bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multiobjective Optimization of a Leg Mechanism With Various Spring Configurations for Force Reduction
Authors: Shieh W. B. , Tsai L.-W. , Azarm S. , Tits A. L. 
Published: March 2021

Abstract
In this paper, the design of a two degree-of-freedom leg mechanism is accomplished by a two-stage optimization process. In the first stage, leg dimensions are optimized with respect to three design objectives: minimize (i) peak crank torque for an entire walking cycle, (ii) leg size, and (iii) vertical actuating force. Following the optimization of leg dimensions, in the second stage, spring elements with various placement configurations are considered for further reduction of the actuating force and crank torque. Several tradeoff solutions are obtained and a comparison between various spring configurations is made. It is shown that the inclusion of spring elements can significantly reduce the actuating force and crank torque.
Fatigue Strength of Metal / FRP Adhesive Joints Under Low Temperature
Authors: Hattori Toshio , Iwasa Masaaki 
Published: March 2021

Abstract
Fiber reinforced plastics (FRP) have the excellent thermal isolation characteristics, and are used for for cryogenic structures such as super conducting magnets. Generally these FRP materials are connected with metal structures using adhesive joint, as these FRP materials loose strength by the existence of bolt holes. In this metal/FRP adhesive joints high thermal residual stresses occur under cryogenic temperatures as the thermal expansion coefficients of both materials differ large. So, improvement of strength evaluation method of these bi-material adhesive joints under low temperature become indispensable to develop high-reliability super conducting magnet systems such as form Magnetic Levitation Liner Motor Car. In this paper we present a new fatigue strength evaluation method under high thermal residual stresses using following two stress singularity parameters K and λ at bonding edges.
τ ( r ) = K / rλ
Heat τ(r) is stress (MPa), r is the distance (mm) from the singular point (bonding edge), K is the intensity of stress singularity and λ is the order of stress singularity.
And this evaluation method is applied to Stainless-steel/Al2O3 FRP adhesive joint models.
A Virtual Engineering System for Electromechanical Products
Authors: Narikawa N. , Kuroiwa T. , Fujinuma T. , Sekimoto S. 
Published: March 2021

Abstract
This paper gives an overview of virtual enginecring (VE) system for electromechanical products. To reduce design costs and to manufacture high-quality products, it is well known that concurrent engineering (CE) is very efficient approach. Three-dimensional (3D) CAD system and engineering database system are essential components of CE. VE system is an environment to realize CE. By creating 3D models in a computer and performing some simulations such as mechanical, electronic, software simulation and integrated simulations, it is possible to estimate functions, assemblability, manufacturability and so on, without making prototype models. In this paper, we outline the VE system and mainly discuss the engineering database system which makes an important role of the VE system. This system is developed by applying the object oriented technology.
Introducing the Industrial Product Realization Process Into Mechanical Engineering Design Education
Authors: Browne Vance D. 
Published: March 2021

Abstract
The process by which new products are brought to market — the product realization process, or PRP — can be introduced in engineering design education.
In industry, the PRP has been evolving to concurrent engineering and product teams. The PRP includes components such as concept generation, analysis, manufacturing process development and customer interaction. Also, it involves the sequencing of the components and their connections which includes teamwork, project planning, meetings, reports and presentations.
A capstone senior engineering project, along with classroom lectures and presentations can be structured to provide knowledge and experience to the students in many of the PRP components and the connections. This paper will give an overview of the PRP and a project/lecture structure at the author’s university. The instructor recently joined the academic ranks after years in industry with responsibility for directing product development and R&D and for leading product development teams.
Elastic Robot Arms With Variable Length: Part II — Robust Control of Elastic Vibrations
Authors: Söffker Dirk 
Published: March 2021

