bluuebunny/crossref_metadata_2025_split huggingface dataset:
Needle Fatigue Analysis for High-Speed Knitting Machines
Authors: Lyon Richard H. , Malinin Leonid M. 
Published: March 2021

Abstract
In modern, high capacity circular knitting machines, the small and fragile latch needles are often a performance-limiting machine element (Schuler, 1980). For these machines, the operating circumferential speed may exceed 1.5 m/sec. Due to the kinematics of the process, the cam driven needles are exposed to periodic excitation with frequency proportional to the speed. Increase in rotational speed gives rise to needle head fatigue breakages unless special design measures are undertaken. Frequencies up to 15 kHz have been observed and up to 60 kHz may be expected in the vibration spectrum. To understand what particular features of needle design may be responsible for their longevity, several techniques were developed to apply Finite Element Analysis software to estimating the fatigue life under a non-harmonic periodic loading.
The known FEA packages handle dynamics of a system with such loading as a general non-stationary problem, whereas much more efficient solution can be constructed by combining the analytical solution for a one DOF system under recurring impulses (5-functions of amplitude A) at the moments 0, T, 2T, …, and the natural modes of the system (with the driving point fixed) provided by FEA. As applied to the system in question, from the broad frequency range of the excitation forces and displacements, only frequencies close to those providing maxima to the transfer functions from the driving point to the head of the needle were selected. These frequencies are referred to further on as the response frequencies. Then the time history simulating polyharmonic stresses in the dangerous area was generated and processed according to the chosen fatigue criteria (a corrected linear hypothesis of damage summation, see below). Thus for any given node of the needle a point on the S-N diagram was obtained.
A wide spread desktop package, ALGOR, was selected as a Linear Stress Analysis solver. The described procedure is built on top of this package and allows design engineers to make judgements as to what design is more advantageous for needle longevity.
Dynamic Impact Upon Steel Target Plate: Experimental and Theoretical Analysis
Authors: Al-Obaid Y. F. 
Published: March 2021

Abstract
This paper gives complete analysis of the local failure of steel target plate subjected to shot impact by using three-dimensional dynamic finite element analyses in which provision is made for the simulation of impact loads, plasticity and cracking of steel target. An assessment is made for perforation. Three computer programmes NONSAP, MARC and OBAID have been used for comparison. The analytical results are well compared with those available from a model test.
Reasoning With Shapes: Some Observations From a Case Study
Authors: Chakrabarti Amaresh , Wolf Burkhard 
Published: March 2021

Abstract
Reasoning with shapes plays an essential role in mechanical design. Therefore, developing methods and techniques for supporting this activity is an important goal of design research. As a pre-requisite to this, it is crucial to understand how designers create, modify and consolidate shapes, and based on these, to identify areas where they need to be, and can be supported.
The goal of this paper is to report some observations about the influencing factors and processes involved in reasoning with shapes, based on a case study of an in-house design project. Three questions were asked: (i) where did the initial ideas originate and why, (ii) what were the reasons for changing/modifying these, and how these changed, and, (iii) where did this stop and why.
This paper provides a description and the results of the case study, involving observations and analyses of the above steps. The observations indicate that shape generation and modification is more significantly influenced by (i) the initial state of the design, (ii) identification, contextualisation and selection of criteria to apply for evaluation of that design state, and (iii) on the quality of evaluation of the design state, than by the generative changes, which often are simple adaptations of existing solutions.
A Spectral Optimization Algorithm for Multi-Objective Prototype Selection
Authors: Dong Andy , Agogino Alice M. 
Published: March 2021

