Stress-Intensity Factors for Three-Point Bend Specimens by Boundary Collocation
Stress-Intensity Factors for Three-Point Bend Specimens by Boundary Collocation
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发表时间：
1965-12
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通讯作者：
B. Gross;J. Srawley
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作者：
B. Gross;J. Srawley
文摘：将边值配置法应用于Williams应力函数，确定了矩形截面三点弯曲试件单边应力强度因子K值。计算结果用无量纲量Y2=K2B2W3/M2表示，其中B和W为试件厚度和深度，M为跨中弯矩。对于三点弯曲，Y2作为相对裂纹深度a/W的函数略低于相应的纯弯曲的值(以前用同样的方法测定)，并且随着支撑跨度与试件深度的比S/W的减小而减小。当A/W值最大为0时，给出了Y2与A/W的曲线图。5和S/W分别等于4和8。结果对跨中荷载接触区扩展的变化相对不敏感，认为这与材料的屈服强度有关。结果与已发表的实验顺应性测量结果非常吻合；一组给出的Y2值高于目前的方法，另一组给出的值较低。三点弯曲试件的平面应变断裂韧度测量能力略低于四点弯曲试件，但这种差异的实际意义可以忽略不计。
Abstract : A boundary value collocation procedure was applied to the Williams stress function to determine values of the stress intensity factor K for single edge in rectangular section specimens subjected to three point bending. The results are presented in terms of the dimensionless quantity Y2 = K2B2W3/M2 where B and W are the specimen thickness and depth and M is the bending moment at midspan. The values of Y2 as a function of relative crack depth a/W for three-point bending are appreciably lower than the corresponding values for pure bending (determined previously by the same method) and decrease as the ratio of support span to specimen depth S/W decreases. Plots of Y2 against a/W are given for values of a/W up to 0. 5 and S/W equal to 4 and 8. The results were relatively insensitive to variations in the spread of the midspan load contact region, which was assumed to be related to the yield strength of the material. The results agreed fairly well with published results derived from experimental compliance measurements; one set gave higher values of Y2 than the present method, and the other set gave lower values. The plane-strain fracture toughness measurement capacity of three-point bend specimens is somewhat lower than that of four- point bend specimens, but the difference is of negligible practical importance.