Using Thermoelastic Stress Analysis to Detect Damaged and Hot Spot Areas in Structural Components

Abstract

This paper discusses the suitability of using TSA (thermoelastic stress analysis) as an advanced tool to detect damaged areas and highly stressed (hot spot) areas in structural components. Such components can be, for example, parts of large structural panels built of welded metallic or composite materials. Besides detecting hot spot areas, it is expected that stresses in these areas can be suitably quantified and processed in order to predict crack initiation and propagation due to in-service loads. The paper starts with references to selected review and application articles on the subject. Two simple laboratory experiments are presented which illustrate the quality of the results that can be achieved using TSA. In the first experiment, a stainless steel T-joint designed to model a welded structural component is analysed. The T-joint had a machine-notched crack-like flaw close to the component's weld toe. The qualitative and quantitative experimental results determined along four specified areas of the T-joint model showed that TSA can indeed be used as a tool to detect loaded cracks and hot spots in large metallic structures, and that stresses can be accurately evaluated. In the second experiment, a prismatic bar made of CFRE (carbon fibre-reinforced-epoxy) was tested to locate three subsurface areas of damage introduced beforehand into the component. Two of these inside damaged areas were detected to be 3.1 mm and 7.1 mm from the observed surface. The positive results achieved with the two lab experiments, along with a review of the selected research publications, indicate that TSA application can be extended to the real-world field of structural components. Topics to be addressed in this research field should have to do with components that work under random or quasi-cyclic service loading, problems where adiabatic conditions do not prevail, and reduction of the cost of infra-red cameras.

Evaluation of Different Non-destructive Testing Methods to Detect Imperfections in Unidirectional Carbon Fiber Composite Ropes

“…The TSA analysis is one typical method applied to polymer composites, including carbon fiber reinforced plastic (CFRP), to detect different kinds of damage, but most sensitive to delaminations [12][13][14]. The reflection or transmission of ultrasonic waves can be used to detect interfaces or heterogeneities in CFRP components [11].…”