Abstract
In design synthesis, engineering prototypes make an ideal representation medium for preliminary designs. Unlike parametric design wherein a pre-specified design is parametrically varied, design synthesis demands artistic creativity and engineering experience to transform the previously known components, relationships and designs into a new form. The process compels the designer to ascertain which prototypes will, in some sense, best satisfy the design task. The challenge in this assignment lies in selecting the “right” design prototype. This selection process typically entails an objective evaluation of different designs that perform the same functions or have similar intended behavior and comparing trade-offs between alternate designs. This paper introduces a multi-objective spectral optimization algorithm for the selection of design prototypes based upon their functional representations. The optimization algorithm returns an index of rank, scoring the functional similarity of the proposed design to the goal design. Two illustrative examples apply the algorithm to the selection of a heat fin and beam.
Benchmarking Within the Product Development Process
Authors: Meeker David G. , Thornton Anna C. 
Published: March 2021

Abstract
One cannot design in a vacuum; the goodness of a product is almost always (except in the case of a novel design) measured with respect to an existing design. It is logical, therefore, to have a design process that takes competitors into account. Competitor’s hardware is a rich source of design information providing concept and design solutions, current market trends, cost and quality drivers, missing functionality and unwanted functionality. This paper presents a methodology to systematically evaluate existing designs using a process called benchmarking. In addition, a methodology for incorporating the benchmark information into the specification, concept, embodiment, detail design phases of the product development process is described.
Interactive Feature Recognition Using Multi-Processor Methods
Authors: Regli William C. , Gupta Satyandra K. , Nau Dana S. 
Published: March 2021

Abstract
The availability of low-cost computational power is enabling development of increasingly sophisticated CAD software. Automation of design and manufacturing activities poses many difficult computational problems. Design is an interactive process and speed is a critical factor in systems that enable designers to explore and experiment with alternative ideas. As more downstream manufacturing activities are considered during the design phase, computational costs become problematic. Achieving interactivity requires a sophisticated allocation of computational resources in order to perform realistic design analyses and generate feedback in real time.
This paper presents our initial efforts to use distributed algorithms to recognize machining features from solid models of parts with large numbers of features and many geometric and topological entities. Our goal is to outline how significant improvements in computation time can be obtained using existing hardware and software tools. An implementation of our approach is discussed.
Dynamic Response of a Rotor Landed on Auxiliary Bearings
Authors: Wang Xinchao , Noah Sherif 
Published: March 2021

Abstract
This study concerns the dynamic response of a rotor landed on auxiliary (catcher) bearings in an Active Magnetic Bearing (AMB) supported rotor, following postulated loss of power or overload of the AMB.
An analytical model involving disk, shaft and auxiliary bearings on damped flexible supports is constructed and appropriate equations of the nonlinear dynamic system are developed. The equations include a switch function to indicate contact/noncontact events and determine the existence of contact normal forces and tangential friction forces between the shaft and the bearings.
Steady state solutions are obtained. An analytical method was formulated and used to yield solutions for cases with well balanced rotors, in absence of any side forces. The Fixed Point Algorithm (FPA) is used to obtain steady state periodic solutions for various parameters. The FPA is used to determine the stability of the periodic solution and the type of bifurcations involved. Multiple periodic solutions, quasiperiodic and chaotic responses are detected and discussed. A set of preliminary guidelines for selection of the parameters of the catcher bearings are given.
Experimental Periodic Localized Motions in Coupled Beams With Active Nonlinearities
Authors: King Melvin E. , Aubrecht Johannes , Vakakis Alexander F. 
Published: March 2021

Abstract
Steady-state nonlinear motion confinement is experimentally studied in a system of weakly coupled cantilever beams with active stiffness nonlinearities. Quasi-static swept-sine tests are performed by periodically forcing one of the beams at frequencies close to the first two closely-spaced modes of the coupled system, and experimental nonlinear frequency response curves for certain nonlinearity levels are generated. Of particular interest is the detection of strongly localized steady-state motions, wherein vibrational energy becomes spatially confined mainly to the directly excited beam. Such motions exist in neighborhoods of strongly localized anti-phase nonlinear normal modes (NNMs) which bifurcate from a spatially extended NNMs of the system. Steady-state nonlinear motion confinement is an essentially nonlinear phenomenon with no counterpart in linear theory, and can be implemented in vibration and shock isolation designs of mechanical systems.
Dynamical Behaviour of Hysteretic Systems Under Harmonic Forces
Authors: Capecchi Danilo , Maslani Renato , Vestroni Fabrizio 
Published: March 2021

