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Full-Text Articles in Mechanical Engineering

Structure Evolution And Dielectric Behavior Of Polystyrene-Capped Barium Titanate Nanoparticles, H.Z. Guo, Yaroslav Mudryk, M.I. Ahmad, X.C. Pang, L. Zhao, M. Akinc, Vitalij K. Pecharsky, Nicola Bowler, Z.Q. Lin, Xiaoli Tan Jan 2012

Structure Evolution And Dielectric Behavior Of Polystyrene-Capped Barium Titanate Nanoparticles, H.Z. Guo, Yaroslav Mudryk, M.I. Ahmad, X.C. Pang, L. Zhao, M. Akinc, Vitalij K. Pecharsky, Nicola Bowler, Z.Q. Lin, Xiaoli Tan

Materials Science and Engineering Publications

Polystyrene-capped barium titanate (BaTiO3) nanoparticles with sizes of 11 nm and 27 nm were prepared using amphiphilic star-like diblock copolymer templates. The crystal structure evolution of these nanoparticles over a wide temperature range (10-428 K) was investigated by powder X-ray diffraction. The Rietveld refinement indicates that the abrupt structural transitions observed in micron-sized powders become broad as particle size is reduced to a few tens of nanometers. The orthorhombic phase (Amm2) is observed in the range of 10-388 K, coexisting with the rhombohedral phase (R3c) at lower temperatures and with the tetragonal phase (P4mm) at higher temperatures. At room temperature ...


Experimental Study On Viscosity And Phase Segregation Of Al–Si Powders In Microsemisolid Powder Forming, Yufeng Wu, Iver E. Anderson, Thomas A. Lograsso, Gap-Yong Kim Dec 2009

Experimental Study On Viscosity And Phase Segregation Of Al–Si Powders In Microsemisolid Powder Forming, Yufeng Wu, Iver E. Anderson, Thomas A. Lograsso, Gap-Yong Kim

Mechanical Engineering Publications

Semisolid powder forming is a promising approach for near-net shape forming of features in macro-/microscale. In this paper, viscosity and phase segregation behavior of Al–Si powders in the semisolid state were studied with back extrusion experiments. The effects of process parameters including shear rate, extrusion ratio, heating time, and precompaction pressure were analyzed using the design of experiments method. The results showed that the effects of shear rate, extrusion, ratio and heating time were statistically significant factors influencing the viscosity. The semisolid state powders showed a shear thinning behavior. Moreover, microstructure analysis of extruded parts indicated severe phase ...


Momentum Transfer Between Polydisperse Particles In Dense Granular Flow, D. Gao, R. Fan, Shankar Subramaniam, Rodney O. Fox, David K. Hoffman Apr 2005

Momentum Transfer Between Polydisperse Particles In Dense Granular Flow, D. Gao, R. Fan, Shankar Subramaniam, Rodney O. Fox, David K. Hoffman

Mechanical Engineering Publications

We perform molecular dynamics (MD) simulations (based on the soft-sphere model) of a model dry granular system consisting of two types of spherical particles differing in size and/or density to characterize particle-particle momentum transfer (solid drag). The velocity difference between two types of particles is specified in the initial conditions, and the evolution of relative mean velocity and the velocity fluctuations in terms of granular temperature are quantified. The dependence of the momentum transfer is studied as a function of volume fraction, size and density ratio of the two types of particles, inelasticity, and friction coefficient. An existing continuum ...


Objective Decomposition Of The Stress Tensor In Granular Flows, D. Gao, Shankar Subramaniam, Rodney O. Fox, David K. Hoffman Feb 2005

Objective Decomposition Of The Stress Tensor In Granular Flows, D. Gao, Shankar Subramaniam, Rodney O. Fox, David K. Hoffman

Mechanical Engineering Publications

A model for the stress tensor in granular flows [Volfson, Tsimring, and Aranson, Phys. Rev. Lett. 90, 254301 (2003)] is correctly generalized to an objective form that is independent of the coordinate system. The objective representation correctly models the isotropic and anisotropic parts of the stress tensor, whereas the original model for stress tensor components is dependent on the coordinate system. This general objective form of the model also relaxes the assumption in the original model that the principal axes of the granular stress tensor be coaxial with that of the “fluid” stress tensor. This generalization expands the applicability of ...


