Bio: Yih-Hsing Pao is an academic researcher from Cornell University. The author has contributed to research in topics: Wave propagation & Longitudinal wave. The author has an hindex of 17, co-authored 28 publications receiving 1401 citations.
TL;DR: In this paper, the authors analyzed the source of acoustic emission using the generalized ray theory and Cagniard's method and obtained the transient solutions by evaluating the ray integrals with a complex algorithm.
Abstract: To study the mechanism of the source of acoustic emission, we analyze the transient waves which are generated by four kinds of point sources, a single force, double force, and center of dilatation, all inside an infinite plate, and a single force on the surface of the plate. Some of these forces or a combination of them could be used to model the dynamic process of material defects. The analysis is based on the generalized ray theory and Cagniard’s method. Transient solutions are obtained by evaluating the ray integrals with a complex algorithm. Numerical results are shown for receivers that are located at a distance up to six plate thickness, and for a duration less than ten transit time for a P‐wave to cross the thickness of a plate.
TL;DR: In this article, the acoustoelasticity equations of orthotropic elastic solids with initial stresses were formulated in both natural and initial frames of reference and applied to investigate the propagation of ultrasonic waves in orthotropic linear solids.
Abstract: The equations of acoustoelasticity are formulated in both natural and initial frames of reference and applied to investigate the propagation of ultrasonic waves in orthotropic elastic solids with initial stresses. The foundation of the equations is re‐examined for the purpose of applying them to the measurement of residual stresses.
01 Aug 2014
TL;DR: In this article, a comparison of different shell theories for nonlinear vibrations and stability of circular cylindrical shells is presented. But the authors do not consider the effect of boundary conditions on the large-amplitude vibrations of circular cylinders.
Abstract: Introduction. 1. Nonlinear theories of elasticity of plates and shells 2. Nonlinear theories of doubly curved shells for conventional and advanced materials 3. Introduction to nonlinear dynamics 4. Vibrations of rectangular plates 5. Vibrations of empty and fluid-filled circular cylindrical 6. Reduced order models: proper orthogonal decomposition and nonlinear normal modes 7. Comparison of different shell theories for nonlinear vibrations and stability of circular cylindrical shells 8. Effect of boundary conditions on a large-amplitude vibrations of circular cylindrical shells 9. Vibrations of circular cylindrical panels with different boundary conditions 10. Nonlinear vibrations and stability of doubly-curved shallow-shells: isotropic and laminated materials 11. Meshless discretization of plates and shells of complex shapes by using the R-functions 12. Vibrations of circular plates and rotating disks 13. Nonlinear stability of circular cylindrical shells under static and dynamic axial loads 14. Nonlinear stability and vibrations of circular shells conveying flow 15. Nonlinear supersonic flutter of circular cylindrical shells with imperfections.
TL;DR: In this article, the authors provide a vision of ultrasonic guided wave inspection potential as we move forward into the new millennium and provide a brief description of the sensor and software technology that will make ultrasonic guidance wave inspection commonplace in the next century.
Abstract: Ultrasonic guided wave inspection is expanding rapidly to many different areas of manufacturing and in-service inspection. The purpose of this paper is to provide a vision of ultrasonic guided wave inspection potential aswe move forward into the new millennium. An increased understanding of the basic physics and wave mechanics associated with guided wave inspection has led to an increase in practical nondestructive evaluation and inspection problems. Some fundamental concepts and a number of different applications that are currently being considered will be presented in the paper along with a brief description of the sensor and software technology that will make ultrasonic guided wave inspection commonplace in the next century.
TL;DR: Sokolnikoff's book as discussed by the authors differs greatly from Southwell, Timoshenko, and Love in spirit and content, and is symptomatic of the change in outlook of American mathematics over the past few decades.
Abstract: THE appearance of a treatise in English upon the mathematical theory of elasticity is an event the potential importance of which may be judged by the that the author, in his frequent suggestions for collateral reading, refers to only three such, those of Southwell, Timoshenko, and Love. In spirit and content Sokolnikoff}s book differs greatly from each and all of these. It may be described by a possible sub-title: “A pure mathematician surveys topics related to certain problems in the mathematical theory of elasticity”. It is symptomatic of the change in outlook of American mathematics over the past few decades. Mathematical Theory Of Elasticity Prof. I. S. Sokolnikoff with the collaboration of Asst. Prof. R. D. Speche. Pp. xi + 373. (New York and London: McGraw-Hill Book Co., Inc., 1946.) 22s. 6d.
TL;DR: In this paper, the authors presented experimental evidence for chaotic type non-periodic motions of a deterministic magnetoelastic oscillator, analogous to solutions in non-linear dynamic systems possessing what have been called "strange attractors".
Abstract: Experimental evidence is presented for chaotic type non-periodic motions of a deterministic magnetoelastic oscillator. These motions are analogous to solutions in non-linear dynamic systems possessing what have been called “strange attractors”. In the experiments described below a ferromagnetic beam buckled between two magnets undergoes forced oscillations. Although the applied force is sinusoidal, nevertheless bounded, non-periodic, apparently chaotic motions result due to jumps between two or three stable equilibrium positions. A frequency analysis of the motion shows a broad spectrum of frequencies below the driving frequency. Also the distribution of zero crossing times shows a broad spectrum of times greater than the forcing period. The driving amplitude and frequency parameters required for these non-periodic motions are determined experimentally. A continuum model based on linear elastic and non-linear magnetic forces is developed and it is shown that this can be reduced to a single degree of freedom oscillator which exhibits chaotic solutions very similar to those observed experimentally. Thus, both experimental and theoretical evidence for the existence of a strange attractor in a deterministic dynamical system is presented.
TL;DR: This work presents a design of elastic metamaterial that exhibits multiple resonances in its building blocks and shows two negative dispersion bands, of which one supports only compressional waves and thereby blurs the distinction between a fluid and a solid over a finite frequency regime.
Abstract: The ability to withstand shear is one of the properties that distinguishes a solid from a liquid. The proposal of an elastic metamaterial that in one direction only supports compressional waves, and therefore is fluid-like, and in the other supports compressional as well as shear waves represents a hybrid between fluids and solids that may lead to new applications.