Towards the derivation of stress intensity factors by parametric modelling of full-field thermoelastic data

Description/Abstract

Thermoelastic Stress Analysis (TSA) is a well-established full-field technique for
experimental stress analysis that has proved to be extremely effective for studying stress fields in
the vicinity of cracks. Recently, work has focused on the observation that the stress-sum contours
(isopachics) obtained from TSA take the form of a cardioid. Genetic Algorithms (GAs) and
Differential Evolution (DE) have proved successful for accurate parameter estimation of the
cardioids, thus allowing the SIFs to be calculated. Originally, some curve-fits indicated that a pure
cardioid form is inappropriate for the base model, especially for mixed-mode cracks. The deviation
from the cardioid form has been shown to be due to higher-order terms within the stress function.
The objective of the current paper is to use a modified version of the original methodology (that
fitted parameters to a single isopachic) to find the higher-order parameters from the entire data field
obtained from the TSA.