Surface Oxidation Of A Quasicrystalline Al–Cu–Fe Alloy: No Effect Of Surface Orientation And Grain Boundaries On The Final State, P. J. Pinhero, James W. Anderegg, D. J. Sordelet, Thomas A. Lograsso, D. W. Delaney, Patricia A. Thiel Aug 1999

Surface Oxidation Of A Quasicrystalline Al–Cu–Fe Alloy: No Effect Of Surface Orientation And Grain Boundaries On The Final State, P. J. Pinhero, James W. Anderegg, D. J. Sordelet, Thomas A. Lograsso, D. W. Delaney, Patricia A. Thiel

Chemistry Publications

We have used x-ray photoelectron spectroscopy and Auger electron spectroscopy to examine the characteristics of oxides on two types of quasicrystalline Al–Cu–Fe samples. One type was formed by consolidation of powders, resulting in multiple grains with random surface orientations. The other was a single grain, oriented to expose a fivefold surface. Both were oxidized to saturation in a variety of environments at room temperature. We measured the elemental constituents that oxidized, the extent of oxygen-induced Al segregation, and the depth of the oxide. Under the conditions of our experiments, there was little, if any, significant difference between the ...


Experiences In The Use Of Guided Ultrasonic Waves To Scan Structures, R. Bruce Thompson Jan 1997

Experiences In The Use Of Guided Ultrasonic Waves To Scan Structures, R. Bruce Thompson

Review of Progress in Quantitative Nondestructive Evaluation

The use of guided ultrasonic waves to rapidly interrogate large structures is a topic that is currently receiving considerable attention. The purpose of this paper, and the companion paper by Alers [1], is to briefly review some past experience that may not be readily available to current researchers since many of the results were not presented in archival publications. The work described in this paper was conducted in the context of exploring applications of electromagnetic-acoustic transducers (EMATs) [2,3] as a part of the NDE effort at the Rockwell International Science Center in the period 1970–1980. In addition to ...


Crack Length Determination By Ultrasonic Methods, David Kent Rehbein, R. Bruce Thompson, Otto Buck Jan 1993

Crack Length Determination By Ultrasonic Methods, David Kent Rehbein, R. Bruce Thompson, Otto Buck

Review of Progress in Quantitative Nondestructive Evaluation

Accurate calculation of the stress intensity factor on a given component under load relies on an accurate size determination of the flaws present in the component. The challenge to the NDE community has been development of reliable techniques to provide that accurate size determination. Many research groups have investigated this problem using ultrasonic methods with summaries of their techniques and results provided by various authors [1–3]. In general, the techniques developed fall into three general categories; (1) determination of crack length from signal amplitude measurements, (2) determination of crack length from time-of-flight measurements, and (3) determination of crack length ...


An Artificial Neutral Network Fault-Diagnostic Adviser For A Nuclear Power Plant With Error Prediction, Keehoon Kim Jan 1992

An Artificial Neutral Network Fault-Diagnostic Adviser For A Nuclear Power Plant With Error Prediction, Keehoon Kim

Retrospective Theses and Dissertations

Since the accidents at the Three-Mile Island (TMI) and m Chernobyl nuclear power plants (NPPs), the safety of NPPs has become an even more important concern to both the nuclear power industry and the general public. The demand for safer plants has ever since. Responding to the demand, many scientists increased have investigated augmenting NPP safety in various ways. For m example, innovative reactor designs, better safety system R designs, human factor studies, stricter safety regulations, and so on, have been developed and implemented in the years since the above-mentioned accidents.


Characterization Of Microstructural Effects On Fatigue Crack Closure, David K. Rehbein, Dan J. Barnard, Otto Buck Jan 1991

Characterization Of Microstructural Effects On Fatigue Crack Closure, David K. Rehbein, Dan J. Barnard, Otto Buck

Review of Progress in Quantitative Nondestructive Evaluation

The growth of a fatigue crack is modified by the development of contacts between the crack faces1,2creating shielding and thus canceling a portion of the applied load. These contacts develop through a number of mechanisms, including plastic deformation, sliding of the faces with respect to each other and the creation and collection of debris such as oxide particles3. Compressive stresses are created on either side of the partially contacting crack faces resulting in opening loads that must be overcome in order to apply a driving force to the crack tip for growth. In this way, the crack tip is ...


