bluuebunny/crossref_metadata_2025_split huggingface dataset:
Forced Vibrations of an Elastic Plate Interacting With a Layer of Granular Material
Authors: Obodan Y. 
Published: March 2021

Abstract
A variable-structure system, consisting of a thin horizontal elastic plate, loaded by a heavy layer of granular material is considered. The system is excited by prescribed vertical vibrations of the plate boundaries. An essentially nonlinear vibrational rheological model with unilateral constraints is proposed for simulation of the layer behavior. During the coupled motion stages the layer dynamic response on the interface between plate and granular layer is described by the Volterra integro-operator relationship with nonlinear isochronic force-displacement characteristic. The governing set of equations includes the plate dynamics differential equation, an integro-differential equation of the layer dynamics, and also appropriate boundary and initial conditions. Due to utilization of the Galerkin method and Kroosh approximation, the initial set is reduced to the set of nonlinear differential equations. The latter is integrated numerically. Model identification is carried out by the computer processing of the experimental bending strain histories. Influence of the excitation parameters, height of the layer, and damping on the bending strains is analyzed. Adequate simulation of the layer behavior for one-period modes is achieved with regard to the motion periodicity, the values of the strain peaks, the critical time points and the duration of the main time stages. Analysis of numerical phase trajectories and Poincaré sections predicts transition to stochastic vibration modes and the existence of stable two-period limit cycles, when the maximum forcing acceleration is increased above 3g.
Splitting of Separatrices in the Rapidly Forced Duffing Oscillator
Authors: Vakakis Alexander F. 
Published: March 2021

Abstract
The splitting of the stable and unstable manifolds of the rapidly forced Duffing oscillator with negative stiffness is investigated. The method used relies on the computation of analytic approximations for the orbits on the perturbed manifolds, and the asymptotic approximation of these orbits by successive integrations by parts. It is shown, that the splitting of the manifolds becomes exponentially small as the perturbation parameter tends to zero, and that the estimate for the splitting distance given by the Melnikov Integral dominates over high order corrections.
On Minimizing Thermal Deflections of Laminated Plates
Authors: Abrate S. 
Published: March 2021

Abstract
Thermal deflections of symmetrically laminated plates that are continuous over many line supports are determined using the Rayleigh-Ritz method. The constitutive equations and the thermal loads are expressed in terms of four non-dimensional lamination parameters. Layups that minimize thermal deflections are determined for several types of composite plates subjected to temperature increases that vary linearly through the thickness.
Quantification Versus Go/No-Go Criteria
Authors: Brickman Dennis B. , Barnett Ralph L. 
Published: March 2021

Abstract
Compliance or non-compliance with a sound safety code or standard is currently the most rational way of judging whether a product or system is sufficiently safe. Many such codes and standards specify minimum numerical criteria such as loading, tilt angle, and duration time by which compliance may be judged. Usually it is more valuable to make judgements based on quantitative test data as opposed to meeting minimum criteria. For example, a lawn and garden tractor will remain stable when tilted laterally to 28.7° compared with the go/no-go minimum specification of 20°. This paper illustrates the richness of quantification for a number of different products including hook-on high chairs, grinding wheels, structural members, and smoke detectors.
Design Variation Simulation of Thick-Walled Cylinders
Authors: Eggert Rudolph J. 
Published: March 2021

Abstract
Thick-walled cylinders exposed to high, static internal pressures may experience both elastic and plastic deformation. Primary design considerations include loads, geometry and material properties. However, variations in geometry and material properties due to conventional manufacturing processes, and variations of internal pressure due to actual usage patterns, propagate through the system resulting in off-design stresses and strains which may cause failure. These variations can be evaluated using probabilistic methods which are discussed in this paper. Von Mises-distortion energy yield theory is presented to predict elastic, plastic and residual stresses in thick-walled cylinders. The design variation simulation method using Monte Carlo simulation and available statistical information is used to design a pressure vessel for servo-hydraulic experiments. The use of autofrettage to induce favorable compressive stresses at the inner bore, thereby improving the margin of safety and overall reliability, is also presented.
Failure Prediction Using the Ring-on-Ring Test and the CARES/LIFE Integrated Design Program
Authors: Powers Lynn M. , Salem Jonathan A. , Choi Sung R. 
Published: March 2021