Abstract
In the last years modeling, simulation, and control of flexibel structures have made an essential progress, especially stimulated by the requirements of space operations. For this working field, flexible lightweight robots can enhance the work space of space robots very well, if the length of the robot arm is variable.
Contributions in the corresponding literature mostly consider models of special configurations and perform simple approximations or even assume linear models to describe the elastic motions of the robot. However, especially in the case of lightweight robots undergoing large reference motion, its nonlinear dynamic behaviour should be modeled as exact as possible.
The mechanical system should be controlled to improve its dynamical behaviour. Unfortunately, it is not possible to measure the position of the endeffector. The only measurements that can be done are that of the strains of the beam. The control input should be the velocity (translational and rotational) transmitted to the base of the beam. This includes a correction of the actual path planning values as a kinematical control.
Here the specified task is solved in two parts:
Firstly, the variable length, the geometric nonlinear beam behaviour and the large reference motion of the driven joint are taken into consideration with a systematic modeling approach in (Söffker, 1995b; Söffker, 1995c).
Nonlinear control approaches can often be used only for special classes of problems assumptions have to be made, which cannot be generally fulfilled in practice. Here a new controller is developed which is realizable for on-line applications with the mentioned restrictions. Therefore, in a second part the mechanical plant will be controlled by a new observer-based dynamic compensation scheme.
Based on a linear time-invariant model, nonlinear effects and unmodeled dynamics are estimated in a first step by an Proportinal-Integral (PI) observer scheme, whereby the nonlinearities and the effects of the non-considered time-varying parameters etc. are assumed as external disturbances.
The used PI-observer (Söffker, 1995a) estimates the states of the system and the external disturbances under some weak assumptions.
Using this informations about the external disturbances to the nominal time-invariant system, the task of an extended regulator scheme is to compensate these effects in a second step. Because of the structure of the given mechanical system, usual static disturbance compensation schemes are not useful. Therefore a new dynamic approach is developed, which uses the estimations of the extended observer. The developed method does not depend on the structure of the physical problem and can be also used more generally. This is mainly due to the robustness of the observer-based dynamic compensation scheme.
Two examples of a very flexible spatial telescopic robot arm demonstrate the effects of disturbances compensation and control of the elastic vibrations induced by the initial conditions and the reference motion.
A New Aeroelastic Oscillator, Theory and Experiments
Authors: van der Burgh A. H. P. , Haaker T. I. , van Oudheusden B.-W. 
Published: March 2021

Abstract
This paper reviews recent work on the development of a new type of an aeroelastic oscillator with one degree of freedom in a uniform windfield. The typical characteristics of the oscillator are the low frequency (less than 1 Hz) allowing application of a quasi-steady modeling and a combined translational and rotational motion in cross-flow.
The oscillator is developed for the study of galloping oscillations in a wind tunnel. The model equation is validated by comparing its solutions with the experimental results. In the quasi-steady modeling for the dynamic behaviour use is made of the numerical values of aerodynamic coefficients obtained from wind tunnel measurements on the oscillator in a static position. Particularly the dependence of limit amplitudes on the flow velocity, obtained from the analysis of the model equations are compared with the ones obtained from experiments.
Numerical and Experimental Studies of the Vibration and Acoustic Behaviors of MRI Gradient Tube
Authors: Ling J. X. , Amor William , DeMeester Gordon 
Published: March 2021

Abstract
This paper comes from a realistic engineering project — an optimal design of the gradient system for a NMR machine for medical imaging. A three-dimensional finite element model was developed to study the vibration and acoustic characteristics of the gradient tube using ANSYS, a commercial Finite Element Analysis code. 3-D 8-node structural solid elements, 3-D 8-node layered structural elements and 3-D 8-node acoustic elements are used in the model. Linear transient analysis (dealing with the dynamic response of the composite cylindrical shell under periodic loading), as well as the coupling dynamic and acoustic analysis have been conducted. The linear transient analysis results in the displacement and acceleration time histories of the composite tube. The coupling analysis predicts the air motion (the sound wave) on the patient side of the tube. To verify the numerical results, some vibration and acoustic measurements are also carried out. All the numerical results are in good agreement with the experimental data and provide valuable information for evolving the gradient design. Similar FEA models have been developed for the alterative design versions. As a result, an optimal design of the gradient system has been achieved and the acoustic noise level of the latest design reduced by 12–15 dBA compared to the previous designs under similar operating conditions.
Wavelet Analysis of Stick-Slip in an Oscillator With Dry Friction
Authors: Liang J. W. , Feeny B. F. 
Published: March 2021

Abstract
The dynamic behavior of the transition between slipping and sticking motions of a mass-spring system with dry friction is studied numerically and experimentally. Three mathematical models of dry friction are incorporated in the forced oscillator’s equation of motion. The wavelet transform is used to analyze response signals for both high and low frequency contents. For the simulated dynamical response, the wavelet transform can efficiently depict the transition characteristics in the time/frequency domain. The signatures observed in wavelet contour plot are compared to experimental results to evaluate the mathematical friction models. The wavelet transform can also be used to detect the dynamics of the sensor. The low-frequency experimental friction behavior is somewhat like the Coulomb friction model and its smooth version.
Analysis of Beam-Like Structures With Displacement-Dependent Friction Forces: Part II — Multi-Degree-of-Freedom Model
Authors: Whiteman Wayne E. , Ferri Aldo A. 
Published: March 2021

