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Full-Text Articles in Mechanical Engineering

Ultrasonic Nde Of Thick Composites, R. Bruce Thompson, Donald O. Thompson, David K. Holger, David K. Hsu, M. S. Hughes, Emmanuel P. Papadakis, Yu-Min Tsai, Loren W. Zachary Dec 1991

Ultrasonic Nde Of Thick Composites, R. Bruce Thompson, Donald O. Thompson, David K. Holger, David K. Hsu, M. S. Hughes, Emmanuel P. Papadakis, Yu-Min Tsai, Loren W. Zachary

Aerospace Engineering Conference Papers, Presentations and Posters

A series of ultrasonic techniques being developed for the characterization of thick composites are described. Techniques for the in-situ measurements of elastic constants on thick-walled cylinders based on the times of a variety of ultrasonic modes of propagation are first presented, followed by discussion of the determination of the porosity from measurements of the frequency dependence of the attenuation. Two techniques for imaging delamination are then discussed. The first involves inferring size from plots of reflected signal amplitude versus lateral position of the transducer with a model for beam propagation in anisotropic media used to deconvolve the effects of the ...


Synthesis And Analysis Of Elastic High-Speed Cam-Operated Mechanisms , Hsin-Ting Jonathan Liu Jan 1991

Synthesis And Analysis Of Elastic High-Speed Cam-Operated Mechanisms , Hsin-Ting Jonathan Liu

Retrospective Theses and Dissertations

In the synthesis of high-speed cam profiles, we must compensate for the elastic deflections induced by large inertial effects generated during operation. Thus, differential equations with kinematic constraints need to be solved. The governing dynamic equations are in homogeneous, periodic, linear, ordinary differential equations which possess multiple unstable and high vibrational regions at various operating speed zones. These regions are found to be intrinsically determined by the changing geometry of the follower linkage during operation;This dissertation considers two types of cam driven linkages. Parts I and II consider a cam driving a lumped inertia through a massless elastic slider-crank ...


Ionic Structure Of Methane Flames , Timothy Wayne Pedersen Jan 1991

Ionic Structure Of Methane Flames , Timothy Wayne Pedersen

Retrospective Theses and Dissertations

The objective of this research was to predict the structure of ions generated in methane flames. These simulations might lead to a better understanding of the interactions between ions in hydrocarbon flames. It was thought that such an understanding could lead to technology for electrically controlling combustion processes, formation of soot, and heat transfer;The reaction mechanisms used in this study was for a methane or hydrogen/methane flame. It contains reactions for the oxidation of fuels, chemiionization, ion-molecule reactions, and dissociative recombination. A computer model was developed to evaluate the formation of ions based on the proposed reaction mechanism ...


The Ultrasonic Measurement Of Stress On Ferrous Plate Using Pulsed Electromagnet Magnetostrictive Emat Probes, S. J. Wormley, R. Bruce Thompson, Yan Li Jan 1991

The Ultrasonic Measurement Of Stress On Ferrous Plate Using Pulsed Electromagnet Magnetostrictive Emat Probes, S. J. Wormley, R. Bruce Thompson, Yan Li

Review of Progress in Quantitative Nondestructive Evaluation

Last year we finished the design and assembly of a semi-automatic system for the measurement of stress in textured ferritic steel[2], Magneto- strictive EMATs, which have no contributions generated by Lorentz force, were used on ferrous alloys since the absence of the Lorentz force mechanism precludes any velocity errors that might be produced by interference of Lorentz force and magnetostrictively generated signals. Phase shifts due to lift-off were solved by driving the transmitter EMAT’s in series. To make reliable wave-speed measurements in an industrial environment with an economical sampling period of 100 nanoseconds, a Fourier Transform-Phase-Slope technique was ...


A Parametric Finite Element Study Of A Generic Crack Sizing Problem, M. G. Wismer, P. L. Levin, R. Ludwig Jan 1991

A Parametric Finite Element Study Of A Generic Crack Sizing Problem, M. G. Wismer, P. L. Levin, R. Ludwig

Review of Progress in Quantitative Nondestructive Evaluation

This paper discusses the application of a numerical analysis technique to study eddy-current transducers. Probe design and operating parameters are determined by the constraints of excitation current and the material being tested Because the depth of penetration of the induced eddy-current is related to the excitation frequency as well as the permeability and conductivity of the specimen, the operating frequency may be selected for a certain depth of resolution. However, subsurface field depth is also a function of relative probe size and lift-off. Although there are no known closed form solutions relating probe size and lift-off to penetration, approximate analytical ...


The Effect Of Equipment Bandwidth And Center Frequency Changes On Ultrasonic Inspection Reliability: Are Model Results Too Conservative? (A), R. L. Hockey, E. R. Green, A. A. Diaz Jan 1991

The Effect Of Equipment Bandwidth And Center Frequency Changes On Ultrasonic Inspection Reliability: Are Model Results Too Conservative? (A), R. L. Hockey, E. R. Green, A. A. Diaz

Review of Progress in Quantitative Nondestructive Evaluation

Reliable detection and sizing of material defects, which have been found in nuclear reactor piping and pressure vessels, has been shown [1,2] to be greatly affected by changing components of ultrasonic inservice inspection (UT/ISI) systems. The work reported here, in conjunction with our previous work [3–5], focuses on: providing a more rigorous analysis of equipment interaction and establishing a technical basis for current standards [6] for equipment operating tolerances which, before this work, were based on engineering judgement.


Interface Characterization By True Guided Modes, Peter B. Nagy, Laszlo Adler Jan 1991

Interface Characterization By True Guided Modes, Peter B. Nagy, Laszlo Adler

Review of Progress in Quantitative Nondestructive Evaluation

Guided acoustic waves along interfaces are especially sensitive to specific properties associated with boundary conditions and bond quality since their energy is effectively confined to the region of interest. On the other hand, this inherent advantage turns out to be a significant drawback for generation and detection of such guided waves. There are two basic types of propagating interface modes, which are shown schematically in Figure 1. First, there are leaky modes with higher phase velocity than at least one of the bulk velocities in the surrounding media. These modes “leak” their energy into one or more phase-matching bulk modes ...


The Reflection Of Ultrasound From Interface Layers In Adhesive Joints, Tom Pialucha, Peter Cawley Jan 1991

The Reflection Of Ultrasound From Interface Layers In Adhesive Joints, Tom Pialucha, Peter Cawley

Review of Progress in Quantitative Nondestructive Evaluation

The detection of a weak adhesive/adherend interface in an adhesive joint is one of the major current challenges in NDE; the lack of a satisfactory non destructive test for this region is retarding the exploitation of the advantages of adhesive bonding in safety critical areas. It is the interface layer which is affected by the common problem of slight contamination due to, for example, grease on the adherend surfaces prior to bonding. The interface is particularly important in aluminium-aluminium joints in which an inappropriate interface structure can cause greatly enhanced susceptibility to environmental attack [1]. Inspection of the interface ...


Ultrasonic Reflectivity Determination Of Interfacial Properties In Adhesive Joints Of Aluminum Alloys, W. Wang, B. Li, S. I. Rokhlin Jan 1991

Ultrasonic Reflectivity Determination Of Interfacial Properties In Adhesive Joints Of Aluminum Alloys, W. Wang, B. Li, S. I. Rokhlin

Review of Progress in Quantitative Nondestructive Evaluation

In studies of ultrasonic measurements of interfacial properties, it has previously been proposed [1] that an ultrasonic wave that produces shear stress on the interphase is sensitive to interphase properties. This may be achieved by utilization of interface waves [1,2] or guided waves in the bonded plates [3–5]. Another possibility is the use of obliquely incident ultrasonic waves for interphase evaluation, analyzing signals in the time or frequency domains [6–8].


Characterization Of Glued Bonds Using Ultrasonic Reflected Beam, A. Jung, Ph. Guy, A. Nayfeh, G. Quentin, J. C. Le Flour Jan 1991

Characterization Of Glued Bonds Using Ultrasonic Reflected Beam, A. Jung, Ph. Guy, A. Nayfeh, G. Quentin, J. C. Le Flour

Review of Progress in Quantitative Nondestructive Evaluation

Adhesive bonds of laminates of metal and polymer have been extensively studied using ultrasonic techniques. The strength of the bond is of primary importance and many studies have been aimed at deducing this property from ultrasonic measurements. The quality of adhesively joined structures is mainly determined by two types of factors: i) the cohesive strength of the glue ii) the adhesive strength of the metal-glue interface. To address the last type, several ultrasonic techniques using mainly plate and interface waves have been recently considered [1–4]. Their main advantage, compared to longitudinal or shear waves, is that they are very ...


