Determination of Predominantly Mode Ii Stress Intensity Factors From Isochromatic Data

Abstract

A new approach to the solution of stress intensity factors from isochromatic data has been developed and is based on complex Fourier analysis. Solutions are shown to be accurate when the loading of the crack tip is predominantly Mode I1 and also for cases that are generally mixed-mode. The new method and its application to a four-point-bend test is described in this paper. Tests on angled-edge-cracked specimens have also been performed to show the validity of the method for a range of mixed-mode loadings.

Investigation of crack-tip plasticity in high volume fraction particulate metal matrix composites

“…By contrast, because photoelasticity provides only the elastic strain fields in the birefringent coating, it is mainly used to determine experimentally stress intensity factors for complex loading modes in components where the fields are predominantly linear elastic [24][25][26][27]. Because constraint effects that arise in elastic-plastic materials are then weak, such experimental data agree reasonably well with theoretical plane-stress solutions.…”

Crack paths under mixed mode loading

“…Several methods have been developed to determine K I and K II using the full field of data surrounding the slit tip [18,19]. Nurse and Patterson [16] also developed a photoelastic method to predict the direction of crack growth using the theory that long cracks usually grow under mode I loading in direction perpendicular to maximum tangential stress.…”

“…Shterenlikht et al [38] developed the method used in photoelasticity by Nurse and Patterson [19] to accurately determine mixed-mode stress intensity factors using full field ESPI and image correlation data. An advantage of these techniques is that minimal specimen preparation is required, only using the painted or abraded surface of the component, unlike reflection photoelasticity and moiré where a coating or grating has to be bonded to the surface.…”

Mid-thickness studies of the stress intensity factor in the bulk of bainitic steel

“…Accordingly, the tool can be used under small scale yielding (SSY) conditions. For other full-field techniques such as thermo-elasticity [3], photo-elasticity [1], digital image correlation [28] or electronic speckle patter interferometry [4], this is achieved by collecting data from outside the plastic zone. This effect is studied here by including and excluding the data from the plastic zone in the data used for estimating the SIF.…”

“…he experimental characterisation of crack tip fields is normally done using surface techniques such as photoelasticity [1], Moiré interferometry [2], thermo-elastic stress analysis [3], electronic speckle pattern interferometry [4] or digital image correlation [5,6]. For thin components, the surface behaviour is normally representative of the T complete behaviour [7].…”