某电子设备随机振动故障分析

目的 探究某批次电子设备随机振动环境筛选试验中故障发生原因.方法 首先对电子设备环境试验初步分析,确定设备螺钉点布置合理,结构本身无明显缺陷,但试验夹具可能导致振动载荷放大.通过Abaqus有限元软件仿真分析电子设备失效情况,同时开展试验确定振动夹具的固有频率,并绘制电子设备实际所受随机振动功率谱密度曲线,以该功率谱密度曲线为输入,开展有限元仿真,验证失效模式,并在此基础上完成故障复现试验,制定相应的改进措施.结果 有限元仿真得到电子设备3Sigma应力为22 MPa,在结构强度容许范围内.通过试验确定振动夹具固有频率与电子设备前两阶模态频率重频,发生共振,导致激励被放大,电子设备存在过考核,从而发生破坏.以设备实际所受功率谱密度曲线为输入条件,仿真得到3Sigma应力为52 MPa,超过焊接强度极限,导致焊点失效破坏.为进一步验证失效原因,使用原振动夹具完成故障复现试验,并改进试验夹具开展对比试验.结论 随机振动试验夹具的设计,应避免夹具固有频率与电子设备重频,从而导致设备破坏,合理选择设计夹具能有效避免电子设备遭受过考核.

Random Vibration Failure Analysis of an Electronic Equipment

In order to analyze the causes of failure in random vibration test of electronic equipment. Firstly, the environmental test of electronic equipment was analyzed, it was determined that the screws were arranged reasonably and the structure had no obvious defects, but the test fixture might lead to the amplification of vibration load. Use ABAQUS, a finite element software, to analyze the failure of electronic equipment, in the meanwhile, through tests to determine the frequency of the test fixture, and drew the actual PSD (power spectrum density) curve of the random vibration, a finite element simulation was finished which take the PSD curve as input. On this basis, the failure recurrence test was completed, and the corresponding improvement measures were formulated. The 3sigma stress of the electronic equipment was 22 MPa by finite element simulation, which was within the allowable range of structural strength. The frequency of the test fixture were repeated with the frequency of the electronic equipment, and the vibration load was amplified due to resonance, thus the electronic equipment was damaged. Taking the actual PSD curve as input, the simulation results showed that 3sigma stress is 52 MPa, which exceeded the welding strength, leading to the failure of the solder joint. In order to further verify that the failure reason was the amplification of the vibration load by the test fixture, the original test fixture was used to complete the failure recurrence test, and the fixture was improved to carry out the comparative test. The design of the test fixture should avoid the same frequency between the fixture and the electronic equipment, which will lead to the damage of the electronic equipment caused by resonance, a reasonable design of test fixture can effectively avoid the electronic equipment from excessive testing.