ABSTRACT

Moiré photography [1,2] is a powerful technique for examining the full-field deformation behaviour of both large civil engineering structures, such as buildings and bridges and small components. It is based on applying a regular pattern to the surface and taking photographs with a specially modified camera whilst the structure undergoes a deformation process. One particular feature of the technique is a method for preparing a pattern that can withstand heating. A suspension in alcohol of titanium dioxide pigment is sprayed through a very thin metal mesh lightly attached to the component’s surface. When the mesh is removed, what remains is an array of dots of pure pigment which retains its white opacity at temperatures in excess of 1300 °C. This allows the study of thermal and mechanical behaviour to be carried out in oxidizing environments [2,3] and the approach is especially useful where the levels of anticipated strain are relatively high, for example at the weld interface of two materials with different expansion coefficients.