Sonic Inspection Of Bonds In Viscoelastic Composites, A. F. Emery Jan 1991

Sonic Inspection Of Bonds In Viscoelastic Composites, A. F. Emery

Review of Progress in Quantitative Nondestructive Evaluation

Vibration isolation is frequently accomplished by placing rubber pads between a structure and its foundation. In typical industrial situations, the weight of the structure can be used to keep the pads in place and to ensure contact at the interface. However, when dampers are used for small electronic components, they are frequently glued to the component and to the support. The total unit then consists of the component, a glue interface, the rubber damper, a second glue interface, and the foundation. If the interfaces fail, compressive waves can usually be transmitted, but tensile stress waves encounter the separated layer which ...


Impedance Profiling For Bond Strength Evaluation, Nadir Saffari, David T. Green Jan 1991

Impedance Profiling For Bond Strength Evaluation, Nadir Saffari, David T. Green

Review of Progress in Quantitative Nondestructive Evaluation

Measurement of the strength of adhesive bonds in multi- layered structures is of increasing importance. Ultrasonic NDE methods do not directly determine the strength of a bond but indicate characteristics of a bond which may be related to bond strength through empirical relationships. One such bond characteristic is its acoustic impedance. Impedance profiling methods have long been studied in the field of geophysics and medical ultrasonics [1,2]. In this paper the development of an inversion algorithm based on the so called Goupillaud equal travel-time method is described [3], with the aim of applying it to the NDE of adhesive ...


Application Of Lamb Waves For Evaluation Of Lap-Shear Adhesive Joints, S. I. Rokhlin Jan 1991

Application Of Lamb Waves For Evaluation Of Lap-Shear Adhesive Joints, S. I. Rokhlin

Review of Progress in Quantitative Nondestructive Evaluation

Methods for nondestructive evaluation of adhesive joints have been extensively discussed in the literature because of the technological importance of the problem and the extreme difficulty of evaluation of interphasial properties [1]. Several methods have been proposed for adhesive joint interphase evaluation: ultilization of interphase [2,3] or guided [4–8] waves in the bonded plates or use of obliquely incident ultrasonic waves analyzing signals in the time or frequency domains [9–14]. Most of the above studies (except [5]) have evaluated the adhesive bond in bonded areas away from the sample edges. Even when the configuration of the experimental ...


An Ultrasonic Resonance Method To Determine The Acoustic Velocity Of Thin Adhesive Layers, E. C. Johnson, S. J. Sherman Jan 1991

An Ultrasonic Resonance Method To Determine The Acoustic Velocity Of Thin Adhesive Layers, E. C. Johnson, S. J. Sherman

Review of Progress in Quantitative Nondestructive Evaluation

The development of this ultrasonic method for determining the modulus of thin adhesive layers was motivated by the recent development of a nonintrusive ultrasonic Liquid Level Sensor (LLS) which meets military specifications for space launch [1,2]. The sensor is designed to signal when the surface of the fuel in a liquid propellant tank has receded to the level of the sensor during flight. As depicted in Fig. 1, the sensor is bonded to the outer tank wall with Versilok 202 (V202) adhesive [3]. To detect the fuel level, the sensor is stimulated to propagate an ultrasonic pulse into the ...


Numerical Comparison Of Experimentally Measured Ultrasound Through A Multilayered Specimen, John M. Sullivan Jr., Reinhold Ludwig, Yiping Geng, Vinod K. Nair Jan 1991

Numerical Comparison Of Experimentally Measured Ultrasound Through A Multilayered Specimen, John M. Sullivan Jr., Reinhold Ludwig, Yiping Geng, Vinod K. Nair

Review of Progress in Quantitative Nondestructive Evaluation

The integrity of bonded structures is of paramount importance in the safe and reliable operation of aircraft equipment. Fuselages, helicopter rotor blades and nose cones are multilayered composite structures bonded together. The operational readiness and security of these units depend to a large extent on the integrity of the interfacial bonds. Adhesive and cohesive strength studies do not appear promising because failure is really dominated by defects and not by some average physical properties of the adhesive and the interface [1].


