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本文研究了在随机激振的情况下,由 FFT 分析仪所产生的谱进行传递函数(频率响应)计算的两种方法对偏度误差的敏感性。用 FFT 分析仪在模拟计算机模拟的单自由度系统上进行试验,其结果同理论预测有很好的一致性。文中指出,在谐振点附近,传递函数估计 H_2(S_(yy)/S_(xy)~*)的偏度误差大大小于通常采用的估计 H_1(S_(xy),/S_(x(?)))的偏度误差。对于一个给定的精度来说,若使用 H_2的计算方法,则所需的记录长度(从而还有试验时间)缩短约50％以上。分析还指出,如果在小模态质量的低阻尼结构上使用激振器激振,则尽量减小力传感器和激振器的运动部分质量是重要的。
In this paper, the sensitivity of the two methods to the transfer function (frequency response) calculation by the FFT analyzer to the skew error is studied under random excitation conditions. The FFT analyzer was used to simulate a single-degree-of-freedom system and the results were in good agreement with theoretical predictions. It is pointed out that the skew error of H 2 (S yy / S xy) ~ * in the transfer function estimation near the resonance point is much smaller than the commonly used estimators H 1 (S xy, / S x (?)) ) Skew error. For a given accuracy, using the H 2 calculation, the required record length (and therefore also the test time) is reduced by more than about 50%. The analysis also points out that it is important to minimize the mass of the moving parts of the force sensor and exciter if the exciter excitation is used on a low damping mass with a small modal mass.