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盲孔法作为评定桥梁结构残余应力的重要手段被广泛应用,应变释放系数的确定是其测量精度的支配因素。本文基于敏感性分析并考虑钻孔后的加工硬化效应从有限元模拟的角度研究盲孔法应变释放系数随孔深、测量直径及板件厚度等因素的变化规律,并以标定试验加以验证,试验值与有限元解吻合良好。结果表明,应变释放系数A、B随孔深增加呈快降缓升的变化规律;当D/d<5时,应变释放系数随测量直径与孔径比值的上升变化显著,增长幅率有趋近于零的态势。应变释放系数A、B仅在厚度为12~14mm区间有小幅度的增加,其他厚度区间无明显变化。
Blind hole method is widely used as an important means to evaluate the residual stress of bridge structure. The determination of strain release coefficient is the dominant factor of measurement accuracy. Based on the sensitivity analysis and considering the work-hardening effect after drilling, the variation law of the strain-release coefficient of the blind hole with the hole depth, the measured diameter and the thickness of the plate was studied from the angle of finite element simulation and verified by the calibration test. Experimental results agree well with the finite element method. The results show that the strain release coefficients A and B change rapidly with the increase of the hole depth. When D / d <5, the strain release coefficient changes significantly with the increase of the measured diameter and the aperture ratio, and the growth rate approaches At zero situation. Strain release coefficient A, B only increased slightly in the range of 12 ~ 14mm thickness, but no significant change in other thickness range.