加速度计悬丝断裂分析

Fracture Analysis of Suspension Wire in Accelerometer

惯性导航加速度计是惯导系统的关键元件之一,由于单轴摆式加速度计具有量程大、精度高而被广泛使用。对悬丝作为敏感线圈的支撑,在整个单轴摆式加速度计中属关键零件,同时也是加速度计中最易失效的零件。对悬丝断口、材质、工艺过程及测试环境进行了分析研究。结果表明:过载断裂是悬丝的主要失效形式,其次为疲劳断裂;悬丝失效受综合因素的影响,包括悬丝内部缺陷、材质不均、焊接过程控制问题、测试环境因素等,其中最主要的因素是悬丝内部各种缺陷。在此基础上,提出了严格控制悬丝加工工艺过程、改用可焊接性能良好的抗氧化无铅焊料KYHFSn96.5AgCu代替普通的铅锡焊料HLSn40PbA焊接等改进措施,有效地预防了加速度计悬丝的断裂失效。

The accelerometer is one of the key components in the inertial navigation system; single axis pendulum accelerometers are applied widely for the advantages of wide range and highly precise measurement. The suspension wire is used as the holding structure of the sensitive coil and thus is a critical part in the single axis pendulum acceleremeter. The failure mode and cause of the suspension wires were analyzed by facture surface observation, microstructure and technological process analysis, and service environment analysis. The results show overload fracture is the dominant fracture mode of suspension wires, and fatigue fracture is another fracture mode of suspension wires. The failure of the suspension wires resulted from several factors, including internal defects, microstructure ununiformity, improper welding procedure, and service environment, among which internal defects are the dominant factor of the failure. According to the analysis above, some improvement measures were proposed, such as strictly controlling technological process, and using KYHFSn96.5AgCu instead of HLSn40PbA as solder, and as a result, the fracture of suspension wires can be effectively prevented.