摘要:

This work describes the main outcomes of a cycle of research work in collaboration with the air and space industries and directed to developing new methods and tools for ultrasonic thickness measuring and flaw detection of polymeric composite materials using the optimum filtration of complex modulated signals.

ISSN:1058-9759    

DOI:10.1080/10589750008952878

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The algebraical tomographic reconstruction algorithm of the stress tensor field for the inhomogeneous stress-strain state is presented. This problem is more complicated than traditional scalar fields tomography and it has not been solved yet.The phenomenological linear dependences between relative variation of velocity of ultrasonic shear-waves and stress tensor components in the case of small effects of acoustic elasticity have been chosen as initial correlations. Finally, the determination of spatial distribution of the stress tensor field for inhomogeneous stress-strain state is reduced to a solution of linear algebraical equations for the stress tensor components in each cell. The important advantage of the presented algorithm is its simplicity of its application.

ISSN:1058-9759    

DOI:10.1080/10589750008952879

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Porosity, microcracks, or secondary phase inclusions alter the sound velocities of materials, Ultrasonic scattering at grain and phase boundaries in polycrystalline, multi-phase, or porous media causes attenuation of sound waves and dispersive sound velocities. These effects and also the amplitudes of the scattered waves can be exploited for materials characterization if their dependence on the structure properties is known quantitatively. In this paper the usefulness of sound velocity, attenuation, and backscattering measurements to detect and value damage in steel e.g caused by hydrogen attack is discussed. Numerical evaluations of theoretical results and experimental investigations are presented. It turns out that in most cases velocity measurements do not yield sufficient quantitative information about damage because the variations in sound velocity caused by slight differences of the undamaged material are often larger than those caused by damage. Sound attenuation and back scattering amplitude measurements are more appropriate to estimate damage in steel.

ISSN:1058-9759    

DOI:10.1080/10589750008952880

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

This paper is concerned with the development of a technique for long-range ultrasonic nondestructive inspection of composite tubulars. A dry-contact piezoelectric transducer is used to excite Lamb waves in the axial direction. The field scattered by a defect and/or the mode shape distortion caused by the defect is measured by the use of a laser vibrometer. The presence of the defect is indicated by anomalies in the scattered field. The technique was tested on glass/epoxy composite tubes. It is shown that the presence of a defect (for example, a delamination of I ern diameter) can be remotely detected as far away as one meter from the transmitter, and its position can be located with an accuracy of a few centimeters.

ISSN:1058-9759    

DOI:10.1080/10589750008952881

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor