This paper mainly analyzes the case of dynamic response model simulation 3. In this case, the stiffness excitation and friction excitation are introduced into the gear dynamic model at the same time. The Runge Kutta method is used to obtain the dynamic response of the gear system with different gear states under the influence of the stiffness and friction excitation at the same time The vibration response of driven gear along the meshing line is analyzed in time domain and frequency domain.
The vibration signal within 0.1s is given in Fig. According to Fig. 1, the amplitude of the vibration response signal of the pitting fault gear increases gradually with the increasing of the pitting fault degree. Under the condition of healthy gear, the time domain of vibration signal is relatively stable, and the amplitude of the signal is 0.00048 ‰. As indicated by the red arrow in Fig. 1, the vibration response signal of pitting-1 gear tooth is the vibration response signal. The signal amplitude in pitting-1 is not obvious, and the fault feature is relatively weak. The amplitude of pitting-1 is 0.00052 ‰. The amplitude of pitting-2 and pitting-3 speed signals are 0.00056 ／ and 0.00063 ／ respectively. Compared with the healthy gear, the signal amplitude of pitting-2 and pitting-3 increases obviously, and the fault characteristics are relatively obvious.
The RMS value and peak peak value of vibration speed signal in case III under different gear states are shown in Fig. 2 and Fig. 3 respectively. It can be seen that with the aggravation of gear pitting fault, RMS value and peak peak peak value almost increase linearly; when the gear pitting degree is the most serious, RMS value and peak peak peak value reach the maximum value; with the aggravation of gear pitting fault, RMS value and peak peak peak value increase linearly The growth trend of pitting-3 is the largest.
The frequency spectrum of the speed signal of the dynamic response of the gear is analyzed. The spectrum of the first six times of the meshing frequency of the vibration response is given in Fig. 4. The spectrum of the healthy gear only has the meshing frequency and its harmonic components. It can be observed that the amplitudes of one meshing frequency Fe and double meshing frequency 2Fe increase steadily with the aggravation of pitting fault degree compared with healthy gears. Through the analysis of higher meshing frequency, the higher harmonic of meshing frequency has the same characteristics. Fig. 5 shows a local enlarged view of the frequency component around the meshing frequency. With the occurrence of gear pitting fault, the side frequency around the meshing frequency will increase significantly, where the frequency difference between the side bands △ f = 4.9hz is approximately equal to the gear shaft rotation frequency f2 = 4.63hz. At the same time, the amplitudes of these sidebands will increase steadily with the increase of gear pitting.