腐蚀疲劳裂纹萌生的微机辅助监控与测试

MICROCOMPUTER-AIDED MONITORING AND MEASUREMENT OF CORROSION FATIGUE CRACK INITIATION

在作者以前工作的基础上,研制了疲劳裂纹萌生(FCI)微机辅助监控与测试系统。创新之处是:硬件采用了参考试样,可在意外事故发生后恢复试验;采用6522卡对电铃进行控制,提醒试验人员对FCI寿命进行记录;软件采用了低通滤波加数值补偿技术,既消除了数据的不平滑度,又避免了低通滤波带来的裂纹长度数据滞后于实际值的现象;采用了裂纹长度正偏置技术,消除了电位U型效应所造成的对裂纹长度的错误修正。系统在300M钢FCI试验中已得到成功应用。

A microcomputer-aided monitoring and measurement system for measuring fatigue crack initiation (FCI) life was developed in our laboratory based on the microcomputer-aided crack propagation measurement system established previously by the first author of the present paper.The new contributions are as follows:Firstey,a reference specimen was used in the hardware system in order to ensure continuation of fatigue test in case of unexpected accident,e.g.power cut off,instrument damage,fatigue machine alarm, computer misuse etc.Secondly,the 6522 interfacial card controls an electric bell to remind the operator to record data of FCI cycles.Thirdly,the low-pass filter and numerical compensation technique were used in the sofeware system,so as to diminish the non smooth degree of test data and to avoid the phenomenon of test value lagging behind practical value of crack length.Finally,crack length positive bais technique was adopted to eliminate erroneous correction caused by U-type effect of electrical potential values occuring in fatigue crack initiation test.The above-mentioned system has been successfully applied for monitoring cracking point of cycles and measuring initiation life of corrosion fatigue for 300M steel in air and in 3.5% NaCl solution.