Abstract
The integrated design program CARES/LIFE calculates the fast-fracture and time-dependent reliability of monolithic ceramic components subjected to thermomechanical loading. A summary of the program capability is included in the paper. This program is an extension of the CARES (Ceramics Analysis and Reliability Evaluation of Structures) computer program. The results from finite element analysis are used to evaluate component reliability due to inherent surface and/or volume flaws. The two-parameter Weibull cumulative distribution function is used to characterize the variation in component strength. The fast-fracture strength of sintered alpha silicon carbide tested in three- and four-point bend was used to predict the failure strength distribution of ring-on-ring tests. The specimens were tested in the annealed conditions. CARES/LIFE predicted the biaxial failure accurately when the noncoplanar strain energy release rate criterion was applied. For time-dependent life prediction, dynamic fatigue ring-on-ring test data on soda-lime glass is used to demonstrate the fatigue parameter estimation capability of CARES/LIFE.
Thermal Shock and Fatigue Behavior of Ceramic Tubes
Authors: Segall A. E. , Hellmann J. R. , Tressler R. E. 
Published: March 2021

Abstract
A narrow circumferential helium quench was used to thermally shock and fatigue internally heated alumina, reaction bonded, and sintered alpha silicon carbide tubes at 500°C and 1000°C. During these tests, transient temperature measurements required for thermal and stress-profile calculations were obtained through the use of micro-thermocouples positioned along the internal surface of the tubes. Acoustic emissions were also employed for in situ monitoring of crack initiation and propagation of the resident flaw populations during the single and repeated (up to 5) thermal shocks. Post-quench inspections and destructive burst tests were used to correlate the existence, extent, and statistical (Weibull) nature of the damage induced by the cycling. Results indicated progressive strength degradation in alumina tubes with repeated thermal cycles. In contrast, the thermally-cycled silicon carbide samples either showed no damage at all, or suffered minimal progressive strength degradation after the first cycle. In any case, the complex stress distributions computed from an FEA-based inverse heat transfer analysis were required to understand the observed damage (crack paths) and apparent fatigue behavior.
Fatigue Evaluation in Ceramic Materials by Acoustic Emission
Authors: Jadaan Osama M. , Liu K. C. , Pih H. 
Published: March 2021

Abstract
Progressive damage due to tension-tension cyclic fatigue loading for three distinct ceramic materials was evaluated using the acoustic emission (AE) technique. The objective of this study was to determine the capabilities of the AE method to detect the imminence of failure and to locate potential fracture sites. Results indicated that the AE technique was capable of predicting failure by showing an increase in energy/count rate prior to failure. Although potential fracture sites can be identified, exact location of the final fracture site can be known only when catastrophic failure takes place.
Fatigue Behavior of Adhesive Joints Under Biaxial Loading Conditions
Authors: Sancaktar Erol 
Published: March 2021

Abstract
Fatigue data obtained under biaxial loading conditions for adhesively bonded joints are used to plot S-N type diagrams to assess the effects of biaxiality in loading. Independently Loaded Mixed-Mode Specimens (ILM MS) are used for data collection purposes. These specimens are basically two (steel) beams bonded to be fatigue loaded under cantilever (opening) mode while a simultaneous but physically separate in-plane (static) shear load is also induced with the aid of a small hydraulic piston embedded in the specimen. Application of such static shear loads results in different S-N behavior for the bonded joint. The model adhesives used are Metlbond 1113-2 and Metlbond 1113 solid film thermosetting adhesives similar to those commonly used in aircraft and aerospace industries. The former is an elastomer-modified epoxy adhesive and the latter is identical except that it containes a synthetic earner cloth. Thus, the effects of carrier cloth in adhesive’s S-N behavior is also assessed. Analytically, the classical linear log-log representation of the adhesive S-N data is explored and modifications necessary to reflect the effects of biaxiality in loading and also the presence of a carrier cloth are assessed. The fatigue failure results are also compared with results obtained under monotonic biaxial loading conditions.
Approximate Residual Interface Compression in a Laminated Magnet
Authors: Jahanian Shahriar , McPhate A. J. 
Published: March 2021

