scholarly journals Real-Time and Quantitative Measurement of Crack-Tip Stress Intensity Factors Using Digital Holographic Interferometry

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Haiting Xia ◽  
Rongxin Guo ◽  
Feng Yan ◽  
Heming Cheng
Keyword(s):  
Stress Intensity ◽  
Real Time ◽  
Phase Difference ◽  
Holographic Interferometry ◽  
Quantitative Measurement ◽  
Crack Tip ◽  
Mode I ◽  
Mode I Crack ◽  
Open Issue ◽  
Crack Tip Stress

Detection of the crack in an object is a critical problem for the health monitoring of a transparent object. The real-time and quantitative measurement of the crack-tip stress intensity factor (SIF) remains an open issue. In this paper, an approach for real-time and quantitative measurement for the SIFs of a Mode I crack is presented based on digital holographic interferometry (DHI). A transmission digital holographic system is established to measure the phase difference of an object wave during loading. The expression to achieve the SIF from the phase difference is formulated. To enhance the accuracy of measurement, calibrated phase unwrapping based on least-squares and iteration and median filtering is applied to retrieve the actual phase from the noisy wrapped one. The SIFs of the Mode I crack in a transparent polymethyl methacrylate (PMMA) specimen are measured by this approach. The results are compared with the theoretical ones to demonstrate the feasibility of the proposed approach.

Dynamic Analysis of a Mode I Propagating Crack Subjected to a Concentrated Load

2003 ◽  
Vol 70 (5) ◽  
pp. 668-675
Author(s):  
Y.-L. Chung ◽  
M.-R. Chen
Keyword(s):  
Stress Intensity ◽  
Wave Speed ◽  
Complete Solution ◽  
Crack Tip ◽  
Dynamic Effect ◽  
Mode I ◽  
S Wave ◽  
Dynamic Stress Intensity Factors ◽  
Concentrated Load ◽  
Self Similar

This work investigates the phenomenon of mode I central crack propagating with a constant speed subjected to a concentrated load on the crack surfaces. This problem is not a self-similar problem. However, the method of self-similar potential (SSP) in conjunction with superposition can be successfully applied if the time delay and the origin shift are considered. After the complete solution is obtained, attention is stressed on the dynamic stress intensity factors (DSIFs). Analytical results indicate that the DSIF equals the static stress intensity factor if the crack-tip speed is very slow and equal to zero if the crack-tip velocity approaches the Rayleigh-wave speed. However, the dynamic effect becomes obvious only if the crack-tip speed is 0.4 times faster than the S-wave speed. Moreover, the combination of SSP method and the superposition scheme can be applied to the expanding uniformly distributed load acting on a portion of the crack surfaces.

The dislocation-free zone at a mode I crack tip

1995 ◽  
Vol 50 (2) ◽  
pp. 165-173 ◽  
Author(s):  
Jianqiao Chen ◽  
Shigeo Takezono
Keyword(s):  
Crack Tip ◽  
Mode I ◽  
Mode I Crack ◽  
Free Zone

The Asymptotic Elastic-Viscoplastic Field at Mode I Dynamic Propagating Crack-Tip

2007 ◽  
Vol 348-349 ◽  
pp. 817-820
Author(s):  
Zhen Qing Wang ◽  
Ji Bin Wang ◽  
Wen Yan Liang ◽  
Juan Su
Keyword(s):  
Crack Tip ◽  
Viscosity Coefficient ◽  
Plastic Strain Rate ◽  
Mode I ◽  
Mode I Crack ◽  
Moving Crack ◽  
Dynamic Propagating ◽  
Propagating Crack ◽  
Hardening Condition ◽  
Elastic Unloading

The viscosity of material is considered at propagating crack-tip. Under the assumption that the artificial viscosity coefficient is in inverse proportion to the power law of the plastic strain rate, an elastic-viscoplastic asymptotic analysis is carried out for moving crack-tip fields in power-hardening materials under plane-strain condition. A continuous solution is obtained containing no discontinuities. The variations of the numerical solution are discussed for mode I crack according to each parameter. It is shown that stress and strain both possess exponential singularity. The elasticity, plasticity and viscosity of material at the crack-tip only can be matched reasonably under linear-hardening condition. The tip field contains no elastic unloading zone for mode I crack.

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