NDTnet 1998 Aug, Vol.3 No.8

Abstract

A model has been developed in order to simulate the ultrasonic inspection on steel tubes in the Vallourec control configuration. The model permits to simulate the control of steel tubes showing longitudinal defects located near the internal or external surface of tubes which appear during the rolling process. The main goal of this model is to optimise the inspection control condition (incident angle, frequency..) with the tubes geometry. To detect this kind of defect, the probe is placed in an incident plane perpendicular to the axis line of the tube, and inspects the outer surface.

Figure: Divergence of a parallel beam after reflection the internal surface of the tube.

This model is an extension of a model developed in the C.E.A for plane geometries. The main characteristics of this model is to assume that the field radiated in the material doesn't depend on the probe's position. This assumption permits to treat separately the field refracted in the material and the interaction between the defect and the ultrasonic beam. The focal plane is located in the material, so the plane waves approximation is applied where the waves front are assumed plane and parallel. The refracted field is described by the product of the spatial amplitude an temporal distribution. The amplitude spatial distribution is approached by the Rayleigh integral formalism. The beam defect interaction is treated by means of the Kirchhoff theory applied to the elastodynamics. The parallel refracted beam becomes divergent after reflection on the internal surface of tube. To treat the beam divergence, an amplitude weighting coefficient is then calculated by means of the energy conservation of a tube of rays before and after reflection, following the Snell laws.

This model can predict the edge diffraction echoes, the echoes issued to the comer effect, and also the mode conversion echoes. It has been validated on artificial notches, and onsome natural defects. A comparison betweenexperimental and modelling results shows agood agreement and permits to understand thephysical phenomena which explain results.

Abstract Source:
Book of Abstracts, 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN: 87-986898-0-00

Full-Text Source:
Proceedings of the 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN:

Publication Contact:
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