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1996 Contents


ESPI - A VIABLE NDE TOOL FOR PLANT EXTENSION (1996)

ABSTRACT

This paper reports on the ability of ESPI to detect in-plane displacements of a notched specimen, loaded in a 3-point bending method, particularly in the vicinity of the notch tip. Two different types of material were used for the specimens; perspex, a purely elastic material, and aluminium an elastic-plastic material. The results of the fringe pattern analyses were consistent with the expected behaviour of the material concerned from the start of the loading until failure.

The events included necking, ductile tearing and permanent plastic deformation in the aluminium specimens, and brittle fracture in the perspex specimens. The paper also reports on the simulation of the ESPI method through the mechanics of a finite element analysis (FEA) . The calculated fringe patterns can be helpful in the interpretation of the actual patterns obtained during an inspection and thus used to quantify the effects of the flaw. The example given here compares the patterns obtained from a pressure vessel model (cylinder) with axial and circumferential thumbnail cracks, to the patterns calculated using the finite element package ABAQUS.

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INSPECTING GLASSFIBRE REINFORCED PLASTIC PIPING USING PORTABLE ESPI AND SHEAROGRAPHY (1996)

ABSTRACT

This paper demonstrates the non destructive evaluation of selected glassfibre reinforced plastic piping for structural defects. The items selected were constructed from glassfibre and polyester resin and include a tubular elbow, and a hollow cube with pre-manufactured delaminations. By inspecting the objects on non vibration isolating surfaces the paper also investigates the feasibility of a Portable NDT unit capable of performing both Electronic Speckle Pattern Interferometry (ESPI) and Shearography, which are the chosen methods of inspection. The resultant interferograms are presented and their features highlighted. A discussion and interpretation of the fringe patterns supports the detected defect areas. The paper is concluded by comparing the two methods of inspection and discusses their advantages and limitations.

Complete Paper (540kB)