远场应变法测量应力强度因子

本文给出一种将常规电阻应变片贴在距裂纹尖端较远处测量Ⅰ型裂纹应力强度因子K_1的方法。此法实际上是一种实验法与数值法相结合的方法。用实验法测出应变,应变又可以用含待定系数的Williams级数表示,它们组成一组线性代数方程组。解此方程组,可获得待定系数,由待定系数与应力强度因子的已知关系,可求出K_1。 远场应变测量法,避开了裂纹尖端邻域应变梯度很大的区域和可能的塑性区,因而应变测量比较准确。 测出的应变输入数据处理设备及计算机就可以快速实时地知道含裂纹结构在承载情况的K_1,便于进行破坏控制,使设备安全而可靠的工作。

Far Field Strain Methods for Determining the Stress Intensity Factor

By adhering the conventional strain gauges to a place sufficiently far from the crack tip, a method for determining the open-mode Stress-Intensity Factor (SIF) K1 is developed in this paper. In fact, it is a combination method of the experimental results with the numerical way. The strain can be determined from experiments and expressed as the Williams series containing unknow coefficients, forming a series of algebraic linear e-quations. Solving those equations and with the relationship of unknow coefficiends and the SIF, we can obtain K1. Because the strain gages are placed far from the plastic zone so as to avoid the high stress gradiant region at the vicinity of crack tips the determination is sufficient accurate. Inputting the strain values into the data processing equipment and computer, we can quickly obtain the K1 for a crack structure under loading condition. It is convenient to perform the destruction control to ensure the equipment running safely and reliably.