported by the House of Quality method. The design of an objective function for optimization is in many cases a complex procedure involving a great amount of expertise. The House of Quality method is used here both to facilitate team activities and to elucidate the relation between system characteristics and system parameters.
Flow Analysis and Modeling of Shock Absorbers
Authors: Herr F. , Mallin T. , Lane J. , Roth S.
Published: January 2022

A Computational Fluid Dynamics (CFD) method, combined with a dynamic modeling technique were introduced to study the flow and performance of automotive hydraulic damper / shock absorbers. The flow characteristics of component obtained by using CFD was applied to dynamic modeling package to predict the damping force. The component CFD analysis showed unique features as far as flow part tern, discharge coefficients and pressure distribution for various shock absorber components. Dynamic damper model was constructed by using a commercial package Easy5 with flow information provided by CFD. A simple representation of the complicated design of shocks as a network of fixed and variable restrictions in series and parallel connected by compliant volumes of oil is suitable for capturing the dynamics important to vehicle handling simulations.
Leakage Behaviour of Four-Way Servovalve
Authors: Ellman Asko
Published: January 2022

The paper presents a model for a four-way servovalve which is based on nonlinear modelling of valves’ leakage behaviour. The model is identified according to measured flow rate at valve ports and pressure gain curve. The model can take into account some unsymmetry of the valve.

The model is verified in the case of a commercial servovalve.
Slipper Tipping Within an Axial-Piston Swash-Plate Type Hydrostatic Pump
Authors: Manring N. D.
Published: January 2022

In this paper, the dynamic characteristics of the slipper are investigated analytically for the purposes of predicting the phenomenon of slipper tipping without the use of laboratory techniques. In particular it is shown that slipper tipping result from the reciprocating inertia of the piston / slipper assembly as well as the centrifugal inertia of the slipper itself. Based upon a slipper tipping criterion, it is further shown that the worst tipping conditions occur at top dead center when the piston is moving from the discharge port to the intake port of the pump. In this region a combination of a pressure force and a force from the hold-down device may be used to guarantee successful operation of the pump. The required magnitude of these forces is shown in a closed form as a function of operating conditions which provides the design engineer with useful guidance for optimizing the overall design of the slipper and its hold-down device.
Vibration-Assisted Coupled Transport-Reaction Processing of Advanced Materials
Authors: Ilegbusi Olusegun J.
Published: January 2022

This paper describes a numerical study of the effect of vibration on two materials processes characterized by coupled transport-reaction phenomena. The first process is the production of SiC by the infiltration of porous carbon preform with molten silicon or silicon alloy, and subsequent chemical reaction between Si and C. The second process involves the burnout of organic binders from ceramic greenware. Transport equations are solved by the finite-domain numerical scheme for the conservation of mass, momentum, energy and species concentration in the porous media. A simple harmonic vibration is imposed as a transient source on the momentum equations. The growth rate of SiC and pressure rise in the ceramic greenware are predicted. The results demonstrate the potential of vibration to improve both materials processes. It is suggested that further systematic studies may allow the signatures of vibration to be used for characterization of the final products.
A New Analysis of Elastic Wave Resonance Scattering From an Elastic Cylinder
Authors: Rhee Huinam
Published: January 2022

The problem of elastic wave resonance scattering from elastic targets is discussed in this paper. A new resonance formalism to extract the elastic resonance information of the target from scattered elastic waves is introduced. The new resonance formalism is an extension of the works developed for acoustic wave scattering problems by the author. The classical resonance scattering theory (RST), which is usually being used for this type of problem, computes reasonable magnitude information of the resonances in each partial wave, but the phase behaves in somewhat irregular way, therefore, is not clearly explainable. The new method has been developed to obtain physically meaningful magnitude and phase of the resonances. As an example problem, elastic wave scattering from an infinitely-long elastic cylinder was analyzed by the proposed new method and compared with the previous studies by RST. In case of no mode conversion, both methods generate identical magnitude. However, the new method computes exact π radian phase shifts through resonances and anti-resonances while RST produces physically unexplainable phases. In case of mode conversion, even magnitudes are slightly different. The phase shifts through resonances and antiresonances obtained by the new method are not exactly π radians due to energy leak by mode conversion. But. the phases by the new method still show more reasonable and intuitive behavior than those by RST.
A Discrete Model of Turbulence Loading Function for Computation of Flow-Induced Vibration and Noise
Authors: Hwang Y. F.
Published: January 2022

This paper discusses a discrete representation of the spatially homogeneous and temporally stationary turbulence loading on a structure induced by low speed incompressible flow. In the classical random vibration theory involved with continuous structural systems, this forcing function is expressed as the space-time cross correlation function or its Fourier conjugate, the wavevector-frequency spectrum of the turbulent boundary layer (TBL) wall pressure. These functions cannot be applied directly to finite discrete systems, such as most finite-element structural models, because they contain a fine-scale oscillating component which represents the predominant pressure fluctuations convected with the flow. For example, at mid- and moderate high frequencies, this fluctuating length scale may become smaller than the mesh size of a discrete structure model. An approximated discrete forcing function model to ease this numerical difficulty is presented in this paper. The approximate forcing function model is verified by comparing the numerically calculated modal input force spectra to that obtained from exact analytical solutions. The numerical calculated values approach the exact solutions as the finite-element mesh size becomes smaller.
Marine Outboard Engine Exhaust System Design
Authors: Church Nathan J.
Published: January 2022

This paper describes a project in which the objective was to reduce the underwater sound levels produced by marine outboard engines while simultaneously maintaining acceptable above-water sound levels. The exhaust systems of different marine propulsion systems were studied, with emphasis placed on those of two-cycle outboard engines.

The acoustic performance of a typical 140 horsepower (104 kW) two-cycle outboard engine was measured and recorded. Modifications were then made to the engine’s exhaust system in an attempt to reduce the engine’s operational underwater sound levels. These modifications are discussed in detail. With the modifications complete, the engine’s acoustic performance was re-examined.

The modifications to the outboard’s exhaust system were found to reduce the engine’s overall underwater sound pressure levels by 77% at 1000 rpm. Above-water sound levels were found to be slightly increased at low engine speeds and decreased at high engine speeds.
Development and Evaluation of a Surface Acoustic Intensity Probe
Authors: Driesch Patricia L. , Koopmann Gary H.
Published: January 2022

The subject of this paper is the development of a new surface acoustic intensity probe that measures the sound power radiated by vibrating structures. Surface intensity methods have been a research subject for over two decades and provide a foundation for the probe design. The design combines two inexpensive components, an accelerometer and a microphone, both requiring careful calibration. A calibration device and method were developed to measure the frequency-dependent sensitivity of the microphone over a 160 to 1600 Hz frequency range. The calibrator mounts the probe on top of a piezoelectric actuator and together they are enclosed in a small air cavity. This calibration method provides a frequency-dependent phase correction for the microphone. For a low frequency performance evaluation, an array of probes measure sound power radiated from a clamped plate to within a few dB of a two-microphone intensity probe.
A Modal Synthesis Approach for Dynamic Response of Space Vehicle Systems
Authors: Sarigul-Klijn Nesrin
Published: January 2022

Prediction of the modal properties of large-scale space vehicle systems as a whole is a complicated process. Therefore the idea of developing the dynamic behavior of a large system from its components or subsystems is usually favored. This paper presents an improved modal synthesis approach that uses Gradient Adaptive Transfinite Elements (GATE) Family of finite elements to satisfy the interface compatibility conditions between the sub-systems. Numerical examples including a simulation of a three-axis stabilized spacecraft are presented showing the improvements obtained by using the proposed approach.