Abstract
The study of the response of hysteretic systems to harmonic forces is formulated in a suitable phase space in which an originally multi-valued restoring force is represented by proper functions. The asymptotic response can thus be studied using an approach which derives from the Poincaré map concept and avoids approximate analytical techniques. On account of the peculiarity of the hysteretic systems considered, based on Masing rules, the dynamics are studied in a reduced dimension phase space using an efficient solution algorithm. Only the periodic response is taken into account, which is described by frequency response curves at various intensities of the excitation and by the frequency content. The results presented mainly refer to a two d.o.f. system with two linear frequencies in a ratio of 1:3 and 1:4.
The response is highly complex with numerous peaks corresponding to higher harmonics. The range of frequency in which the effects of internal resonance are evident is much larger than the nonlinear elastic case. In particular the coupling produces a strong modification of the frequency response curves and of the oscillation shape of the structure.
Discrete Evolutionary Spectra of Discretized Beams and Plates Under Time-Frequency Modulated Random Excitations
Authors: To C. W. S. , Hung H. W. 
Published: March 2021

Abstract
Various methods that employed the theory of evolutionary spectral density of Priestley (1965) have been proposed for the non-stationary random response analysis of linear time-invariant multi-degree-of-freedom systems (Hammond, 1968, Fugimori and Lin, 1973, To, 1982, Shihab and Preumont, 1987, To and Hung, 1989).
In this paper the method presented earlier by the authors (1989) is further applied to discrete or discretized systems under time-frequency moduated random excitations in which the white noise processes are replaced by band-limited white noise processes and Kanai-Tajimi models. Applications of the method to beam and plate structures discretized by the finite element method are made so as to illustrate its capability in dealing with practical engineering systems under intensive transient disturbances that may be modelled as such time-frequency modulated random excitations.
Efficient Computation of the Statistics of Reciprocating Engine Dynamics With Dimensional Tolerances
Authors: Zhang F. , Sinha A. , Gilmore B. J. 
Published: March 2021

Abstract
Using the alternating frequency/time domain technique and statistical analysis, an efficient analytical technique has been developed to compute the mean values and variances of the crank’s angular speed and driving torque for a stochastically defined internal combustion (I.C) engine. The I. C. engine is represented by a slider-crank mechanism with a discontinuous force on the piston due to the time-varying gas pressure in the cylinder. The tolerances on link lengths and radial clearances and uncertainties in pin location are treated as random variables. The validity of analytical technique is established by comparison with results from Monte Carlo simulation. The results from parametric studies are also presented.
Analysis of Beam-Like Structures With Displacement-Dependent Friction Forces: Part I — Single-Degree-of-Freedom Model
Authors: Whiteman Wayne E. , Ferri Aldo A. 
Published: March 2021

Abstract
The dynamic behavior of a beam-like structure undergoing transverse vibration and subjected to a displacement-dependent dry friction force is examined. In Part I, the beam is modeled by a single mode while Part II considers multi-mode representations. The displacement dependence in each case is caused by a ramp configuration that allows the normal force across the sliding interface to increase linearly with slip displacement. The system is studied first by using first-order harmonic balance and then by using a time integration method. The stick-slip behavior of the system is also studied. Even though the only source of damping is dry friction, the system is seen to exhibit “viscous-like” damping characteristics. A strong dependence of the equivalent natural frequency and damping ratio on the displacement amplitude is an interesting result. It is shown that for a given set of parameter values, an optimal ramp angle exists that maximizes the equivalent damping ratio. The appearance of two dynamic response solutions at certain system and forcing parameter values is also seen. Results suggest that the overall characteristics of mechanical systems may be improved by properly configuring frictional interfaces to allow normal forces to vary with displacement.
Theoretical Dynamic Analysis of a Cantilever Beam Damped by a Dry Friction Damper
Authors: Korkmaz I. , Barrau J. J. , Berthillier M. , Creze S. 
Published: March 2021

