【摘要】 本文通过对裂纹转子参数共振及其分数倍频分量的理论分析及数值研究,指出:通过监视转子在2ω_c/3、2ω_c转速附近的分数倍频分量可用以诊断裂纹存在与否;而且监视这些分数倍频分量的变化在实际系统中是可能的。本文还通过对不同共振情况下,分数,整数倍频分量对裂纹的敏感性研究,指出了最易获取裂纹扩展信息的途径。更多还原

【Abstract】 At present, most researchers study sub-resonance of cracked rotors and make use of i/rcv (i is an integer) harmonics to diagnose if crack exists or not[1] [2] [3] [4]. But such monitoring appears to fail to determine definitely the existence of crack as it is only one among several likely faults. It is believed that the authors are the first to obtain the following three theoretical findings: 1. Through studying parametric resonance of cracked rotor, the authors find that if the vibration of the rotor in the neighborhood of speed 2ω_c/ 3 or 2ω_c(ω_cbeing critical speed of the rotor without crack) includes (1 / 2) / rev, (3 / 2) / rev,..., (9 / 2) / rev harmonics, crack exists on the rotor. The reason is that according to a previous paper [6] by the authors, parametric resonance occurs near 2ω_c/3 or 2ω_cwhen the rotor contains crack and such parametric resonance always includes (j/2) / rev (j= 1,3...9) harmonics. Other faults of the rotors don’t cause such resonance. 2. Through studying parametric resonance of cracked rotor the authors find that it is entirely feasible to monitor the change of (j/ 2) / rev harmonics. Although in an ideal rotor system (j/ 2)/ rev harmonics exist only at several definite speeds and make it difficult to monitor, the actual rotor system always contains some nonlinear factors and thus (j/ 2)/ rev harmonics exist in several ranges, in which parametric resonance occurs. 3. Through sensitivity study of both (j/ 2) / rev and i / rev harmonics to rotor crack under resonance (not just parametric resonance) condition, the authors believe that they are the first to find that it is best to monitor the change of q / rev harmonics near the resonance speeds (1/q)ω_c(q = 4,3,2,3/ 2,1,1 / 2). In the neighborhood of (l/q)ω_c, the q / rev harmonic is much bigger than any other harmonic except 1/rev harmonic and further more it is also most sensitive to crack depth.更多还原