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Full-Text Articles in Engineering Science and Materials

A Model Relating Ultrasonic Scattering Measurements Through Liquid–Solid Interfaces To Unbounded Medium Scattering Amplitudes, R. Bruce Thompson, T. A. Gray Oct 1983

A Model Relating Ultrasonic Scattering Measurements Through Liquid–Solid Interfaces To Unbounded Medium Scattering Amplitudes, R. Bruce Thompson, T. A. Gray

Ames Laboratory Publications

The relationship between scattering data obtained from ultrasonic experiments, in which the waves are excited and detected in a finite measurement geometry, and unbounded medium, farfield scattering amplitudes is considered. For a scatterer in a single fluid medium, a Green’s function approach is used to develop an approximate, but absolute, relationship between these experimental and theoretical cases. Electromechanical reciprocity relationships are then employed to generalize to a two medium case in which the scatterer is located in an elastic solid which, along with the ultrasonic transducer, is immersed in a fluid medium. The case explicitly considered is one in ...


A Machining System For Turning Nonaxisymmetric Surfaces, Spivey Stevens Douglass Aug 1983

A Machining System For Turning Nonaxisymmetric Surfaces, Spivey Stevens Douglass

Doctoral Dissertations

Aspheric reflecting surfaces possessing extremely high surface finish and contour accuracy are often demanded by the optics industry. Such reflectors have also been required in high energy gas laser systems used to trigger thermonuclear reactions in experiments connected with advanced electric power generation.

Historically, production of optical pieces of the quality described required many repetitions of selective hand-lapping, polishing and measuring. In the past ten years production of these pieces has been enhanced by machining with diamond cutting tools on precision numerically controlled (NC) turning machines. These machines are capable of generating axisymmetric surfaces competitive in quality to those produced ...


The Clamping Force Of Heat Shrinkable Fittings, David K. Rehbein, B. J. Skillings, J. F. Smith, Donald O. Thompson Jan 1983

The Clamping Force Of Heat Shrinkable Fittings, David K. Rehbein, B. J. Skillings, J. F. Smith, Donald O. Thompson

Review of Progress in Quantitative Nondestructive Evaluation

A number of alloys exhibit a phenomenon which has come to be known as ‘shape memory’. Without exception these alloys undergo a rather special type of martensitic transformation which results from one or another of the elastic constants1–7 weakening with changing temperature to the point that at the transformation temperature the transforming phase becomes both mechanically and thermodynamically unstable. ‘Shape memory’ is exhibited in the following way. A specimen at a temperature above the martensitic transformation is shaped to some desired form. The specimen is then cooled below its transformation temperature and deformed. Subsequent heating of the specimen through ...


Nondestructive Inspection And Evaluation Of Metal Matrix Composites, J. C. Duke Jr., E. G. Henneke Ii, A. Govada, D. Ulman Jan 1983

Nondestructive Inspection And Evaluation Of Metal Matrix Composites, J. C. Duke Jr., E. G. Henneke Ii, A. Govada, D. Ulman

Review of Progress in Quantitative Nondestructive Evaluation

A review is presented of work performed in our laboratory on the nondestructive inspection of metal matrix composites. In order to obtain damage representative of that which occurs in service, the specimens were mechanically loaded to intermediate load levels below that which causes final, catastrophic failure. Various nondestructive techniques were used both during and after the applied loadings to follow damage initiation and progress.


Wave Scattering By Obstacles In Joined Fluid-Solid Half Spaces, V. V. Varadan, T. A. K. Pillai, V. K. Varadan Jan 1983

Wave Scattering By Obstacles In Joined Fluid-Solid Half Spaces, V. V. Varadan, T. A. K. Pillai, V. K. Varadan

Review of Progress in Quantitative Nondestructive Evaluation

In recent years, attention has shifted from the ultrasonic NDE of bulk flaws to flaws in structural components that involve nearby surfaces. Very often it is convenient to exajnine the part in a water tank, locating the transmitting/receiving transducers in water. This paper is concerned with a theoretical study of a near surface flaw in an immersion tank experiment. The analytical problem to be studied is the scattering of ultrasound by an obstacle that is located near a solid-fluid (water) interface. The distance ‘d’ of the center of the flaw from the interface ranges from ‘a’ to ‘15a’ where ...