Abstract
The dynamic behavior of a cantilever beam damped by dry friction has been studied The beam is represented partly by its effective modal parameters, obtained from a finite element model. The Coulomb friction law is used and a temporal integration of the dynamic response is performed. A detailed parametric study, highlighting the influence of the static and the dynamic friction coefficients, the viscous damping coefficient, the contact stiffness and the position of the damper along the span, on the dynamic response has been conducted. A better understanding of the damping mechanism by dry friction has been obtained. The numerical results have been compared to experimental results, and a good agreement was found. The results could be applied to a turbine blade with a blade to ground damper.
Carbon Brake Friction Model Parameter Identification Using Genetic Algorithms
Authors: von Doenhoff Roger C. , Streifel Robert J. , Marks Robert J. 
Published: March 2021

Abstract
A model of the friction characteristics of carbon brakes is proposed to aid in the understanding of the causes of brake vibration. The model parameters are determined by a genetic algorithm in an attempt to identify differences in friction properties between brake applications during which vibration occurs and those during which there is no vibration. The model computes the brake torque as a function of wheelspeed, brake pressure, and the carbon surface temperature. The surface temperature is computed using a five node temperature model. The genetic algorithm chooses the model parameters to minimize the error between the model output and the torque measured during a dynamometer test. The basics of genetic algorithms and results of the model parameter identification process are presented.
Extraction of Impulse Response Data via Wavelet Transform for Structural System Identification
Authors: Robertson A. N. , Park K. C. , Alvin K. F. 
Published: March 2021

Abstract
This paper presents a wavelet transform-based method of extracting the impulse response characteristics from the measured disturbances and response histories of linear structural dynamic systems. The proposed method appears to have alleviated some of the most pronounced deleterious aspects of both the time-domain methods that suffer from the matrix ill-conditioning of the input signals and FFT-based methods that must cope with erraneous auto and cross-correlation functions, unless the input signals are rich enough in frequency content The method is found to be effective in capturing very low frequency response components and also far insensitive to output noises than existing methods. The present method has been applied to a variety of problems, which show significant improvements over existing impulse response function extraction methods, especially for limited harmonic excitations and input/output data contaminated with noises.
Adaptivity and Three Dimensional Hierarchical Boundary Elements for Rigid Acoustic Scattering Problems
Authors: Newhouse Steven J. , Mathews Ian C. 
Published: March 2021

Abstract
The boundary element method is an established numerical tool for the analysis of acoustic pressure fields in an infinite domain. There is currently no well established method of estimating the surface pressure error distribution for an arbitrary three dimensional body. Hierarchical shape functions have been used as a highly effective form of p refinement in many finite and boundary element applications. Their ability to be used as an error estimator in acoustic analysis has never been fully exploited.
This paper studies the influence of mesh density and interpolation order on several acoustic scattering problems. A hierarchical error estimator is implemented and its effectiveness verified against the spherical problem. A coarse cylindrical mesh is then refined using the new error estimator until the solution has converged. The effectiveness of this analysis is shown by comparing the error indicators derived during the analysis to the solution generated from a very fine cylindrical mesh.
Patching Model for Acoustoelastic Scattering
Authors: Sachs David A. 
Published: March 2021

