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Author

Chien-Ching Ma

Other affiliations: Brown University
Bio: Chien-Ching Ma is an academic researcher from National Taiwan University. The author has contributed to research in topics: Normal mode & Vibration. The author has an hindex of 23, co-authored 215 publications receiving 2323 citations. Previous affiliations of Chien-Ching Ma include Brown University.


Papers
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TL;DR: In this paper, a linear coordinate transformation is introduced to simplify the problem of heat conduction in anisotropic multi-layered media, which reduces the presence of many material constants and the complex form of the governing partial differential equation.

80 citations

Journal ArticleDOI
TL;DR: A three-dimensional vibrating block that couples the out-of-plane and in-plane motions is investigated using the amplitude-fluctuation ESPI (AF-ESPI), which demonstrates the advantages of combining high processing speed with high fringe sensitivity.
Abstract: Electronic speckle pattern interferometry (ESPI) is a powerful tool for the full-field measurement of a deformed body. In this paper, a three-dimensional vibrating block that couples the out-of-plane and in-plane motions is investigated using the amplitude-fluctuation ESPI (AF-ESPI). This method demonstrates the advantages of combining high processing speed, such as in the subtraction method, with high fringe sensitivity, such as in the time-averaged method. The optical system for AF-ESPI is then employed to analyze the volume vibration of piezoelectric material for a rectangular parallelepiped configuration. Based on the fact that fringe patterns measured by the AF-ESPI method appear as a clear picture only at the resonant frequency, both the natural frequencies and the out-of-plane and in-plane vibration mode shapes are successfully obtained in this study. Finally, the impedance analysis as well as the finite element method (FEM) with three-dimensional model are also conducted to compare with the result obtained by AF-ESPI. It is shown that the numerical calculation and the experimental result agree fairly well for both the resonant frequency and the mode shape in three-dimensional configurations.

72 citations

Journal ArticleDOI
TL;DR: It is shown that the finite element method (FEM) calculations and the experimental results agree fairly well for the resonant frequencies and mode shapes for piesoceramic disks with free-boundary conditions.
Abstract: Based on the electroelastic theory for piezoelectric plates, the vibration characteristics of piezoceramic disks with free-boundary conditions are investigated in this work by theoretical analysis, numerical simulation, and experimental measurement. The resonance of thin piezoceramic disks is classified into three types of vibration modes: transverse, tangential, and radial extensional modes. All of these modes are investigated in detail. Two optical techniques, amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI) and laser Doppler vibrometer (LDV), are used to validate the theoretical analysis. Because the clear fringe patterns are shown only at resonant frequencies, both the resonant frequencies and the corresponding mode shapes are obtained experimentally at the same time by the proposed AF-ESPI method. Good quality of the interferometric fringe patterns for both the transverse and extensional vibration mode shapes are demonstrated. The resonant frequencies of the piezoceramic disk also are measured by the conventional impedance analysis. Both theoretical and experimental results indicate that the transverse and tangential vibration modes cannot be measured by the impedance analysis, and only the resonant frequencies of extensional vibration modes can be obtained. Numerical calculations based on the finite element method also are performed, and the results are compared with the theoretical analysis and experimental measurements. It is shown that the finite element method (FEM) calculations and the experimental results agree fairly well for the resonant frequencies and mode shapes. The resonant frequencies and mode shapes predicted by theoretical analysis and calculated by finite element method are in good agreement, and the difference of resonant frequencies for both results with the thickness-to-diameter (h/D) ratios, ranging from 0.01 to 0.1, are presented.

53 citations

Journal ArticleDOI
TL;DR: In this paper, the amplitude-e uctuation ESPI (AF-ESPI) method was used to measure the volume vibration of a piezoelectric material for a thick circular disk, a ring, and a thin-walled tube.
Abstract: Electronicspecklepatterninterferometry (ESPI)isafull-e eld,noncontacttechniqueformeasuringthedeformation of a structure subjected to static loading or, especially, to dynamic vibration. Three-dimensional vibrations of piezoelectric materials with cylindrical surfaces are investigated using the amplitude-e uctuation ESPI (AF-ESPI) method. This method demonstrates the advantages of combining noise reduction, like the subtraction method, and high fringe sensitivity, like the time-averaged method. The optical system for AF-ESPI with two in-plane and one out-of-plane measurements is employed to study the volume vibration of a piezoelectric material for a thick circular disk, a ring, and a thin-walled tube. Because the clear fringe patterns measured by the AF-ESPI method will be shown only at resonant frequencies, both the resonant frequencies and the complete vibration mode shapes in three dimensions are obtained experimentally. Finally, impedance analysis and the e nite element method are also utilized, and the results are compared with the measurements obtained by AF-ESPI. It is shown that the numerical calculations and the experimental results agree fairly well for both the resonant frequencies and the mode shapes in three-dimensional cone gurations.

48 citations


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08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

Journal ArticleDOI
TL;DR: There are several methods for the dispersion of CNTs in the polymer matrix such as solution mixing, melt mixing, electrospinning, in-situ polymerization and chemical functionalization of the carbon nanotubes as discussed by the authors.

1,503 citations

Journal ArticleDOI
TL;DR: In this paper, an overview of the principal deformation mechanisms of ultra-strength materials is presented, and the fundamental defect processes that initiate and sustain plastic flow and fracture are described, as well as the mechanics and physics of both displacive and diffusive mechanisms.

701 citations

Journal ArticleDOI
TL;DR: The basic principles and typical applications of this technique based on grating projected and fringe analysis, which attracts the attention and research effort in the past ten years, has been targeted as main objective to review.

483 citations