摘要:

The characteristic features of acoustic emission diagnostics of welded joints are given. Methods of deformation identification and fracture stages on the basis of statistical analysis of the average energy and the median frequency of AE signals spectra are considered. The possibility of estimating locality degrees of plastic deformation during the testing of a large-sized tube specimen using statistical parameter - entrophy of the energy spectrum of the AE signals is shown.

ISSN:1058-9759    

DOI:10.1080/02780899708953019

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

This article considers the problem of thickness measurements and flaw detection in concrete with one side access. It can be solved by ultrasonic echo methods based on the application of multiple-unit antenna arrays, with further data processing in accordance with tomographic algorithms. The data processing algorithm and criteria of the selection of antenna arrays parameters, based on experimental investigations, are described in the article. The results of concrete inner structure inspection obtained by the proposed method are presented. Practically, it is possible to receive an image of concrete cross section at depths of up to one meter and to detect hollow defects with diameters of more than 50 mm.

ISSN:1058-9759    

DOI:10.1080/02780899708953020

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

An analysis is given of the problems associated with the design of multiple purpose Robotic NDT systems which are readily transportable between different geographical locations and are able to climb over large areas of vertical walls and ceilings of any material composition to provide access to remote and hazardous environments. The analysis is illustrated by the description of a prototype system, designed in a modular fashion with off-the-shelf components to minimise development and subsequent batch production costs. Essentially the system consists of a pneumatically powered vehicle carrying an anthropomorphic arm i.e. an arm with at least six degrees of freedom that replicates some relevant advantageous characteristics of the human arm. Its performance is illustrated by some indicative trial results using ultrasonic wet and dry contact techniques applied to a simulated wall of a large ferrous oil storage tank containing corrosion thinning defects.

ISSN:1058-9759    

DOI:10.1080/02780899708953021

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The penetration depth into a medium of sagittally polarized Rayleigh waves propagating on a planar stress-free surface of an isotropic medium, has been considered. Using values of the ratio cR/ct(where cRdenotes the velocity of the Rayleigh wave, and ct, the velocity of the transverse sound wave) calculated from the dispersion relation for the Rayleigh surface wave, the penetration depths (kβL)-1and (kβt)-1defined by Maradudin, have been calculated as functions of the ratio CR/CL, (where cLdenotes the speed of the longitudinal acoustic wave), the ratio cR/ctand also of the Poisson's ratio σ. The amplitudes of the components U1and U3of the displacement field for sagittally polarized Rayleigh waves have been calculated as function of the distance x3from the surface, for various values of the Poisson's ratio σ.

ISSN:1058-9759    

DOI:10.1080/02780899708953022

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Ultrasonic longitudinal and shear wave velocities can be evaluated in cylindrical specimens using line contact with transducers. The present communication discusses various important aspects involved in the method regarding time of arrival, phase and height of the echoes.

ISSN:1058-9759    

DOI:10.1080/02780899708953023

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor