某动力涡轮盘裂纹扩展寿命研究

Study on Crack Growth Life of a Power Turbine Disk

为研究某动力涡轮盘GH4169合金的疲劳裂纹扩展特性,基于Paris公式建立裂纹扩展模型,完成3维裂纹扩展过程的有限元仿真分析,确定试验方案;采用电火花加工工艺在轮盘不同考核部位预制模拟裂纹,以缩短裂纹萌生时间;在高速旋转试验台上进行高温低循环疲劳裂纹扩展试验,试验过程中,在20500 r/min上限转速下进行9000次循环未发现裂纹,提速10%后进行3000次循环发现裂纹;又进行1700次循环,轮盘破裂。试验结束后,利用扫描电镜对疲劳断口进行观察,获得断口宏观、微观特征。将仿真结果与试验结果进行对比,表明仿真分析计算得到的裂纹扩展速率与试验结果有较好的符合性。

In order to study the fatigue crack growth characteristics of a power turbine disk GH4169 alloy,a crack growth model basedon Paris formula was established,and the finite element analysis of the 3D crack growth process was completed. The test scheme wasdetermined. In order to shorten the crack initiation time,simulation cracks were prefabricated at different parts of the wheel by EDMtechnology. High temperature and low cycle fatigue crack growth tests were carried out on a high speed rotating test rig. During the test,nocracks were found in 9000 cycles at the upper limit speed of 20500 r/min,and cracks were found in 3000 cycles after 10% increase inspeed. Disk ruptured after another 1700 cycles. After the test,the fatigue fracture was observed by SEM,and the macroscopic andmicroscopic characteristics of the fracture were obtained. By comparing the simulation results with the test results,it is shown that the crackgrowth rate obtained by the simulation analysis is in good agreement with the test results.