Ultrasonic 3-D Reconstruction Of Inclusions In Solids Using The Inverse Born Algorithm, David K. Hsu, James H. Rose, Donald O. Thompson Jan 1983

Ultrasonic 3-D Reconstruction Of Inclusions In Solids Using The Inverse Born Algorithm, David K. Hsu, James H. Rose, Donald O. Thompson

Review of Progress in Quantitative Nondestructive Evaluation

Considerable progress has been made in recent years in the development of signal processing algorithms for use in ultrasonic non-destructive evaluation which yield the size, shape, and orientation of a flaw. This kind of flaw information is necessary in order that failure predictions of materials and components can be made from non-destructive tests. The signal processing algorithms that have been developed for ultrasonics are based upon both direct and inverse approximate solutions to the elastic wave scattering problem, and cover various ranges of the parameter ka where k=2π/λ is the wave number of the ultrasound and a is ...


Comparison Of Matrix Methods For Elastic Wave Scattering Problems, S. J. Tsao, V. V. Varadan, V. K. Varadan Jan 1983

Comparison Of Matrix Methods For Elastic Wave Scattering Problems, S. J. Tsao, V. V. Varadan, V. K. Varadan

Review of Progress in Quantitative Nondestructive Evaluation

In the last ten years several numerical methods have been developed for the solution of elastic wave scattering problems that have found application in quantitative flaw definition. Before the development of these methods, due to the complexity of Navier’s equation which governs wave motion in an elastic continuum, numerical results were available only for circular cylinders and spheres. The elastic wave equation is separable only in polar and spherical coordinates. For other geometries, three types of numerical methods have been developed. They were all originally developed for acoustic and electromagnetic problems governed by the scalar and vector wave equations ...


The Transmission/Scattering Of Elastic Waves By A Simple Inhomogeneity—A Comparison Of Theories, Y. C. Sheu, L. S. Fu Jan 1983

The Transmission/Scattering Of Elastic Waves By A Simple Inhomogeneity—A Comparison Of Theories, Y. C. Sheu, L. S. Fu

Review of Progress in Quantitative Nondestructive Evaluation

The method of equivalent inclusion, originally developed by Eshelby1,2 was first applied to study dynamic behavior of composite laminates by Wheeler and Mura3 where they neglected the presence of the mass density mismatch. Fu4,5 gave a similar formulation for the problem of a pair of ellipsoidal inhomogeneities embedded in an infinite elastic medium subjected to time-harmonic waves. A complete formulation and presentation of analytic and numerical results for a single ellipsoidal inhomogeneity are subsequently given by Fu6 following his work on the ultrasonic determination of fracture toughness, References (7) and (8). The eigenstrain approach is employed and the ...


Nde Curricula Needs As Driven By Recent Technological Advances, R. Bruce Thompson Jan 1983

Nde Curricula Needs As Driven By Recent Technological Advances, R. Bruce Thompson

Center for Nondestructive Evaluation Publications

During the last decade, major changes have been occurring in the NDE industry. Driven by advances in structural design, maintenance, and life extension practices, a new emphasis on the quantitative interpretation of nondestructive measurements has emerged (1-3). It is no longer practical to overdesign a system to accommodate the wide range of flaw sizes that might be accepted by a qualitative inspection. Instead, the cost, safety, and performance requirements of many major systems can only be attained by maximizing (and specifying) the reliability of flaw detection, by making quantitative estimates of the sizes of the detected flaws, and by measuring ...


Forward (From "Nde Education/Training For Engineers"), Donald O. Thompson, William F. Riley Jan 1983

Forward (From "Nde Education/Training For Engineers"), Donald O. Thompson, William F. Riley

Center for Nondestructive Evaluation Publications

In 1980 the Materials and Fabrication Committee of the American Society of Engineers, Pressure Vessel and Piping Division, conducted a symposium entitled, "Critical Issues in Materials and Mechanical Engineering" (1). The purpose of this symposium was to identify those engineering issues which affect the future of ASME and the public at large. One of the critical issues defined and unanimously endorsed by this symposium was the reliability of nondestructive evaluation (NDE). In his statement of the issue, Mordfin pointed out that " ... reliable NDE, performed during fabrication and in service, can enhance safety, increase durability, improve performance, and reduce life cycle ...


Educational Opportunities For Nde At Universities, H. J. Weiss Jan 1983

Educational Opportunities For Nde At Universities, H. J. Weiss

Center for Nondestructive Evaluation Publications

We begin with the premise that, unfortunately, there exists a gap between the actual and perceived needs of industry for NDE, and the research and education in NDE at the university level. We would hope to help bridge this gap by appropriate communications between the two sectors, which is one of the reasons for these sessions today. Part of the information of importance to industry is what opportunities currently exist at the university level for educating engineers who will be prepared to make significant contributions to advances in NDE technology. Or, if such university programs do not now exist, what ...