Abstract
A multi-mode analysis of a beam-like structure undergoing transverse vibration and subjected to a displacement-dependent friction force is conducted. The level of displacement-dependence is governed by a ramp angle and spring arrangement as discussed in Part I. The system is studied by using harmonic balance as an approximate analytical solution and then by using a time integration method. The damping characteristics of the system are studied in detail. The results qualitatively agree with those obtained using a single-degree-of-freedom analysis of this system reported in Part I. Interesting findings include the appearance of internal resonance peaks when multiple modes are considered. Also, as with the earlier single-degree-of-freedom study, two dynamic response solutions exist at certain parameter values. It is found that the ability to control the amplitude of the response is a function of the frequency range considered. In general, near modal resonance peaks, the amplitude of the response decreases with increasing ramp angle. However, in an “overlapping” region between resonance peaks, the amplitude of the response actually increases with increasing ramp angle. Detailed analysis of the damping characteristics indicate that the dry friction damper is most effective in damping the fundamental mode. The other critical observation is that the damping contribution from the displacement-dependent dry friction damper is “viscous-like” in nature and relatively insensitive to the amplitude of the response. This result suggests that in the case of turbine or compressor blades, this type of damping arrangement may be effective in the suppression of flutter.
A Study of the Effects of Negative Friction-Speed Slope on Brake Squeal
Authors: Yuan Yongbin 
Published: March 2021

Abstract
Brake squeal is caused by friction-induced vibration of brake systems. It may take place due to several possible mechanisms. The inverse variation of friction coefficient with relative sliding speed, also called negative μ-v slope, is one of them. Although it has been demonstrated in many articles that negative μ-v slope can cause unstable vibration for systems with a single degree of freedom (d.o.f.), its effects on multi-d.o.f. brake systems are not yet well understood. Since almost all types of friction materials for automotive brakes exhibit negative μ-v slope under certain conditions, it is important to clarify its role in brake squeal.
The current study incorporates the negative μ-v slope friction law into a Finite element model for disc brake systems. The rotor and pads are modeled by beam elements, and the caliper is represented by a rigid body with two degrees of freedom. The effects of negative μ-v slope on the vibration stability of a brake system are studied along with several parameters including friction level, lining compression modulus, and steelback thickness.
Resonant-Frequency-Distribution of Internal Mass Inferred From Mechanical Impedance Matrices, With Application to Fuzzy Structure Theory
Authors: Pierce Allan D. 
Published: March 2021

Abstract
The partitioning of internal mass among bands of resonant frequencies is addressed for a prototype internal vibrating structure with small damping, attached via an arbitrary number NA of attachment points to an external structure. Insofar as the dynamics of the latter are concerned, the internal structure is adequately described by a frequency-dependent impedance matrix, any given column of which lists the ratios of the 3NA force components induced by one of the attachment points’ velocity components when all of the other velocity components are held to zero. The properties of matrix elements and their frequency dependence are discussed in relation to principles of mechanics, especially the requirements of translational and rotational invariance of the potential energy functions. Among the deductions are that modal masses can be defined with values calculable solely from the impedance matrix measurements, and that the modal masses sum to the total mass of the internal vibrating system.
Analysis of Pulsations and Vibrations in Fluid-Filled Pipe Systems
Authors: de Jong Christ A. F. 
Published: March 2021

Abstract
Pressure pulsations and mechanical vibrations in pipe systems may cause excessive noise and may even lead to damage of piping or machinery. In fluid-filled pipe systems pulsations and vibrations will be strongly coupled. A calculation method has been developed for the simulation of coupled pulsations and vibrations in pipe systems. The analytical method is based upon the transfer matrix method. It describes plane pressure waves in the fluid and extensional, bending and torsional waves in the pipe wall. Fluid pulsations and pipe wall vibrations are coupled at discontinuities (e.g. elbows and T-junctions) and via Poisson contraction of the pipe wall. For a given source description, the model calculates levels of vibration, mode shapes, vibro-acoustic energy flow, etc. The method has been validated experimentally on a test rig consisting of two straight pipes and an elbow. The predicted pulsation and vibration levels agree reasonably well with the measurements.
Optimal Unbalance Response of Continuous Rotors
Authors: Parszewski Zdzislaw A. , Li Dong-Xu 
Published: March 2021

Abstract
Dynamically optimal alignment of multi-bearing rotors has become one of the principal applications of the system dynamics in its configuration or layout parameters, (Parszewski, 1987). Using non-linear bearing effects and the independent parameters provided by their statical indeterminacy, the alignment of multi-bearing rotors has been optimised for least unbalance response. The rotor unbalance was estimated with the complex modal approach, using measured unbalance response. Some computed results and experiments on a four-bearing laboratory installation were presented in (Parszewski and Li, 1989). This present paper expands the analysis and provides an industrial application of the theory to a turbogenerator, operating in a power station. Comparison with the conventional catenary alignment is also given and shearing forces and bending moments on the couplings are revealed for both cases, showing the advantages of the optimal alignment of the rotor as a continuous shaft.
Forced Wave Propagation in Elastic Cables With Small Curvature
Authors: Behbahani-Nejad M. , Perkins N. C. 
Published: March 2021

