Causes of uncertainty in thermoelasticity measurements of structural elements

Thermoelasticity is a contactless technique for measuring stress distributions in structural elements stressed by dynamic loads. This work describes the characteristics, analyzes the main causes of uncertainty and illustrates a series of operative methods for reducing its effects. More specifically, the effects of the angle of view between the thermographic camera and the surface of the object are studied, along with those due to the heat transmission by conduction between the various parts of the thing being measured as a function of the stress frequencies. The analyses, both theoretical and experimental, are aimed at defining the operational limits and optimal measurement and test conditions in relation to the measurement uncertainty that is considered tolerable in the specific application.