无人机活塞顶穿孔机理的分析

Analysis on Piercing Mechanism of Piston Top of UAV

通过一系列方法对故障活塞及同批次活塞进行了分析和检测,结果说明活塞设计满足要求且最大应力未出现在活塞顶部。理化成分研究结果表明:活塞基体元素成分、金相组织均符合相关要求,无批次问题,但故障活塞的铸造缺陷相对较多;当出现异常时,在铸造缺陷处,合金相和初晶硅界面首先遭到高温熔蚀形成剥落、麻点及凹坑,当熔蚀进一步加剧时,形成线状及密集缺陷。因此得出结论:活塞无设计缺陷,未按时清理积碳造成的异常燃烧使故障活塞铸造缺陷处熔融进而失效,是造成本次故障的主要因素。

The fault piston and the same batch piston are analyzed and detected by a series of methods.The simulation results show that the piston design meets the requirements and the maximum stress does not appear at the top of the piston.The results of physical and chemical composition study show that the matrix elements and metallographic structure of piston meet the relevant requirements and there are no batch problems,but there are relatively many casting defects of faulty piston.When abnormal occurs,the interface between alloy phase and primary silicon is first peeled off by high temperature melting corrosion,hemp point and pit are formed,and when the corrosion is further intensified,linear and dense defects are formed.The final conclusion is as follows:the piston has no design defects and fails to clean up the differences caused by carbon accumulation on time.Constant combustion makes the casting defects of the faulty piston melt and then fail,which is the main factor causing the fault.