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本文针对90°弯曲光纤连接块在随机振动环境下容易失效和产生界面裂纹扩展问题,采用ANSYS仿真分析其应力的分布情况和裂纹扩展规律。首先,研究影响该基板固有频率的因素,并确定在最小弯曲损耗时该基板的固有频率和模态,然后结合军用标准电子产品环境应力筛选方法,进行随机振动试验,将得到的应力分布作为边界条件计算J积分。研究得出,随机振动下满足最小弯曲损耗时的模型在振动频率为440.45~479.33Hz之间容易发生共振,当预置的裂纹长度大于0.094mm时,裂纹开始扩展,易发生低应力脆断,且裂纹尖角J积分值随着预置裂纹长度的增加呈现线性增长。
In this paper, the problem of 90 ° bend fiber connection block failure and interface crack propagation in random vibration environment is analyzed. The stress distribution and crack propagation are analyzed by ANSYS. Firstly, the factors that affect the natural frequency of the substrate are studied, and the natural frequency and modal of the substrate at the minimum bending loss are determined. Then, the random vibration test is carried out in combination with the environmental stress screening method of military standard electronic products. The obtained stress distribution is taken as the boundary Conditions to calculate J integral. The results show that the model with the minimum bending loss under random vibration is easy to resonate at the frequency of 440.45 ~ 479.33 Hz. When the preset crack length is more than 0.094 mm, the crack begins to expand and low stress brittle fracture easily occurs. The integral value of crack tip angle J increases linearly with the increase of pre-crack length.