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针对某航天器结构的随机振动疲劳损伤问题进行了研究。采用ANSYS软件建立了某航天器结构的有限元模型,并模拟振动台试验条件对其进行了多点激励随机振动响应分析;然后,根据振动响应结果得到结构敏感频率;并在现有样本法的基础上进一步考虑了振动敏感频率和平均应力对疲劳损伤的影响。具体通过在敏感频率附近密集采样而在远离敏感频率范围内稀疏采样的方式得到时域载荷谱;进而采用雨流法得到有效载荷谱,并结合Miner线性累积损伤理论和Soderberg方程估算了结构的疲劳损伤。最后将该方法计算的结果与Steinberg三区间法和现有样本法所得结果进行了对比,结果表明采用本文改进的样本法在少量取样情况下的损伤计算结果就能与三区间法基本一致,从而验证了该方法的适用性。相比较现有样本法,该方法既大大减少了工作量又提高了计算精度。
Aiming at the random vibration fatigue damage of a spacecraft structure, The finite element model of a spacecraft structure was established by ANSYS software and the shaking table test conditions were used to analyze the random vibration response of the spacecraft. Then, the structure sensitive frequency was obtained according to the vibration response results. Based on the further consideration of the vibration frequency and the average stress on fatigue damage. The time-domain load spectrum is obtained by intensive sampling in the vicinity of the sensitive frequency and sparsely sampling away from the sensitive frequency range. The rain load method is used to obtain the payload spectrum, and the structural fatigue is estimated by combining the Miner’s linear cumulative damage theory and the Soderberg equation damage. Finally, the results calculated by this method are compared with the results obtained by the Steinberg three-zone method and the existing sample method. The results show that the damage calculation results of the sample method using the improved method in this paper can be basically the same with the three-interval method Verify the applicability of this method. Compared with the existing sample method, this method not only greatly reduces the workload but also improves the calculation precision.