Abstract
Present design of large laminated magnets are based on effective modulus of elasticity for the plate stack that is invariant with interplate compression. Experimental results indicates this is not a valid assumption. This analysis considers the specific design used for compact electron storage ring dipole magnet at the Center for Advanced Micro Devices (CAMD) at Louisiana State University. An iterative technique, using FEM is developed to approximate the effective modulus throughout the magnet structure. This particular magnet is constructed from 1424 steel plates (1.5mm × 610mm × 780mm) by first compressing a 45° 2.93m raduis curvilinear stack to a specified preload and then welding straight and curved straps to the exterior of the stack. Release of the preload allowsexpansion of the stack and forces stretch of the straps, the resultant interplate compression is considerably different from the initial preload and varies throughout the magnet.
The analysis technique introduced in this paper is a simplified approach to the interplate compression modeling and consists of the supeposition of two simple analysis; one with straps attached, one without straps attached. An iterative approach is used to incorporate the dependence of effective compressive modulus on the interplate compression. An estimate of the average modulus is assumed for the entire stack and residual compression is calculated. From this residual compression and from experimental data, a distribution of compressive modulus throughout the magnet is computed. From this computed distribution, a new estimate for the compressive modulus is made for each element of the model and the analysis iterated. The net results are the compressive modulus distribution throughout the magnet ia a form suitable in subsequent dynamic analysis.
An Overview of Elevated Temperature Damage Mechanisms and Fatigue Behavior of a Unidirectional SCS-6/Ti-15-3 Composite
Authors: Castelli Michael G. , Gayda John 
Published: March 2021

Abstract
The fatigue behavior of a unidireclionally reinforced titanium matrix composite (TMC), SiC/Ti-15-3, was thoroughly characterized to support life prediction modeling of advanced TMC disks designed for gas turbine engine rotor applications. The results of this coupon-level experimental investigation are reviewed in this paper. On a stress basis, the isothermal fatigue behavior of the [0°] TMC revealed significant improvements over the unreinforced matrix. In contrast, the [90°] TMC exhibited degraded properties and lives for similar comparisons. This was attributed to the weak fiber/matrix interfacial bond. Encasing the [0°] TMC with a Ti-15-3 case did not affect isothermal fatigue lives at higher strain levels. However, at lower strain levels, relatively rapid initiation and propagation of large fatigue cracks in the case degraded the fatigue lives. Thermomechanical fatigue (TMF) lives were significantly reduced for the [0°] TMC when compared to isothermal lives. At high strains, in-phase TMF produced extremely short lives. This degradation was attributed to fiber overload failures bought about by stress relaxation in the matrix. At low strains, out-of-phase TMF conditions became life-limiting. Environment-assisted surface cracking was found to accelerate fatigue failure. This produced extensive matrix damage with minimal fiber damage. For the [90°] TMC, TMF conditions did not promote an additional degradation in cyclic life beyond that observed under isothermal conditions.
A Deformation and Life Prediction of a Circumferentially Reinforced SiC/Ti 15-3 Ring
Authors: Arnold S. M. , Wilt T. E. 
Published: March 2021