Use Of Lamé Mode Properties In The Determination Of Texture Parameters On Al Plates, Y. Li, R. Bruce Thompson, S. J. Wormley Jan 1991

Use Of Lamé Mode Properties In The Determination Of Texture Parameters On Al Plates, Y. Li, R. Bruce Thompson, S. J. Wormley

Review of Progress in Quantitative Nondestructive Evaluation

Texture (preferred grain orientation) characterization of polycrystalline aggregates has traditionally been done by X-ray or neutron diffraction techniques. These techniques are generally slow and destructive. Advances in ultrasonics over the last decade have made it possible to determine texture of cubic polycrystalline aggregates quickly and nondestructively [1–3]. It is known that all polycrystalline materials have some degrees of texture and, when texture is present, the materials are anisotropic, usually weakly orthotropic for rolled plates or sheets. The principle of ultrasonic characterization of texture is to infer texture by sensing and determining the material anisotropy.


Bond Strength Evaluation In Dissimilar Materials, G. C. Ojard, David K. Rehbein, Otto Buck, A. Bevolo Jan 1991

Bond Strength Evaluation In Dissimilar Materials, G. C. Ojard, David K. Rehbein, Otto Buck, A. Bevolo

Review of Progress in Quantitative Nondestructive Evaluation

Diffusion bonding is a useful joining technique that allows similar and dissimilar materials to be bonded together in near net shape. Although modelling of the diffusion bonding process has been done to predict the bonding parameters needed to achieve parent metal mechanical properties (1,2), the possibility still exists that defects will be present in the bonded plane. There are three classes of defects that can be formed, with voids being the most common and heavily studied ones (3–8). Contamination of the bond line is a serious defect and the effect on NDE interrogation has been discussed previously by ...


Ultrasonic Beams With Bessel And Gaussian Profiles, D. K. Hsu, Frank J. Margetan, M. D. Hasselbusch, S. J. Wormley, M. S. Hughes, D. O. Thompson Jan 1990

Ultrasonic Beams With Bessel And Gaussian Profiles, D. K. Hsu, Frank J. Margetan, M. D. Hasselbusch, S. J. Wormley, M. S. Hughes, D. O. Thompson

Review of Progress in Quantitative Nondestructive Evaluation

A novel technique has been developed for generating ultrasonic beams with spatial profiles of amplitude governed by a truncated Bessel function or Gaussian function [1,2]. Bessel beams have very unique properties; in optics Bessel beams have been shown to be diffractionless (J. Durnin et al, 1987 [3,4]). In a related work, R. W. Ziolkowski et al [5] reported experimental measurements of “acoustic directed energy pulse trains” generated by synthetic line array of ultrasonic transmitters in water. However, a Bessel function ultrasonic transducer has never been reported before. Gaussian beams also have desirable properties; they are very easy to ...


Probability Of Tight Crack Detection Via Eddy-Current Inspection, Norio Nakagawa, R. E. Beissner Jan 1990

Probability Of Tight Crack Detection Via Eddy-Current Inspection, Norio Nakagawa, R. E. Beissner

Review of Progress in Quantitative Nondestructive Evaluation

Among current NDE investigations, one of the important topics is the development of so-called probability-of-detection (POD) models. This activity is important because, given a POD model, one can examine inspection systems quantitatively in terms of flaw detectability. In the area of the eddy-current (EC) testing, there are a few applicable POD models in the literature [1,2]. In this paper, we will report on a generalization of the model constructed by one of the present authors [2]. After the generalization is done, the model becomes applicable to a wider variety of flaws than before.


Effects Of Pulse Distortion On Phase Velocity Measurements Using The Zero-Crossing Shift Technique, Y. Li, R. Bruce Thompson Jan 1990

Effects Of Pulse Distortion On Phase Velocity Measurements Using The Zero-Crossing Shift Technique, Y. Li, R. Bruce Thompson

Review of Progress in Quantitative Nondestructive Evaluation

One of the technique that is often used in the measurement of phase velocities of guided elastic modes is the zero-crossing shift technique. Using this technique, one measures time delays (usually through a counter) of a specific zero-crossing for a number of different separation distances of two transducers. The phase velocity Vp is computed as the slope of the distance-delay plot. For non-dispersive waves, this produces no problem as the pulse retains its shape as it propagates.