Wave Scattering By An Inclusion Having Imperfect Interfaces With The Matrix, Jianmin Qu Jan 1991

Wave Scattering By An Inclusion Having Imperfect Interfaces With The Matrix, Jianmin Qu

Review of Progress in Quantitative Nondestructive Evaluation

Ultrasonic waves have been used in recent years to detect defects and damages in fiber-reinforced composite materials (see [1] for relevant references). A priori knowledge of how sound wave propagates through the composite medium is essential for using ultrasonic techniques in nondestructive evaluation. In the past, the problern of scattering by inclusions, such as fibers, has been studied extensively [2]–[3]. Most of the studies in the literature assume that the inclusions are perfectly boned to the matrix. However, defects are likely to exist along the fiber—matrix interfaces. As more interfacial defects are initiated, damages are developed within a ...


Analysis Of Bond Quality By Resonant Ultrasound, William M. Visscher, Alburt Migliori, Raymond D. Dixon Jan 1991

Analysis Of Bond Quality By Resonant Ultrasound, William M. Visscher, Alburt Migliori, Raymond D. Dixon

Review of Progress in Quantitative Nondestructive Evaluation

Analysis of the response of small samples of materials to mechanical excitations at ultrasonic frequencies (resonant ultrasound spectroscopy, or RUS) can yield much information about the sample, including its geometry, density (densities, if composite), and elastic constants. (1–5) In this paper, we sketch the experimental technique, the method by which the data can be analyzed, and extend the analysis to samples which comprise two different materials bonded together. In the latter case the technique can give information about the composition of the sample and bond integrity (i.e. whether or not displacements and stresses are continuous across the interface ...


Non-Destructive Evaluation In Manufacturing Using Spectroscopic Ellipsometry, John A. Woollam, Paul G. Snyder Jan 1991

Non-Destructive Evaluation In Manufacturing Using Spectroscopic Ellipsometry, John A. Woollam, Paul G. Snyder

Review of Progress in Quantitative Nondestructive Evaluation

The manufacture of optical coatings, computer disks, as well as advanced electronic multilayered devices and circuit structures requires high precision in the measurement and control of thicknesses and interfacial and surface roughnesses. Variable angle spectroscopic ellipsometry (VASE) is non-destructive and monolayer sensitive. VASE uses polarized light, and the technique can be applied in nearly any ambient, including air, vacuum, or corrosive environment. Applications to coated window glass, space protective coatings, semiconductor device, as well as sputtered media computer disk manufacturing are discussed. At the present time these NDE measurements are mainly ex situ, but in situ (during deposition) applications are ...


Eddy-Current Technique For Sub-Surface Temperature Measurement In A Cast Steel Strand, Guy Wiliams Jan 1991

Eddy-Current Technique For Sub-Surface Temperature Measurement In A Cast Steel Strand, Guy Wiliams

Review of Progress in Quantitative Nondestructive Evaluation

Temperature measurement is critical to the understanding and control of the solidification process in continuous steel casting. Many of the casting variables (for example, state, hot strength and ductility, microstructure) are strongly temperature dependant. A knowledge of temperature will also be required for energy management, particularly if further hot processing of the cast steel is to be performed. Although inferences can be drawn from mathematical modeling studies, direct measurement is required to validate these models, or to improve their accuracy, particularly if the models are used for process control. This paper describes work carried out at BHP MRL in the ...


Cross Section Measurement Of Long Cylindrical Products Without Contact Using Long Cylindrical Coils, B. De Halleux, B. Limburg De Stimm, P. Dumont, R. Van De Wyngaert Jan 1991

Cross Section Measurement Of Long Cylindrical Products Without Contact Using Long Cylindrical Coils, B. De Halleux, B. Limburg De Stimm, P. Dumont, R. Van De Wyngaert

Review of Progress in Quantitative Nondestructive Evaluation

The impedance Z of a solenoid with a conducting piece near it when capacity effects are neglected is Z = R + jωL with (1) R=Re−NωφosinϕIo (2) L=NωφocosϕIo where Re is the resistance of the wire of the coil, N is the number of single turns of the coil, Φo is the amplitude of the mean magnetic flux crossing the coil, Io is the amplitude of the current I circulating in the coil, ω is the pulsation of the current and ϕ is the phase of the flux relative to the current.


