三维光弹性测定应力强度因子K_Ⅰ的综合法

A SYNTHETIC METHOD OF THREE DIMENSIONAL PHOTOELASTICITY FOR DETERMINING STRESS INTENSITY FACTOR K_I

对利用三维光弹性试验数据计算应力强度因子K_I,提出一种新的算法——综合法。此法既解决了所需测量区域内条纹信息少的弱点,又克服了因裂纹尖端“钝化”而无法测到裂尖精确条纹值的困难。试验与计算结果表明此法误差小、精度最高。可应用测定受复杂载荷并具有复杂边界条件结构的应力强度因子。

A synthetic method to calculate stress intensity factor KI by use of the data obtained in the experiment of three dimensional photoelasticity is developed in this paper. The process of this method may consist of essentially three phases. 1.curve fitting the data measured around a crack to the area required;2.analysing the results experiment and determining the 'blunt' situation at the tip of crack;3.using Taylor series and extrapolating to obtain the stress intensity factor KI at the tip of crack. The method over-comes not only the measured deficiency of fringe information in the area but also the difficulty of measuring the accurate value of fringe at the tip of crack because of the 'blunt' situation. A comparison of the results obtained by three methods of calculating the data of a typical experiment about a semicircle surface crack of a specimen shows that the synthetic method is the most accurate.