DETERMINATION OF T-STRESS FOR THREE-POINT BENDING NOTCHED BEAMS
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摘要: T应力是存在于裂纹尖端平行于裂纹方向的应力，是裂纹尖端应力级数展开式中的常数项，它对裂缝尖端应力场的贡献不容忽视。三点弯曲梁是普通实验室中用来测定试件断裂性能的基本几何形式，为保证这些断裂参数确定的有效性，必须首先确定裂纹尖端T应力的大小，才能明确T应力对断裂参数的影响程度。该文通过有限元数值模拟得到跨高比为4的三点弯曲缺口梁和纯弯作用下单边裂纹尖端的T应力大小，与已有文献的比较验证了有限元计算的有效性。在此基础上根据圣维南原理，由跨高比为4和纯弯作用这两种情况下的T应力推导出一般跨高比情况下裂纹尖端的T应力表达式，并以跨高比为6、8和10三种情况为例，进行了计算并与该文的有限元计算结果进行比较，验证了该文提出的T应力计算公式的可靠性。Abstract: The T-stress which acts parallel to a crack, which corresponds to the constant term in the stress series at the crack tip, and its influence on the stress field can not be ignored. Three-point bending beam is generally used for testing fracture parameters in ordinary laboratories. Under this circumstance, T-stress at the crack tip must be determined first to see whether its value would influence the fracture parameters. In this paper, finite element program Abaqus is used to derive the T-stress for a three-point bending beam with a span-to-depth ratio of 4 and a single-edge notched beam subjected to pure bending. Thereafter, a general expression for T-stress of three-point bending beams of arbitrary span-to-depth ratio is presented based on St. Venant Principle. T-stress of three-point bending beams with span-to-depth ratio of 6, 8 and 10 is calculated using the proposed expression, and reasonable agreement is observed with the finite element analysis.
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Keywords:
- fracture mechanics /
- crack tip /
- three-point bending beam /
- T-stress /
- finite element analysis
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