Visualization of stress tensors determined by neutron diffraction

Abstract

The concepts and advantages of scientific visualization in the analysis of residual stress are demonstrated, using data obtained from neutron diffraction for a welded component. Because of the discrete nature of the data set, we have used local glyphs to image the stress tensor and its orientation relative to the sample. The traditional stress ellipsoid is the most natural and intuitive glyph which clearly shows the orientation and relative magnitudes of the principal stresses. Colour coding is necessary to convey the maximum possible information, leading to the introduction of the principle–normal–shear (PNS) glyph, in which the orientation of the stress vector is mapped as a colour onto the ellipsoid surface. This indicates, in an intuitive manner, the nature of the traction forces—tensile, compressive and shear—and their orientation in the material. This information can be used in combination with knowledge of the microstructure and loading patterns to identify potential failure modes and locations in the sample.