Thermal NDE of Nonplanar Surfaces

Abstract

Thermal inspection of nonplanar surfaces is a subject of interest since many components susceptible to be inspected by TNDE are of complex geometries. Such components can be divided roughly into two categories: approximately planar; and nonplanar. Obviously, the dividing line between these two categories is not clear (Duda et al. 1979). An arbitrary criterion is for instance that for all the points on the inspected surface, the normal to the surface is contained in an angle

$$ \pm 3dBof90^\circ $$

(10.1)

This restricts the cosine of the normal to the [0.75, 1] interval (this hypothesis, as we will see below, allows some practical assumptions). In fact the distinction between planar and nonplanar samples is relevant since, for approximately planar components, TNDE methods studied in the other chapters of this book can be applied without much difficulty.