Residual Stress Test of Expansion Casing
膨胀管残余应力测试

Residual stress in expansion casing is one of important factors affecting its squeezing and pressure resistance. In order to determine residual stress in an expansion casing, the testing method is essential. Among common testing methods, the hole-drilling method has superiority in mechanical measurements. Residual stress in expansion casings with J55 and K55 two specifications were tested respectively by hole-drilling method. According to the actual tested stress level and trial errors, the trial results were revised using relieved strain coefficients grading method to improve the test precision. Test results show that an expanded expansion casing exits circumferential and axis residual stress, and its outer surface has always compression residual stress. Comparing trial results with that from simulation, the errors met the engineering requirements, which indicates that the hole-drilling method is convenient, fast, accurate and effective.