Assessment of effective stress intensity factors using thermoelastic stress analysis

Díaz, Francisco; Patterson, E. A.; Yates, J. R.

doi:10.1243/03093247jsa515

Cited by 12 publications

(5 citation statements)

References 22 publications

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“…Studies have also been done to examine the influence of crack closure and residual stress on the thermoelastic response of a crack. The effects are noticeable 25 and support conclusions that the SIF deduced from TSA is the effective value (DK eff ), 30 which reflects the actual rather than nominal driving force for crack growth. The distinction was illustrated in Diaz et al, 26 where SIF measurements furnished by TSA matched theoretical values only once the latter were corrected for the influence of closure and residual stress.…”

Section: Rajic and Stevesupporting

confidence: 64%

Thermoelastic stress analysis and structural health monitoring: An emerging nexus

Rajic

Galea

2014

Structural Health Monitoring

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Recent innovations in thermal-detector technology are shown to foster the development of an in situ structural health monitoring capability based on thermoelastic stress analysis, a powerful full-field stress-measurement technique that offers an attractive set of diagnostic and prognostic capabilities, some of which are not found in any of the established structural health monitoring modalities. After reviewing these capabilities, the article examines an experimental case study involving the monitoring of an F/A-18 airframe structure subject to full-scale fatigue testing under representative flight spectrum loading spanning nearly one aircraft life time. The case study confirms the viability of the concept and also highlights some of its primary limitations.

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Section: Rajic and Stevesupporting

confidence: 64%

Thermoelastic stress analysis and structural health monitoring: An emerging nexus

Rajic

Galea

2014

Structural Health Monitoring

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“…Previous studies 42,45 have shown that frictional heating of the crack flanks is readily detectable by TSA and it is apparent in Fig. 5c, e, g and h as very small bright horizontal lines extending radially, to the left, from the hole.…”

Section: Resultsmentioning

confidence: 53%

Analysis of the effects of cold expansion of holes using thermoelasticity and image correlation

Bäckman

Cowal

Patterson

2010

Fatigue Fract Eng Mat Struct

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A B S T R A C T Although cold expansion has been shown to have a positive effect on fatigue life, little work to date has been performed to evaluate the evolution of the strain field surrounding the crack tip on the mandrel entry and exit faces in cold-expanded coupons. Full-field strain measurements using both digital image correlation (DIC) and thermoelastic stress analysis (TSA) were used to compare the strains during crack growth around holes that had and had not been cold-expanded by 4%. Simple rectangular fatigue coupons were machined from 2024-T3 aluminium sheet, half had simple open, unexpanded holes and half had cold-expanded open holes. A DIC system was used to monitor the (mandrel) entry face of the coupon while a TSA system was used to monitor the (mandrel) exit face of the coupon during cyclic tensile loading (R-ratio = 0.1). These two systems provide the first published measurements of the simultaneous mandrel entry and exit surface strains surrounding a crack initiating from a cold-expanded hole. The cracks originating from the unexpanded hole exhibit a strain field around the crack tip which is characteristic of a mode I fatigue crack while those emanating from the cold-expanded holes show a significantly lower distribution of strains around the crack tip. Crack opening displacements evaluated from the strain data obtained from DIC, are substantially reduced by the residual compressive stresses from cold expansion, while the overall fatigue data show the life improvement achieved at various applied stress levels.

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“…Indeed, the literature is full of examples of highly successful practical applications (e.g. [10][11][12]). …”

Section: Thermoelasticitymentioning

confidence: 99%

Thermoelastic stress analysis with a compact low-cost microbolometer system

Rajic

Rowlands

2013

Quantitative InfraRed Thermography Journal

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This article describes the development and validation of a novel thermoelastic stress analysis (TSA) system based on a low-cost microbolometer device. The use of a microbolometer for a highly synchronous and delicate temperature measurement breaks a longstanding and exclusive reliance on high performance, cooled photon detectors for thermoelastic applications. It is shown that despite markedly inferior noise equivalent temperature detectivity and dynamic response specifications, microbolometers are capable of achieving comparable levels of stress measurement performance. The practical implications for experimental stress analysis are significant. Microbolometers are relatively low in capital cost, small in size, have good tolerance to shock and vibration and consume less power than their photon counterparts, attributes that confer enormous practical advantages. It is argued that the emergence of TSA systems that are more affordable and better suited to in-service application could help to promote a much broader use of this powerful technique in applications across the life cycle of high value civil, maritime and aerospace assets, from the validation of finite element modelling for design to in-service structural integrity assessment. A full-scale fatigue test of a flight-critical aircraft structural component is employed as a case study to demonstrate important aspects of the capability. Future directions in the development and application of low-cost miniaturised systems are also discussed.

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Assessment of effective stress intensity factors using thermoelastic stress analysis

Cited by 12 publications

References 22 publications

Thermoelastic stress analysis and structural health monitoring: An emerging nexus

Thermoelastic stress analysis and structural health monitoring: An emerging nexus

Analysis of the effects of cold expansion of holes using thermoelasticity and image correlation

Thermoelastic stress analysis with a compact low-cost microbolometer system

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