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Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering)  2010, Vol. 11 Issue (10): 782-788    DOI: 10.1631/jzus.A1000153
    
Estimation of the J-resistance curve for Cr2Ni2MoV steel using the modified load separation parameter Spb method
Chen Bao, Li-xun Cai
School of Mechanics and Engineering, Southwest Jiaotong University, Chengdu 610031, China
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Abstract  Based on load separation theory, the load separation parameter Spb method is an effective approach for estimating the J-resistance curve from records of load versus displacement directly, using one sharp cracked specimen and an additional reference blunt cracked specimen. However, the effect of the reference blunt cracked specimen on J-resistance determination was not explicitly considered in past work. In this paper, a modified load separation parameter Spb method was developed to eliminate this effect, and then a unique estimation of instantaneous crack length for one sharp cracked specimen could be obtained. Furthermore, a forced blunting calibration method was also adopted to determine the instantaneous crack length in the load inseparable region, referring to a normalization method. Experiments on steam turbine rotator steel Cr2Ni2MoV were carried out to estimate J-resistance curves using an unloading compliance method. By removing unload and reload data from load-displacement records, the J-resistance curve for the same sharp cracked specimen was estimated using the modified separation parameter Spb method. The results indicate that the modified Spb method completely eliminates the effect of the reference blunt cracked specimen on the instantaneous crack length determination of the sharp cracked specimen. However, different J-resistance curves in a small range of crack extension are present when different blunting coefficients are used in the blunting line equation. The J-resistance curve obtained from the modified Spb method agrees well with that obtained from the compliance method.

Key wordsLoad separation      J-resistance curve      Separation parameter Spb      Blunt cracked specimen      Forced blunting calibration     
Received: 08 April 2010      Published: 05 October 2010
CLC:  O346.1+2  
Cite this article:

Chen Bao, Li-xun Cai. Estimation of the J-resistance curve for Cr2Ni2MoV steel using the modified load separation parameter Spb method. Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2010, 11(10): 782-788.

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http://www.zjujournals.com/xueshu/zjus-a/10.1631/jzus.A1000153     OR     http://www.zjujournals.com/xueshu/zjus-a/Y2010/V11/I10/782

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