Experimental investigation of creep-crack-tip deformation using moiré interferometry

Kang, Bruce S.; Zhuang, Yufei; Liu, Q. K.

doi:10.1007/bf02325583

Cited by 5 publications

(3 citation statements)

References 12 publications

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“…This comes from the crack-tip blunting caused by the large creep deformation in the vicinity of the crack tips. This kind of crack-tip deformation, blunting and damage has been observed in a lot of experimental work of creep crack-tip deformation (Kang et al, 1992;Liu et al, 1998) and creep crack growth (Dean and Gladwin, 2007;Zhu et al, 1990;Tabuchi et al, 2004), typically as shown in Fig. 7 (Tab uchi et al, 2004) which shows that the crack tip has been blunted to a width of about 0.1 mm and a creep void damage zone with a size of about 0.8 mm appears in front of the blunted crack tip.…”

Section: Characterization Of the Constraint Parameter Under Creep Conmentioning

confidence: 91%

Effect of constraint induced by crack depth on creep crack-tip stress field in CT specimens

Wang

Liu

Xuan

et al. 2010

International Journal of Solids and Structures

106

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a b s t r a c tIn this paper, the effect of constraint induced by the crack depth on creep crack-tip stress field in compact tension (CT) specimens is examined by finite element analysis, and the effect of creep deformation and damage on the Hutchinson-Rice-Rosengren (HRR) singularity stress field are discussed. The results show the constraint induced by crack depth causes the difference in crack-tip opening stress distributions between the specimens with different crack depth at the same C*. The maximum opening stress appears at a distance from crack tips, and the stress singularity near the crack tips does not exist due to the cracktip blunting caused by the large creep deformation in the vicinity of the crack tips. The actual stress calculated by the finite element method (FEM) in front of crack tip is significantly lower than that predicted by the HRR field. Based on the reference stress field in the deep crack CT specimen with high constraint, a new constraint parameter R is defined and the constraint effect in the shallow crack specimen is examined at different distances ahead of the crack tip from transient to steady-state creep conditions. During the early stages of creep constraint increases with time, and then approaches a steady state value as time increases. With increasing the distance from crack tips and applied load, the negative R increases and the constraint decreases.

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Section: Characterization Of the Constraint Parameter Under Creep Conmentioning

confidence: 91%

Effect of constraint induced by crack depth on creep crack-tip stress field in CT specimens

Wang

Liu

Xuan

et al. 2010

International Journal of Solids and Structures

106

View full text Add to dashboard Cite

show abstract

“…Numerous optical examinations of crack‐tip deformations have been performed to estimate the stress state of a crack tip. These techniques include photoelastic methods [10], moiré interferometry [11–15], electronic speckle pattern interferometry [16], holographic interferometry [17], shearing interferometry [18], computer vision [19], caustics and numerical analyses [20], and full‐field optical methods [21, 22]. Despite the importance of optical stress‐analysis methods in fracture mechanics, there is a lack of suitable experimental techniques providing full‐field deformation measurement [23].…”

Section: Need For New Surface Characterisation Tools To Quantify Cracmentioning

confidence: 99%

Towards Prediction of Failure in Ti‐6AI‐4V Aerospace Materials by Surface Observations

Matikas

2011

Strain

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This paper deals with the development of a methodology for the prediction of material failure in metallic aerospace alloys by evaluating changes in surface characteristics directly prior to unstable fatigue crack propagation. The study is based on in situ nondestructive characterisation of the depression zone ahead of the crack tip of fatigue‐pre‐cracked titanium alloy specimens subjected to static loading. A relationship between the surface characteristics of the deformation zone ahead of the crack and the stress intensity factor of the material was obtained. This relationship was common to a variety of microstructural conditions such as mill‐annealed and β‐annealed microstructures. Based on the analysis, prediction of the impending fracture in cracked samples of the material was enabled. The outcome of this study can be used for optimising the service life of structural components.

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“…Now, some optical testing methods have been used in the investigation of dynamic performance of materials. Moiré interferometry method is a representative one, and it has been used in in-plane deformation measurements at elevated temperatures [1][2][3][4] .However, most of uses of moiré interferometry methofs are related to statistic and quasistaitc measurements because the testing precision will be severely affected by the rough environment when it's applied under high-speed impact loading.…”

Section: Introductionmentioning

confidence: 99%

Real-Time Measurements on Crack-Tip Deformation Fields of LY12 Samples under Impact Tension

Chen

Lan

Chen

et al. 2008

KEM

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In this paper, the deformation fields of LY12 crack samples loaded by an SHTB are real-time investigated with the time interval of 10 µs by an optical system, which consists of a high-speed camera, a flash light, a frame grabber and a synchronization device with the delay-time less than microsecond. The cracks are preset by using the three-points bending method in a MTS fatigue machine. The crack is 2mm long with a flare angle of 60 degree. During the experiments, the dynamic deformation images are captured by the high speed camera and analyzed by newly developed software based on Digital Correlation theory. And the displacements fields near crack-tips according to the changes of the flare angle and radius during the impact process are obtained. Experimental results acquired in this paper are proofed, by compared with the theoretical calculations.

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Experimental investigation of creep-crack-tip deformation using moiré interferometry

Cited by 5 publications

References 12 publications

Effect of constraint induced by crack depth on creep crack-tip stress field in CT specimens

Effect of constraint induced by crack depth on creep crack-tip stress field in CT specimens

Towards Prediction of Failure in Ti‐6AI‐4V Aerospace Materials by Surface Observations

Real-Time Measurements on Crack-Tip Deformation Fields of LY12 Samples under Impact Tension

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