Strong Scatterers And 1-D Born Inversion, Leonard J. Bond, H. Zhang, James H. Rose Jan 1989

Strong Scatterers And 1-D Born Inversion, Leonard J. Bond, H. Zhang, James H. Rose

Review of Progress in Quantitative Nondestructive Evaluation

Ultrasonic flaw sizing is critical in nondestructive evaluation. However, the data available for sizing are often quite limited. For example, it is common to have a single pulse-echo (back scattered) wavetrain of limited bandwidth: i.e. it contains wavelengths that are comparable to and larger than the dimensions of the flaw. On the other hand a fair amount is often known about the nature of the expected range of flaws. It may be known that the flaw is a void, or a crack or an inclusion of a certain material type. In addition the expected shape for a flaw may ...


Multiviewing Ultrasonic Transducer System For Flaw Reconstruction, David K. Hsu, S. J. Wormley, Donald O. Thompson Jan 1989

Multiviewing Ultrasonic Transducer System For Flaw Reconstruction, David K. Hsu, S. J. Wormley, Donald O. Thompson

Review of Progress in Quantitative Nondestructive Evaluation

The characterization of failure-initiating flaws in materials and components is an important task in the assurance of structural integrity. Based on ultrasonic signals scattered from the flaw in a number of directions, inverse scattering algorithms may be used to reconstruct the size, shape and orientation of the flaw. One of the more successful methods for elastic wave inverse scattering and flaw sizing has been the inverse Born algorithm in the long and intermediate wavelength regime.


Analysis Of A Semi-Automatic System For The Ultrasonic Measurement Of Texture, S. J. Wormley, R. Bruce Thompson, Y. Li Jan 1988

Analysis Of A Semi-Automatic System For The Ultrasonic Measurement Of Texture, S. J. Wormley, R. Bruce Thompson, Y. Li

Review of Progress in Quantitative Nondestructive Evaluation

The texture (preferred grain orientation) of rolled metal plates influences a number of important properties. Included are their form-ability into complex shapes such as beverage cans, vehicle bodies, or airframe skins, and their response to static or dynamic loading when the resulting components are placed into service [1–3]. Considerable benefit would be gained from the development of instrumentation which could measure texture in real time for process control applications or which could easily establish the texture of incoming materials or finished components so that their elastic or plastic mechanical properties could be estimated. As an example of the economic ...


Effects Of Imperfect Interfaces On Acoustic Transmission And Diffraction, David K. Rehbein, L. Van Wyk, R. Bruce Thompson, Otto Buck Jan 1988

Effects Of Imperfect Interfaces On Acoustic Transmission And Diffraction, David K. Rehbein, L. Van Wyk, R. Bruce Thompson, Otto Buck

Review of Progress in Quantitative Nondestructive Evaluation

Contact between the surfaces of a fatigue crack is developed by a variety of mechanisms [1,2], including plastic deformation, sliding of the two faces with respect to one another or the collection of debris such as oxide particles [3]. Consequently, certain characteristic effects occur when the crack is illuminated by an elastic wave. When no contacts are present, a singularity exists in the elastodynamic fields at the crack tip, leading to a set of diffracted fields emanating from the tip. The presence of the contacts modifies the tip diffracted fields and allows energy to be directly transmitted through the ...


Ultrasonic Characterization Of Solid-Solid Bonds From Microstructural Changes, James H. Rose Jan 1988

Ultrasonic Characterization Of Solid-Solid Bonds From Microstructural Changes, James H. Rose

Review of Progress in Quantitative Nondestructive Evaluation

In recent years, new methods of bonding solids have been introduced. These methods (e.g., diffusion bonding and pressure welding) can produce very high quality bonds. In favorable cases the strength of the material in the bond is nearly indistinguishable from that of the host. Similarly, metallographic analysis may indicate almost no microstructural change between the host material and the material in the bonding region. Since these bonds can be of such high quality, they are being used for critical joins. Consequently, an urgent need has arisen for reliable nondestructive inspection methods. This paper is concerned with the use of ...


Ultrasonic Nde Techniques For Integrally Fabricated Rotors, T. A. Gray, Frank J. Margetan, R. Bruce Thompson Jan 1988

Ultrasonic Nde Techniques For Integrally Fabricated Rotors, T. A. Gray, Frank J. Margetan, R. Bruce Thompson

Review of Progress in Quantitative Nondestructive Evaluation

Solid-state bonding methods, e.g., diffusion bonding and pressure welding, are becoming common manufacture and repair techniques for gas turbine engine components. Effective NDE inspection techniques are crucial to the utilization of this approach due to the high stresses on the bond plane associated with jet engine operation. Recently we have examined ultrasonic techniques for assessing bond quality including leaky Rayleigh waves and critical angle longitudinal waves[1], for which the illuminating waves are nearly normal to the bond plane, and longitudinal waves at near grazing incidence to the bond[1]. Based upon preliminary theoretical analyses[1,2] of ultrasonic ...