Real-Time Radiographic Investigation Of Weld Pool Depression, A. C. Guu, S. I. Rokhlin Jan 1991

Real-Time Radiographic Investigation Of Weld Pool Depression, A. C. Guu, S. I. Rokhlin

Review of Progress in Quantitative Nondestructive Evaluation

Real-time radiography has been utilized by us previously as a vision system in remote arc welding process monitoring [1]. Direct information on weld penetration extracted from real-time radiographic images of the solidified weld was used in feedback to adjust the welding conditions to maintain weld quality [2]. The disadvantage of this method is the time (and space) delay in extracting information on weld penetration which leads to the appearance of small weld areas with lack of penetration. In subsequent work weld penetration was controlled by the use of radiographic information on weld pool depression to eliminate the time delay thus ...


Process Monitoring Techniques Using Acoustic Waves, Sanjay Bhardwaj, B. T. Khuri-Yakub Jan 1991

Process Monitoring Techniques Using Acoustic Waves, Sanjay Bhardwaj, B. T. Khuri-Yakub

Review of Progress in Quantitative Nondestructive Evaluation

Process monitoring and control of semiconductor fabrication parameters, like film thickness, are important issues, limited at the present time by a lack of adequate sensors. In this paper, we outline the limitations of current film thickness technology and propose two new methods for nondestructive film thickness process monitoring: acoustic time domain reflectometry (TDR) and acoustic reflection coefficient phase measurements. Theoretical calculations and experimental measurements of different metal films are used to demonstrate the viability of these novel techniques.


Nuclear Power Plant Costs As A Function Of Nde Reliability, Michael J. Avioli Jr., Soung-Nan Liu Jan 1991

Nuclear Power Plant Costs As A Function Of Nde Reliability, Michael J. Avioli Jr., Soung-Nan Liu

Review of Progress in Quantitative Nondestructive Evaluation

The economic efficiency and safety of any power plant depends on the proper functioning of its component systems. The functioning of such systems (e.g., piping) is evaluated through performance of periodic nondestructive examinations (NDE). The results of these examinations determine actions the power plant owner must take regarding inspected components. If a component is found malfunctioning or containing a defect, the owner may decide to repair or replace the component. If the results of NDE indicates that the component is functioning as it should or is defect-free, he would most certainly take no action but to record such a ...


Manufacture Of Reference Defects For Nde Through Hot Isostatic Pressing, A. N. Sinclair, M. Graf, V. Dasilva, M. D. C. Moles, M. Doleby, S. Kramer, A. L. Allen Jan 1991

Manufacture Of Reference Defects For Nde Through Hot Isostatic Pressing, A. N. Sinclair, M. Graf, V. Dasilva, M. D. C. Moles, M. Doleby, S. Kramer, A. L. Allen

Review of Progress in Quantitative Nondestructive Evaluation

Nondestructive Evaluation techniques such as eddy current or ultrasonics do not give a direct visual indication of the key characteristics of a flaw. Some form of signal interpretation is required in order to determine flaw type, size, and shape. One tool that is frequently employed in the field is the “reference defect”; in the case of ultrasonic testing, reference defects typically consist of notches and flat-bottom or side-drilled holes in a calibration block. Not only are these artificial sound reflectors used to aid in the interpretation of flaw signals, but they may also be used to check that the NDE ...


Thin Bondline Measurement Of Adhesively Bonded Metallic Aircraft Structures Using An Ultrasonic Analyzer, Woody Wongwiwat, Robert Rizzo, Donald Rigney Jan 1991

Thin Bondline Measurement Of Adhesively Bonded Metallic Aircraft Structures Using An Ultrasonic Analyzer, Woody Wongwiwat, Robert Rizzo, Donald Rigney

Review of Progress in Quantitative Nondestructive Evaluation

The use of adhesive bonding for the assembly of aircraft structure is desirable because of the associated benefits of reduced weight, decreased parts count and increased fatigue life. The inability to fully characterize the nature of the bondline has been a limiting factor in applying this technology to the manufacture of primary aircraft structure. One such obstacle is the resolution limitation that has existed for the non-destructive measurement of bondline thicknesses. Up to the present time, ultrasonic methods have been limited in practice to a resolution approximately equal to the wavelength of the energy pulse employed. For a 15 MHz ...


