On the fatigue behavior of cold expanded fastener holes subjected to bolt tightening

Chakherlou, T.N.; Alvandi-Tabrizi, Y.; Kiani, Ali

doi:10.1016/j.ijfatigue.2010.12.014

Cited by 53 publications

(26 citation statements)

References 38 publications

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“…On the other hand, to obtain residual stress, pre-stress and strain distributions created by cold expansion and bolt clamping forces, and also the stress and strain distributions under cyclic loadings, threedimensional finite element models have been employed to predict the fatigue crack initiation life. Results show that there is a good agreement between numerical and experimental results of fatigue, where compared to that of the plain hole specimens, life percentages of bolt treated samples increase considerably [66,67].…”

Section: Introductionmentioning

confidence: 55%

“…How these stresses can withstand external loads is still a question. The majority of research so far suggests that fatigue life modeling and predictions for critical airframes containing cold expanded holes rely on precise determination of initial and current distributions of the residual stresses during cyclic loading [3,8,39,43,66,[68][69][70][71][72]74]. The stability of the initial distribution is of prime importance.…”

Section: Resultsmentioning

confidence: 99%

“…Extensive literature so far covers so many results of several reports particularly on the relaxation of residual stresses at cold expanded holes, where always the decay in stress has been attributed to micro-plasticity or sometimes cracking about the hole [8,66,72,74]. From the point of micro-plasticity, cyclic hardening and softening in precipitation-hardened aluminum alloys is mostly promoted by a mechanism in which the precipitate geometry and distribution as well as dislocation-particle interactions can be altered by cyclic straining.…”

Section: Redistribution Of Residual Stress Fields During Fatiguementioning

confidence: 99%

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Experimental assessment of the redistribution of 3-D residual stresses during early fatigue at split-sleeve cold expanded reamed A/C fastener holes

Özdemir

2017

Scientia Iranica

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Abstract.Cold expansion is an effective technique of inducing favorable compressive residual stresses around fastener holes essentially vital for improving fatigue performances of aircrafts. The benefit is caused by the magnitude and distribution of the compressive stress field. Stress gradients are entirely contingent on type of the cold expansion, local geometry of the hole and characteristics of the metallic structure. During cyclic loading however, initial residual stresses do not remain stable. In the present work, specimens with 4% split-sleeve cold expanded and reamed holes were cycled at the fatigue limit for short periods. Recent method of Combined Step Drilling-Fourier Series Solution 'ATÖzdemir Method' was employed to appraise the continual redistributions of residual hoop stresses at the side of the hole subjected to cyclic load. Some results were compared with that of diffraction methods and Artificial Neural Network (ANN) modeling where, close similarities in stress distributions were confirmed. It is clear that during early fatigue, material nearby the hole is dynamically hardening; in response compressive residual stresses along the bore are gradually increasing till the onset of cracking. Short fatigue cracks mostly initiate from the mandrel entrance side, where subsequently residual hoop stresses begin to relax considerably.

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Section: Introductionmentioning

confidence: 55%

Section: Resultsmentioning

confidence: 99%

Section: Redistribution Of Residual Stress Fields During Fatiguementioning

confidence: 99%

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Experimental assessment of the redistribution of 3-D residual stresses during early fatigue at split-sleeve cold expanded reamed A/C fastener holes

Özdemir

2017

Scientia Iranica

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“…17,21 However, the circumferential residual stress distributions on the middle plane (see Figure 11(b)) of all the CE specimens (C, non-C, BC, and non-BC) are similar. This indicates that the residual stress distribution in the middle region of the hole edge is mainly determined by cold expansion rather than chamfering or bolt clamping.…”

Section: Evaluation Of Residual Stress Distributionmentioning

confidence: 93%

Effects of chamfering, cold expansion, bolt clamping, and their combinations on fatigue life of aluminum–lithium alloy single plate

Huang

Guan

et al. 2018

Advances in Mechanical Engineering

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The objective of this study was to establish the effects of cold expansion, chamfering, bolt clamping, and their combinations on the fatigue life of an aluminum-lithium alloy single plate. Fatigue tests were conducted to quantify the antifatigue effects of the different techniques. A scanning electron microscope was used to perform fracture analyses of the used specimens, and the residual stresses were measured using an X-ray diffraction device. In addition, threedimensional finite element models of the specimens were established and used to characterize their stress states, and the Smith-Watson-Topper method was used to predict the fatigue lives of the specimens. The fatigue test results showed that all the considered processes improved the fatigue life of the pristine specimen. The most effective was a combination of 3.2% cold expansion, 1-mm chamfering, and bolt clamping using a 6.4-N m torque, which improved the fatigue life of the pristine specimen by a factor of 15.5. The finite element method results also revealed that this combination decreased the maximum stress and confirmed its superiority in relation to the other fatigue-life enhancement techniques in terms of the anti-fatigue effect. The Smith-Watson-Topper method underestimated the specimen fatigue life, but the accuracy satisfied engineering requirements.

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“…Chakherlou at al. [9] perform 3D numerical analyses using conical mandrels. Ismonov et al [10], whereas, simulate the mandrels reproducing the real geometry.…”

Section: Introductionmentioning

confidence: 99%

Effect of the indentation process on fatigue life of drilled specimens

et al. 2015

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Design and manufacture of mechanical elements are strongly influenced by the evaluation of the residual stresses due to their effects on the material strength. This paper presents numerical and experimental results performed on AW 6082-T6 aluminum alloy drilled specimens when the hole is created after a bilateral indentation process. The plastic deformation induced by the indenters creates a compressive residual stress field around the hole, which persists after the drilling operation. Several numerical analysis have been carried out in ANSYS APDL explicit solver for different indentation depths and hole diameters in order to evaluate the compressive circumferential stresses, optimal process parameters and relevant geometric features. Fatigue tests are performed in order to determine the cycles to failure and the corresponding Wöhler diagram

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On the fatigue behavior of cold expanded fastener holes subjected to bolt tightening

Cited by 53 publications

References 38 publications

Experimental assessment of the redistribution of 3-D residual stresses during early fatigue at split-sleeve cold expanded reamed A/C fastener holes

Experimental assessment of the redistribution of 3-D residual stresses during early fatigue at split-sleeve cold expanded reamed A/C fastener holes

Effects of chamfering, cold expansion, bolt clamping, and their combinations on fatigue life of aluminum–lithium alloy single plate

Effect of the indentation process on fatigue life of drilled specimens

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