Abstract
Faceting models have long been used in electromagnetic scattering to achieve target shape generality. An analogous approach to acoustoelastic scattering from submerged shells has been developed. Generalized asymptotic (ray) solutions of the thin shell equations for smooth shells, developed by Norris and Rebinsky, are applied to a discretized geometry representation to analyze the membrane wave contributions to the scattered field from shells excited by incident plane acoustic waves. Example results for a finite cylindrical shell with spherical endcaps are compared to Finite Element calculations. Limitations of the Norris and Rebinsky theory and of the patching methodology are discussed. A major prerequisite for further progress is a hybrid ray/numerical approach to treat the common practical problem of adjoining and interacting ray and non-ray zones.
Acoustic Design of a Local Scatterer in a Phase-Space
Authors: McCoy John J. , Steinberg Ben Zion 
Published: March 2021

Abstract
A spatially local region of mechanical property heterogeneity is a source of scattering, by which a structure-borne mechanical wavefield is released as sound, to a surrounding fluid. We consider the case of a scatterer which is of the order of the size of the wavelength of a plate-wave field for a frequency which is below coincidence. A design strategy for reducing the strength of the scattered sound field in the fluid, at far-field distances from the scatterer, by adding a small-scale structure to the heterogenity, is presented. The design is accomplished in a wavelet-based phase-space. Emphasized is a significant distinction required of the added structure, depending on the heterogeneity applying to a measure of the local mass density or the local bending stiffness.
Bifurcation and Stability Analysis of Parabolic Ray Equations for Acoustic Wave Propagation in an Underwater Sound Channel
Authors: Wiercigroch Marian , Badiey Mohsen , Simmen Jeffrey , Cheng Alexander H.-D. 
Published: March 2021

Abstract
The non-linear dynamic behavior of acoustic wave propagation in underwater sound channel is studied by a parabolic ray theory using Munk’s sound speed profile. The Hamiltonian system of the ray trajectory is forced by a single mode sinusoidal internal wave. The amplitude and wave length of this excitation are used in a bifurcation analysis. The regions of instability are located by numerical simulations and visualized through a sequence of phase diagrams and Poincaré maps.
Scattering of a Plane Acoustic Wave by a Spherical Elastic Shell Near a Free Surface
Authors: Huang H. , Gaunaurd G. C. 
Published: March 2021

Abstract
The acoustic scattering by a submerged spherical elastic shell near a free surface, and insonified by plane waves at arbitrary angles of incidence is analyzed in an exact fashion using the classical separation of variables technique. To satisfy the boundary conditions at the free surface as well as on the surface of the spherical elastic shell, the mathematical problem is formulated using the image method. The scattering wave fields are expanded in terms of the classical modal series of spherical wave functions utilizing the translational addition theorem. Quite similar to the problem of scattering by multiple spheres, the numerical computation of the scattered wave pressure involves the solution of an ill-conditioned complex matrix system the size of which depends on how many terms of the modal series are required for convergence. This in turn depends on the value of the frequency, and the proximity of the spherical elastic shell to the free surface. The ill-conditioned matrix equation is solved using the Gauss-Seidel iteration method and Twersky’s method of successive iteration double checking each other. Backscattered echoes from the spherical elastic shell are extensively calculated and displayed. The result also demonstrates that the large amplitude low frequency resonances of the echoes of the submerged elastic shell shift upward with proximity to the free surface. This can be attributed to the decrease of added mass for the shell vibration.
Scatter, Radiation and Attenuation of Acoustic Waves in Discontinuous Structures
Authors: Wendlandt B. C. H. 
Published: March 2021

Abstract
The acoustic response of inhomogeneous viscous-plastic elastomer layers which are usually described in terms of impedance and resonance behaviour of the major acoustic structures commonly found in sound attenuating layers as applied to underwater structures is discussed with the visco-elastic wave element approach. The ability of the wave element approach to describe conversion of dilatational waves into flexural waves at two and three dimensional structural intersections, including of the type used to support heavy machinery, is demonstrated theoretically and supported by experimentation. Normal and angular reflection, and underwater radiation properties of such systems are discussed. Understanding the acoustic behaviour of such systems and layers is important in developing approaches to quieten sound transmitting structures and reducing echoes from structures underwater.