Ultrasonic Methods Of Texture Monitoring For Characterization Of Formability Of Rolled Aluminum Sheet, A. V. Clark, G. V. Blessing, R. Bruce Thompson, J. F. Smith Jan 1988

Ultrasonic Methods Of Texture Monitoring For Characterization Of Formability Of Rolled Aluminum Sheet, A. V. Clark, G. V. Blessing, R. Bruce Thompson, J. F. Smith

Review of Progress in Quantitative Nondestructive Evaluation

Texture (preferred orientation) has a significant influence on the formability of metals. This was shown experimentally for rolled steel sheet by Stickels and Mould [1]. They found a correlation between the in-plane angular variation of r-value and the anisotropy of Young’s modulus, E, as measured by ultrasonics. The r-value is a measure of plastic strain on deep drawing, defined as ϵyy/(∈yy + ∈zz), with ∈yy the in-plane strain and ∈zz the strain in the thickness direction.


Averaging Techniques And Ultrasonic Pole Figures, J. F. Smith, Y. Li, R. Bruce Thompson Jan 1988

Averaging Techniques And Ultrasonic Pole Figures, J. F. Smith, Y. Li, R. Bruce Thompson

Review of Progress in Quantitative Nondestructive Evaluation

There is considerable interest in the evaluation of texture via ultrasonic measurements because of the advantages when compared to evaluation by diffraction techniques. First, ultrasonic measurements are much more rapid and have the potential of being used concurrently while processing. Second, ultrasonic measurements are nondestructive while diffraction techniques require coupons to be cut for samples. Third, ultrasonic measurements, like neutron diffraction, sample the bulk of the test material while, in contrast, x-ray diffraction samples a thin surface layer. The primary disadvantage of ultrasonic measurements is that the textural evaluation must be based on a quite limited amount of data whereas ...


Determining Crack Tip Shielding By Means Of Acoustic Transmission And Diffraction Measurements, Otto Buck, David K. Rehbein, R. Bruce Thompson Jan 1987

Determining Crack Tip Shielding By Means Of Acoustic Transmission And Diffraction Measurements, Otto Buck, David K. Rehbein, R. Bruce Thompson

Review of Progress in Quantitative Nondestructive Evaluation

Asperity contact along the fracture surface of a crack is one of the mechanisms of crack closure. This contact shields the crack tip, in part, from the externally applied driving force on the crack. We have now succeeded in using experimental information, obtained under plane strain conditions from acoustic transmission and diffraction experiments in the closure region [1,2] to determine a stress intensity factor, KI(local), which shields the crack tip below a stress intensity factor KIclosure a t first contact during unloading occurs.


Ultrasonic Nde Of Tubing Pinch Welds, David K. Rehbein, David K. Hsu, R. Bruce Thompson Jan 1987

Ultrasonic Nde Of Tubing Pinch Welds, David K. Rehbein, David K. Hsu, R. Bruce Thompson

Review of Progress in Quantitative Nondestructive Evaluation

Resistance tube closure welds, referred to as pinch welds, are used to reliably seal small stainless steel tubing. The pinch welding process, discussed in detail by Thomas et al [1], involves applying a load to force electrodes together to collapse the tube, sometimes in the presence of confining dies which prevent lateral expansion. Electric current is injected through the electrodes to soften the tube through Joule heating. The resulting hot plastic deformation causes contact and welding of the inner surfaces of the tube.


The Effect Of Nonspherical Pores And Multiple Scattering On The Ultrasonic Characterization Of Porosity, James H. Rose Jan 1987

The Effect Of Nonspherical Pores And Multiple Scattering On The Ultrasonic Characterization Of Porosity, James H. Rose

Review of Progress in Quantitative Nondestructive Evaluation

Recently, several papers have dealt with the use of the frequency dependent ultrasonic attenuation to characterize gas porosity in structural solids such as cast aluminum [1–4]. The methods proposed provide an estimate of the volume fraction of pores and the average pore size. The estimate of the volume fraction for laboratory samples has been sufficiently accurate that it encourages thoughts of routine industrial use. In the past year, we have considered several corrections which may be of use in transferring the laboratory methods to industrial samples. Three corrections have been developed. The first is a simple way of accounting ...