Numerical Simulations Of Thermal Detection Of Disbonds In Lap Joints, P. A. Howell, William P. Winfree, B. Scott Crews Jan 1991

Numerical Simulations Of Thermal Detection Of Disbonds In Lap Joints, P. A. Howell, William P. Winfree, B. Scott Crews

Review of Progress in Quantitative Nondestructive Evaluation

The detection of disbonds in riveted lap joints is of increasing interest to the aerospace community. For some cases a disbonded lapjoint gives rise to cracks at the rivets due to stress concentrations in the aluminum skin when the lapjoints are loaded. When a number of these cracks exist they have been known to suddenly link up and cause sudden failure of the part. Thermographic detection of these disbonds has advantages over other methods in that it is a noncontacting, quantitative method which can inspect large areas in a short period of time. By even application of heat to the ...


Characterization Of Diffusion Bonds Using An Acoustic Microscope, Amit K. Som, Leonard J. Bond, Kevin J. Taylor Jan 1991

Characterization Of Diffusion Bonds Using An Acoustic Microscope, Amit K. Som, Leonard J. Bond, Kevin J. Taylor

Review of Progress in Quantitative Nondestructive Evaluation

Solid state bonding is now being used in aircraft fabrication. As a result of this, various groups have considered the destructive examination of such bonds and categorized them in terms of characteristics seen in the examination of micrographic sections [1,2]. A range of studies which employ ultrasonic non-destructive techniques for bond-line characterization have also been undertaken [1,3,4].


Anharmonicity, Piezoelectricity, And Solid State Nonlinearity, M. A. Breazeale Jan 1991

Anharmonicity, Piezoelectricity, And Solid State Nonlinearity, M. A. Breazeale

Review of Progress in Quantitative Nondestructive Evaluation

Last summer I showed that for the pure mode directions the nonlinear terms in the equation describing propagation of ultrasound in a crystalline lattice take the same general form as those describing propagation in a fluid.1 This makes possible the definition of a nonlinearity parameter for solids in analogy with the nonlinearity parameter for liquids and gases. The magnitudes of such nonlinearity parameters were shown to be associated with physical properties of the sample under study. Since one can define nonlinearity parameters in terms of linear combinations of second order elastic (SOE) and third order elastic (TOE) constants, it ...


Acoustic Nonlinearity In Dispersive Solids, John H. Cantrell, William T. Yost Jan 1991

Acoustic Nonlinearity In Dispersive Solids, John H. Cantrell, William T. Yost

Review of Progress in Quantitative Nondestructive Evaluation

It is well known that the interatomic anharmonicity of the propagation medium gives rise to the generation of harmonics of an initially sinusoidal acoustic waveform. It is, perhaps, less well appreciated that the anharmonicity also gives rise to the generation of a static or “dc” component of the propagating waveform. We have previously shown [1,2] that the static component is intrinsically linked to the acoustic (Boussinesq) radiation stress in the material. For nondispersive solids theory predicts that a propagating gated continuous waveform (acoustic toneburst) generates a static displacement pulse having the shape of a right-angled triangle, the slope of ...


Second Order Nonlinearities And Their Application In Nde, Laszlo Adler, Peter B. Nagy Jan 1991

Second Order Nonlinearities And Their Application In Nde, Laszlo Adler, Peter B. Nagy

Review of Progress in Quantitative Nondestructive Evaluation

Although it has been recognized for quite some time that solid materials do not strictly obey Hooke’s law, linear elastic wave studies provided valuable tools to obtain both microscopic and macroscopic material parameters. Ultrasonic wave velocities can be used to obtain second order elastic constants while attenuation measurements can be related to many parameters, e.g. grain size in metals. It is quite recent that the NDE community turned its attention to investigate the possibility of using nonlinear acoustic techniques to measure properties of solids and interfaces [1–8]. The so-called nonlinearity parameter which is the combination of second ...