Coupled strain and temperature gradient analysis in curved surfaces

Abstract

A common method in experimental mechanics is 3D digital image correlation (DIC) for determining deformations of curved surfaces, whereby the motion of material points is measured. The temperatures induced by the deformation of surfaces or by other heat sources are of particular interest as well. In this context, surface temperatures can be measured using infrared thermography systems. However, the disadvantage of this approach is that a thermographic camera only provides the two‐dimensional temperature distribution (plane images) of three‐dimensionally curved surfaces. Thus, the temperature and temperature gradients on the curved surface assigned to material points cannot be specified. However, for particular problems the temperature and the motion of material points are of particular interest. In the literature, planar problems are studied and simplifying assumptions are made so that a simple coupling of thermography and DIC is possible. In contrast, this contribution presents a method where 3D DIC is coupled with thermography in such a way that the temperature, temperature gradient, as well as displacement and strain distributions at material points of curved surfaces can be determined over temporal processes. The method also allows a continuous strain and temperature gradient determination over the entire domain, since a special class of functions named radial basis functions is used for interpolating the measured data.