The theory of thermoelastic stress analysis is reviewed and the implications of some theoretical developments are assessed. Available instrumentation is described and techniques available for separation of individual stress values are summarized. The scope of the technique is illustrated with reference to a number of applications covering crack-tip stress studies, stress analysis and damage assessment in composite materials, and ‘field’ work on a traffic-loaded road bridge.

Development and applications of thermoelastic stress analysis

The application of the thermoelastic technique (SPATE) to two different composite material specimens is described and the results are critically discussed. The relevant theory, which permits a quantitative interpretation of the thermoelastic response from orthotropic materials, is outlined.

The application of thermoelastic stress analysis techniques to composite materials

Quantitative Thermographic Methodology for fatigue assessment and stress measurement

In this chapter an outline of the theoretical foundations for the experimental technique of thermoelastic stress analysis is presented, followed by a description of the equipment, test materials, and methods required to perform an analysis. Thermoelastic stress analysis is a technique by which maps of a linear combination of the in-plane surface stresses of a component are obtained by measuring the surface temperature changes induced by time-varying stress/strain distributions using a sensitive infrared detector. Experimental considerations relating to issues such as shielding from background radiation, edge effects, motion compensation, detector setup, calibration, and data interpretation are discussed. The potential of the technique is illustrated using a number of examples that involve isotropic as well as orthotropic materials, fracture mechanics, separation of component stresses, and vibration analysis. Applications of the method to situations involving residual stresses, elevated temperatures, and variable amplitude loading are also considered.

Thermoelastic Stress Analysis

In thermoelastic stress analysis (TSA) it is normal practice to coat metallic specimens with black paint to enhance and standardize the surface emissivity. It is assumed that the paint coating has no effect on the thermal emission from the specimen, but it is well known that the response is sensitive to paint coating thickness, particularly at higher frequencies. In this paper the effects of loading frequency and paint coating thickness on the thermoelastic response are investigated. The thermoelastic response is compared to theory, and optimum test conditions and coating characteristics are suggested. The motivation for the work is to develop a TSA-based means of residual stress assessment, where the measurement of much smaller temperature changes than those that are resolved in standard TSA is required; therefore the analysis is much more sensitive to the effects of the paint coating. However, the work presented in this paper is relevant to a wide range of TSA investigations and presents data that will be of interest to all practitioners of TSA.

https://iopscience.iop.org/article/10.1088/0957-0233/21/8/085502/pdf

Paint coating characterization for thermoelastic stress analysis of metallic materials

In this paper, a new experimental, computercontrolled, stress-analysis technique (SPATE) based on the measurement of infrared emissions from the surface of a cyclically loaded body, has been used to study the stress distributions in rectangular steel plates and circular rings under cyclic in-plane loading A typical test procedure for quantitative stress measurement is described The effects of surface obliquity and the thickness of the paint coating applied to the specimen surface on the received signal are described and discussed Results are given for three series of test specimens and compared quantitatively with relevant theoretical solutions Attention is drawn to the changes in the received signal as the applied load range increases beyond the elastic limit of the material A new application of the technique to the determination of the stress-intensity factor in acracked body is also illustrated

W. K. Chan

Papers

‘SPATE’ stress studies of plates and rings under in-plane loading