Ultrasonic Reflection From Rough Surfaces In Water, James H. Rose, David K. Hsu Jan 1987

Ultrasonic Reflection From Rough Surfaces In Water, James H. Rose, David K. Hsu

Review of Progress in Quantitative Nondestructive Evaluation

The use of ultrasound for immersion mode quantitative nondestructive evaluation depends on our ability to model the interaction of the incident beam with the water-solid interface. The effects of surface roughness on the inspection process may be crucial. For example, ultrasonic images of interior flaws will be degraded due to the random fluctuations in the wave front of the incident field [1,2]. Similarly, surface roughness also affects the characterization of porosity in solids from the ultrasonic attenuation [3] since the attenuation is commonly determined by comparing the reflection from the backsurface with that from the front surface of the ...


The Use Of Ultrasonics For Texture Monitoring In Aluminum Alloys, A. V. Clark Jr., A. Govada, R. Bruce Thompson, J. F. Smith, G. V. Blessing, P. P. Delsanto, R. B. Mignogna Jan 1987

The Use Of Ultrasonics For Texture Monitoring In Aluminum Alloys, A. V. Clark Jr., A. Govada, R. Bruce Thompson, J. F. Smith, G. V. Blessing, P. P. Delsanto, R. B. Mignogna

Review of Progress in Quantitative Nondestructive Evaluation

Many alloys of common metals (such as aluminum and steel) are polycrystalline aggregates having preferred orientation (texture) of the single crystals making up the aggregate. Texture often affects mechanical properties, such as response of material to deep drawing which occurs in the manufacture of aluminum cans.


Influence Of Plate Wave Characteristics On The Angular Dependence Of Ultrasonic Velocities, R. Bruce Thompson, J. F. Smith, S. S. Lee Jan 1987

Influence Of Plate Wave Characteristics On The Angular Dependence Of Ultrasonic Velocities, R. Bruce Thompson, J. F. Smith, S. S. Lee

Review of Progress in Quantitative Nondestructive Evaluation

The angular dependence of the velocities of ultrasonic plane waves in a stressed, orthorhombic (orthotropic) continuum has recently been analyzed, and the results have been used to define scenarios for nondestructively measuring stress and preferred grain orientation [1,2]. These techniques make use of particular features which allow the two sources of anisotropy, stress and texture, to be separately determined. However, experimental realization of these ideas involves measurements at surfaces, and the influence of the surfaces on the plane wave solution must be considered. This paper treats the case of an orthorhombic plate, thin with respect to a wavelength. Discussions ...


Technique For Generation Of Unipolar Ultrasonic Pulses, Donald O. Thompson, David K. Hsu Jan 1987

Technique For Generation Of Unipolar Ultrasonic Pulses, Donald O. Thompson, David K. Hsu

Review of Progress in Quantitative Nondestructive Evaluation

Substantial progress has been made in recent years in the development of inverse elastic wave scattering theories for use in ultrasonic nondestructive evaluation (NDE). These include theories that are applicable in different ultrasonic frequency ranges and include formulations in various approximations [1–15]. It is by application of these inverse scattering solutions to ultrasonic inspection results that quantitative measures of the size, shape, and orientation of a flaw can be determined.


Ultrasonic Nde Of Integrally Fabricated Turbine Rotors, T. A. Gray, R. Bruce Thompson, Frank J. Margetan Jan 1987

Ultrasonic Nde Of Integrally Fabricated Turbine Rotors, T. A. Gray, R. Bruce Thompson, Frank J. Margetan

Review of Progress in Quantitative Nondestructive Evaluation

A new challenge to ultrasonic inspection techniques is the NDE of integrally fabricated turbine rotors, where the turbine blades are either bonded to the disk in the manufacturing process or during rotor repair. Although reliable detection of gross defects, such as significant disbanded areas, is certainly essential in bond NDE, this project is primarily concerned with the detection and characterization of overall bond quality from a microstructure perspective. Thus, recent efforts have been directed toward seeking various ultrasonic inspection techniques which show reliable and measurable correlation to near-bond microstructure variations and which are implementable as practical inspection configurations. Experiments have ...