某型飞机作动筒壳体裂纹故障分析

Crack Analysis of A Certain Type of Actuator Shell

针对某型飞机作动筒在使用过程中壳体出现裂纹现象,使用工业CT扫描、实物分解检查、金相组织分析等观察裂纹形貌,并利用断口失效分析、壳体有限元分析、现场检查取证等方法对裂纹产生原因进行分析。结果表明:退刀槽的R角小于图纸要求,但有限元仿真结果显示,退刀槽的开裂R角位置未发生塑性变形,活塞杆和壳体磨损痕迹也在正常工作范围内,壳体的组织、硬度、材质正常,壁厚也符合技术要求,因此推断该壳体裂纹应为加工刀痕、疲劳应力和退刀槽的R值较小等多因素导致的疲劳裂纹,为偶发性故障,为降低壳体发生裂纹的概率,可采取对壳体退刀槽部位抛光、振动光饰等措施。研究结果为预防及降低裂纹故障发生率提供一定方法。

Directed at cracks on a certain type of actuator shell,crack morphology was observed by means of industrial CT scan,physical decomposition inspection and metallographic structure analysis,and crack reasons were analyzed by means of fracture failure analysis,shell finite element analysis and on-site inspection and evidence collection.The results show that the R angle of tool withdrawal groove is smaller than the drawing requirements,but the finite element simulation results reveal that the R angle position has no plastic deformation;the wear marks of piston rod and shell are also within the normal working range;the structure,hardness and material of shell are normal,and the wall thickness also meets the technical requirements;therefore,it is inferred that the shell cracks are fatigue cracks caused by factors such as machining tool marks,fatigue stress and small R value of tool withdrawal groove,and happen occasionally.To reduce the probability of shell crack occurrence,measures can be taken such as polishing tool withdrawal groove and vibration polishing,etc.The study can help prevent crack fault and reduce the occurrence of crack fault.