【摘要】 为了克服目前常用的锤击测试方法在高频区域振动衰减过快、常规的激振及拾振器常采用接触方式使误差增大、以及对测试人员敲击技巧要求高等缺点,基于时域方法开发了轴流叶片激振和拾振均为非接触设备的模态测试系统。该系统采用Lab VIEW平台开发,除了具备测试轴流叶片的固有频率及振型功能外,基于频域带宽法和最小二乘法开发了模态阻尼及比例阻尼系数的辨识功能。该测试系统具有持续扫频激励的特点,可避免高频振动信号衰减过快而无法被准确测到的缺陷,同时它还具有无限次同工况重复及多点测试的优点,可避免测试中的漏频现象。研究结果表明:该测试系统能准确地测试出轴流叶片50~11000Hz内的模态特性,固有频率测试结果与锤击法的测试结果对比的相对误差均在0.6%以内,模态阻尼比测试结果自身对比的最大相对误差均在1%以下,比例阻尼系数求解误差都在可接受范围内。更多还原

【Abstract】 In order to overcome the rapid vibration attenuation in the high frequency region, the error growth due to using the contact way on vibration exciter and vibration exciter and the technical defects of testers, the axial flow blade vibration modes test system of no contact equipment based on the time domain method by Labview platform was developed. the natural frequencies and vibration modes were tested, the identifications of modal and proportional damping coefficients were developed, which were based on the frequency domain bandwidth method and the least square method. The high frequency vibration signal can be accurately measured and leakage phenomenon disappear through the continuous swept excitation of the system and repeated testing. The results show that the modal characteristics range from 50 Hz to 11000 Hz can be accurately measured. The relative error is within 0.6% by comparing the natural frequency test method and the hammer method, the maximum relative error is below 1% by the modal damping ratio method, and the solution error of the proportional damping coefficient is within acceptable range.更多还原