Abstract
A computational methodology has been developed to predict the fatigue life of typical aerospace components, here the specific example is a circumferentially reinforced SiC/Ti-15-3 compressor ring designed for applications at 800° F. The analysis encompasses both a static burst pressure prediction and a life assessment of the cladded ring. A three dimensional stress analysis was performed using MARC, a nonlinear finite element code, wherein both the matrix cladding and the composite core were assumed to behave elastic-plastic. The composite core behaviour was represented using Hill’s anisotropic continuum based plasticity model with bilinear hardening. Similarity, the matrix cladding was represented by an isotropic perfectly plastic model. The load-displacement (i.e., internal pressure versus radial deflection) response of the ring was used to determine the static burst pressure.
The life assessment was conducted using the stress analysis results, in conjunction with a recently developed multiaxial, isothermal, continuum damage mechanics model for the fatigue of unidirectional metal matrix composites. This model is phenomenological, stress based, and assumes a single scalar internal damage variable, the evolution of which is anisotropic. The accumulation of damage is included in the stress analysis by employing the concept of effective stress. In the current application, however, the damage model is computationally-decoupled from the finite element solution. The specific methodology for this computationally-decoupled fatigue damage simulation is outlined and results are given in terms of the evolution of damage and design life curves.
NDE of Titanium Alloy MMC Rings for Gas Turbine Engines
Authors: Baaklini George Y. , Percival Larry D. , Yancey Robert N. , Kautz Harold E. 
Published: March 2021

Abstract
Progress in the processing and fabrication of metal matrix composites (MMC’s) requires appropriate mechanical and non-destructive testing methods. These methods are needed to characterize properties, assess integrity, and predict the life of engine components such as compressor rotors, blades, and vanes. For this paper, we investigated the capabilities and limitations of several state-of-the-art nondestructive evaluation (NDE) technologies in characterizing titanium MMC rings for gas turbine engines. We examined the use of NDE technologies such as x-ray computed tomography, radiography, and ultrasonics in identifying fabrication-related problems that cause defects in components. Acousto-ultrasonics was explored to assess degradation of material mechanical properties by using stress wave factor and ultrasonic velocity measurements before and after the burst testing of the rings.
We concluded that radiography and pulse-echo ultrasonics are viable imaging techniques for fast and complementary evaluation of the rings. Furthermore, acousto-ultrasonics can be useful in a comparative analysis with a standard ring and for intermittent evaluation during the life of the rings. X-ray computed tomography can identify the manufacturing steps resulting in poor quality components, guide machining of components to final dimensions, and lead structural and design engineers to realistic component life-prediction models.
Automated Design Tool for Examining Microelectronic Packaging Design Alternatives
Authors: Chin Siew-Wei , Rajan Subramaniam D. , Nagaraj Ben K. , Mahalingam Mali 
Published: March 2021

Abstract
Microelectronic packaging design issues have been given greater attention mainly because the performance, reliability and cost of semiconductor chips are increasingly dictated by the choice and design of the package. The task of integrating the requirements imposed by different disciplines such as mechanical and thermal issues in an automated design tool, is discussed in this paper. Finite element analysis and nonlinear programming techniques are used in an iterative fashion to progress from an initial design concept to a design that satisfies all design requirements or one that is superior to other design alternatives. Two packaging design examples serve to illustrate the functionalities of the automated design optimization tool.
Computational Simulation of Hot Composite Structures
Authors: Chamis C. C. , Murthy P. L. N. , Singhal S. N. 
Published: March 2021

Abstract
Computational procedures are described to simulate the thermal and mechanical behavior of high temperature metal matrix composites (HT-MMC) in the following three broad areas: (1) behavior of HT-MMC from micromechanics to laminate via Metal Matrix Composite Analyzer (METCAN), (2) tailoring of HT-MMC behavior for optimum specific performance via Metal Matrix Laminate Tailoring (MMLT), and (3) HT-MMC structural response for hot structural components via High Temperature Composite Analyzer (HITCAN). The complex composite material behavior, static/fatigue life, and failure sequence of SiC/Ti ring was simulated. The observed experimental degradation in strengths of the SiC/Ti composite with increasing temperature was accurately predicted. The static/fatigue life of the SiC/Ti ring starting with the fabrication process cool-down and subjected to simulated internal pressure was predicted in terms of cyclic-stress-to-static strength-ratio versus cycles to failure.
On Interaction of Eigenvalue Branches in Non-Conservative Multi-Parameter Problems
Authors: Seyranian Alexander P. , Pedersen Pauli 
Published: March 2021

