Thermoelasticity for the analysis of crack tip stress fields — a review

Abstract

A comprehensive review is given of methods to determine the stress intensity factor at crack tips using thermoelastic stress analysis. In order to obtain accurate results a number of areas of experimental procedure need to be considered and these are discussed in detail. The paper concludes with a discussion on the future potential of the use oj thermoelasticity for the analysis of cracks.

2198 Al–Li plates joined by Friction Stir Welding: Mechanical and microstructural behavior

“…These techniques are contactless and able to investigate areas rather than just single surface points; analysis of the stress fields around a crack tip is performed starting from 2D images which show the temperature distribution over the sample surface. The more recently developed DeltaTherm system makes possible to actually perform real-time investigation of the crack propagation, based on a much faster data collection [25][26][27][28]. The use of TSA is therefore aimed at tracking the crack initiation and growth in relation to the different areas in which it could take place; areas which are affected in various ways by the weld presence.…”

T-stress determination using thermoelastic stress analysis

“…SIFs determined using TSA are directly obtained from the crack tip stress field rather than being inferred from measurements of the crack length and maximum and minimum loads as in other experimental methods [12]. These characteristics of TSA make it an effective method to be used in fatigue and fracture problems.…”

“…These characteristics of TSA make it an effective method to be used in fatigue and fracture problems. A number of methodologies for calculating the SIF are available and were reviewed by Tomlinson and Olden [12], with further developments since the publication of the review [11,13,14]. However, little research has been published on the use of other parameters to formulate the crack tip stress state using TSA.…”

Crack paths under mixed mode loading

“…When the mixed mode stress field around a fatigue crack is examined, see Figure 2, the temperature data from the elastic field around the crack tip can be used to evaluate the range of both ∆K I and ∆K II . A number of methodologies for calculating the stress intensity factor are available and have been reviewed by Tomlinson and Olden [32] in 1999. More recently, developments have focussed on greater accuracy in the determination of mixed-mode stress intensity factors [33][34][35].…”