Experimental Determination of Crack Closure by the Cut Compliance Technique

Schindler, Hans-Jakob

doi:10.1520/stp15757s

Cited by 17 publications

(16 citation statements)

References 11 publications

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“…The cut compliance method described by Prime 13 and Schindler 18 was used to determine the longitudinal residual stress. The cut compliance testing was performed on a specimen identical to those used for the fatigue crack growth testing.…”

Section: Methodsmentioning

confidence: 99%

“…The crack growth rate was characterized experimentally using compact tension specimens loaded with a constant value of the applied stress intensity factor range, Δ K Iapp , in order to highlight the influence of residual stress on fatigue crack propagation. The residual stress field was found using the cut compliance technique developed by Prime 13 and Schindler 18 . The hardness and the microstructure were investigated.…”

Section: Introductionmentioning

confidence: 99%

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Residual stress effects on fatigue crack growth in a Ti‐6Al‐4V friction stir weld

Pasta

Reynolds

2008

Fatigue Fract Eng Mat Struct

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A B S T R A C T Recent studies have illustrated a predominant role of the residual stress on the fatigue crack growth in friction stir welded joints. In this study, the role of the residual stress on the propagation of fatigue cracks orthogonal to the weld direction in a friction stir welded Ti-6Al-4V joint was investigated. A numerical prediction of the fatigue crack growth rate in the presence of the residual stresses was carried out using AFGROW software; reasonable correspondence between the predictions and the experimental results were observed when the effects of residual stress were included in the simulation.Keywords fatigue crack growth propagation; friction stir welding; residual stress; titanium alloy. N O M E N C L A T U R E AFGROW= air force fracture mechanics and fatigue crack growth software CT = compact tension geometry fatigue specimen da/dN = fatigue crack growth rate K Ires = mode I residual stress intensity factor due to weld residual stress MT = middle crack tension geometry fatigue specimen NASGRO = fatigue crack growth model presenting in afgrow database K I = generic mode I stress intensity factor range K Iapp = mode I stress intensity factor range due to applied cyclic load K Ieff = mode I effective stress intensity factor range (above opening load) α = titanium phase having a hexagonal close packed crystal structure β = titanium phase having a body centred cubic crystal structure I N T R O D U C T I O NAt present, fastener technology and fusion welding are widely used to join metallic structures; nevertheless, the manufacturing industries are always under pressure to find new solutions for reduction of assembly costs. However, a significant body of knowledge related to damage tolerance of fastener and fusion welding is in place, and this knowledge base must be developed for new joining technologies before they can be implemented in place of existing methods.In recent years, friction stir welding (FSW) has emerged as an excellent technique for joining aluminium structures. Recent studies 1-6 on fatigue performance of FSW joints have shown that this process is capable of replacCorrespondence: S. Pasta. ing the traditional welding techniques and riveted fastening in some applications. Ericsson et al. 7 found static and dynamic properties of FSW joints better than the MIGpulse and TIG-weld and they achieved fatigue strength comparable with base material. Lomolino et al. 8 presented a statistical analysis of the available data on the fatigue behaviour of friction stir butt-welded Al alloys. In that overview, the endurance fatigue limit for FSW joints was found to approach base material values.Several studies 9-10 were conducted to understand the fatigue crack behaviour of FSW joints in aluminium alloys in the presence of a residual stress field. Bussu and Irving 11 carried out fatigue propagation tests of cracks orthogonal and parallel to the weld centreline in alloy 2024. They showed a significant influence of the residual stress on the fatigue crack growth, while the microstructure and hard...

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Residual stress effects on fatigue crack growth in a Ti‐6Al‐4V friction stir weld

Pasta

Reynolds

2008

Fatigue Fract Eng Mat Struct

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“…Introducing a narrow cut into the closure zone, the residual stress intensity factor is directly provided from the measure of a strain gage in the back-face. Thus the residual stress can be analytically computed by numerical inversion of the appropriate weight function integral equation as described by Schindler (1999).…”

Section: Cut-compliance Methodsmentioning

confidence: 99%

Residual stresses and FCP prediction in FSW through a continuous FE model

Fratini

Macaluso

Pasta

2009

Journal of Materials Processing Technology

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“…An efficient method to determine it experimentally is the cut‐compliance (CC‐) method. For the principle of the method we refer to 9–11 …”

Section: Measurement Of Residual Stressesmentioning

confidence: 99%

“…For the principle of the method we refer to. [9][10][11] In the present case the required strain measurements are performed by a strain gauge (SG)`F' on the top surface of the weld and SG`R' located at the rear surface right at the weld root ( Fig. 6).…”

Section: E a S U R E M E N T O F R E S I D U A L S T R E S S E Smentioning

confidence: 99%

A fracture mechanics approach to estimate the fatigue endurance of welded t‐joints including residual stress effects

Schindler

Martens

Sönnichsen

2006

Fatigue Fract Eng Mat Struct

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A B S T R A C T Residual stresses and weld defects play a major role in the fatigue behaviour of welded structures, so these effects need to be accounted for in a theoretical analysis. A simplified engineering procedure based on linear-elastic fracture mechanics is applied to estimate the fatigue behaviour, particularly the limit of endurance. Local geometrical irregularities and pre-existing flaws, which are typical for this kind of weld, are covered by an overall notch intensity factor instead of a specific stress intensity factor, so the initial flaw size is not needed explicitly in the analysis. The effect of residual stresses can be easily included. The cut-compliance method was applied to measure the residual stress distribution on the cross-section of the weld. A welded T-joint was used as a benchmark. Unexpectedly, compressive residual stresses were found to prevail in the root region. According to the analysis, they contribute to the endurance limit of the considered joint by about 50%. This result was confirmed by fatigue tests where a significant decrease in the fatigue strength after a post-weld stress relieving heat treatment was observed.

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Experimental Determination of Crack Closure by the Cut Compliance Technique

Cited by 17 publications

References 11 publications

Residual stress effects on fatigue crack growth in a Ti‐6Al‐4V friction stir weld

Residual stress effects on fatigue crack growth in a Ti‐6Al‐4V friction stir weld

Residual stresses and FCP prediction in FSW through a continuous FE model

A fracture mechanics approach to estimate the fatigue endurance of welded t‐joints including residual stress effects

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