压力管道断裂参数的测算

EXPERIMENTAL DETERMINATION OF FRACTURE PARAMETERS FOR PRESSURIZED PIPING

针对裂纹尖端位移与应变场的特点，将贴片云纹干涉法引入含缺陷压力管道断裂参数的测算。基于波前干涉理论得到了压力管道表面位移与应变公式，探讨了断裂参数的测试原理，发现管道曲率的存在会使测试结果对刚体位移敏感起来，尤其当曲率很大时，即使采用对称入射光路，也不能忽略刚体位移的影响。为提高测试精度，改进了贴片云纹干涉法的测试技术和操作工艺，研制出胶片切口、定位和粘贴装置，编制了测试数据处理软件。实测了三根管道的断裂参数，结果表明，实测应力强度因子和裂尖张开位移与断裂理论中的Ｄ－Ｍ模型估算值相接近，塑性区内的Ｊ积分并不守恒，越靠近弹性区，Ｊ积分测试值越小并与理论计算值越相接近。

In view of the speciality of displacement and strain fields around crack tip,the test procedure of sticking film moire interferometry has been introduced into the measuring of fracture parameters for pressurized piping.With the theory of wavefront interference,equations representing the displacement and strain in piping surface has been obtained.Measuring theory of fracture parameters has also been examined.It is found that the measuring results obtained by sticking film moire interferometry become sensitive to rigid body movements due to the existence of piping curvature.Furthermore,when the curvature and the area to be measured are big enough,the effects of rigid body movements to the measuring results may not be eliminated even the symmetric incident light path is adopted.To increase the measuring accuracy,some improvements on experimental techniques of sticking film moire interferometry have been made,some supplementary devices relating to the cutting,fixing,and sticking of the film are devised.Moreover,a software of measured data processing is developed.With the improved sticking film moire interferometry,the displacement field,strain field,strees intensity factor,crack opening displacement and J-integral around the axial through crack tips of three pipings are measured.It is showed that the measured stress intensity factor and crack opening displacement are approximate to the theoretical solutions based on“D-M”model,value of J-integral in plastic region around crack tip varies as the integral path ,and as the integral path come near the elastic region,J-integral value decreases to the theoretical solution.