Abstract
In this paper two interesting mechanical (physical) phenomena are considered. The first one is the phenomenon of transference of instability between branches. The second phenomenon is the destabilization effect due to infinitely small damping. The considerations and the explanations are given from the point of view of behaviour of eigenvalue branches in the vicinity of a double eigenvalue. These questions are close connected with sensitivity analysis of non conservative systems subjected to instability phenomena, and thus the present work is a continuation of our earlier published joint research. Also the extended information available by Hurwitz determinants is focused on.
Nonlinear Response of a Clamped Plate to Nonstationary Excitation: Experiments and Theory
Authors: McCabe Sarah A. , Chang Seo I. , Davies Patricia , Bajaj Anil K. 
Published: March 2021

Abstract
The paper contains a description of a series of experiments conducted on a thin rectangular plate. The initial objective of the experiments was to observe behavior predicted by theoretical studies and observed in simulations of the plate response. The theoretical work centered on predicting the behavior of plates having modes with coincident natural frequencies and driven with a constant sinusoidal excitation. Of particular interest was the modal coupling, due to nonlinearities, which give rise to the possibility of a coupled mode response when only a single mode is excited. Experimental constraints, and the sensitivity of the plate in configurations where more than one mode of response is possible, meant that the best experimental excitation of the plate would be a sine wave with a very slowly varying frequency. A PC based signal generator was developed to drive an array of loudspeakers so that particular modes of the plate could be strongly excited, and the frequency of excitation could be varied. To gain an understanding of the behavior of the plate when the excitation is nonstationary, the theoretical analysis of the plate behavior was extended to incorporate sinusoidal excitation where the frequency varied with time. The results of the analysis is a prediction of the response amplitude for slow and relatively fast swept sine wave excitations. In the paper, the qualitative features of the experimental response amplitudes are compared to those predicted by theory.
Effect of Coupler Material Damping on Steady-State Response Calculation of Elastic Mechanisms
Authors: Chivate Pramod N. , Farhang Kambiz 
Published: March 2021

Abstract
This paper presents an investigation of the steady-state response of flexible mechanisms. Two methods are utilized to obtain the steady-state response for the flexible coupler of a slider-crank mechanism with varying degrees of material damping. The first method, based on a sixth-order Runge-Kutta formulation, is shown to be effective only for high values of material damping. The second method, which utilizes the discretization of the fundamental time period of response, is found to be effective and efficient for obtaining the steady-state response at all damping values. Algorithm results for high as well as low operating speeds are shown to be in good agreement with the Runge-Kutta method of integration. For the case of very low damping, system response is found to be aperiodic. Using the Poincare’ mapping technique, the aperiodicity is investigated and is found to be mainly due to the Runge-Kutta integration technique.
Effect of Meshing Parameters on the Dynamic Loads of a Mechanism With Spur Gears
Authors: Belnikolovsky Boris G. , Cheshankov Bozhidar I. , Abuid Bader A. 
Published: March 2021

Abstract
In the model used inertias of motor, machine and the gear wheels, stiffness of shafts and bearing and damping are considered. In the meshing zone, the variable stiffness of teeth, pitch error, tooth deflection, tooth modification and impact between teeth are included. Differential equations of motion are written and solved analytically and numerically. Based on the good agreement between the analytical and the numerical results, a dynamic analysis for the effect of many parameters of meshing, such as pitch error, tooth modification, module, contact ratio, tooth width and the gear ratio on the dynamic loads is made.
Use of a Pendulum for Passive Structural Vibrations Control: An Experimental Study
Authors: Ertas A. , Cuvalci O. 
Published: March 2021

Abstract
The dynamic response of a beam-tip mass-pendulum system subjected to sinusoidal excitations is considered. The conditions under which resonant and nonresonant oscillations occur are investigated and discussed. The main objective of this study was to conduct a series of experiments to investigate the autoparametric interaction between the first two modes of the system. The use of a pendulum as a passive control device was experimentally evaluated.