Abstract
This study presents an investigation of the coupled longitudinal-transverse waves that propagate along an elastic cable. The coupling considered derives from the equilibrium curvature (sag) of the cable. A mathematical model is presented that describes the three-dimensional nonlinear response of a long elastic cable. An asymptotic form of this model is derived for the linear response of cables having small equilibrium curvature. Linear in-plane response is described by coupled longitudinal-transverse partial differential equations of motion, which are comprehensively evaluated herein. The spectral relation governing propagating waves is derived using transform methods. In the spectral relation, three qualitatively distinct frequency regimes exist that are separated by two cut-off frequencies. This relation is employed in deriving a Green’s function which is then used to construct solutions for in-plane response under arbitrarily distributed harmonic excitation. Analysis of forced response reveals the existence of two types of periodic waves which propagate through the cable, one characterizing extension-compressive deformations (rod-type) and the other characterizing transverse deformations (string-type). These waves may propagate or attenuate depending on wave frequency. The propagation and attenuation of both wave types are highlighted through solutions for an infinite cable subjected to a concentrated harmonic excitation source.
A Spectral Element for Acoustic Wave Propagation Through Multi-Layered Media
Authors: Doyle James F. , Bilodeau Brian A. 
Published: March 2021

Abstract
A spectral element is developed for analyzing acoustic wave propagation through multi-layered panels. The elements may be conveniently joined to model complex structures composed of many layers of solids and fluids. The element exactly models the in-plane responses over large domains. Results for the impact of single and double panel systems are presented.
Dynamic Stability Analysis for Multi-Flute End Milling
Authors: Shorr Michael J. , Liang Steven Y. 
Published: March 2021

Abstract
This research discusses the methodology of developing a symbolic closed form solution that describes the dynamic stability of multi-flute end milling. A solution of this nature facilitates machine tool design, machining parameter planning, process monitoring, diagnostics, and control. This study establishes a compliance feedback model that describes the dynamic behavior of regenerative chatter for multi-flute tool-work interaction. The model formulates the machining dynamics based upon the interconnecting relationship of the tool geometry convolution and the machining system compliance. The tool geometry convolution characterizes the cutting forces as a function of the process parameters and the material properties, while two independent vibratory modules, the mill tool and the workpiece, represent the machining system compliance. The compliance feedback model allows the development of a corresponding characteristic equation. By investigating the roots of the characteristic equation, this research symbolically expresses the stability of the system as a function of the cutting parameters, the tool geometry, the workpiece geometry, and the vibrational characteristics of the machine tool. Machining experimentation examining the fidelity of the regenerative charter model is discussed. The dynamic cutting forces, cutting vibration, and surface finish of the machining process confirm the validity of the analytical prediction.
Identification of Inertial Properties for Resiliently Supported Mechanical System
Authors: Nakamura Masanobu , Sawanobori Takeshi , Nagamatsu Akio 
Published: March 2021

Abstract
Parameters such as the principal moment of inertia, principal axis of inertia, and the location of center of mass are very important and necessary for simulation of the dynamic properties for design of a mechanical system (Kunieda, 1984, Taniguchi, 1976). Therefore in this paper, we examine an approach for experimental identification of the characteristic matrices using the modal parameters to obtain the inertia! properties of mechanical system. And then influences of the measurement error of Frequency Response Function (FRF) on identified values are investigated in detail.
Transient Response Analysis of Compressor-Piping Coupled System in Air Conditioning Units
Authors: Sawanobori Takeshi , Nakamura Masanobu , Nagamatsu Akio , Okamoto Jyoji 
Published: March 2021

Abstract
In the present paper authors wish to propose a method for the modeling and formulation to improve the design process of piping lines in the air conditioning unit. The essential part of the proposed method is to combine three identification principles : (1) the kinematical and kinetic analysis of compressor for obtaining the exciting forces and torque transmitted to piping lines; (2) the derivation method of physical matrices of piping lines with the finite elements method; (3) the experimental identification method of physical matrices of the compressor and accessories on resilient supporting elements using modal parameters obtained by modal testing.
The proposed method simplifies a procedure for formulation process of the compressor-piping coupled system and estimates accurately dynamic responses of piping lines. Validity of the proposed method is corroborated with experimental results.