Simulation And Analysis On Gear Fault Characteristics Based On ANSYS/LS-DYNA

Gear reducer is an important part of the mechanical system. It plays an irreplaceable role, which can provide the mechanical system with the required torque and the corresponding rotational speed. Its working condition directly determines the overall performance of the transmission system. Gear damage can lead to a large number of economic losses, and even endanger the lives of human beings. Therefore, scholars always pay much attention to the reliability and safety of the gear transmission system.Reducer gear failure occurred in the later work will change gear meshing state, thus resulting in a different degree of fluctuations in the gear meshing process. These fluctuations include the vibration and noise of the gearbox. Due to their appearance, the gear meshing accuracy is reduced. In the process of high-speed operation, the teeth are more prone to pitting, crack and broken. Because of the existence of the tooth failure, the gear meshing vibration and shock will appear more obvious periodicity and the transmission performance will be greatly affected. So it is a hot topic to study the dynamic characteristics of the fault gear.In this paper, the finite element model of the gear is established, in addition to the static analysis, the dynamic characteristics of the dynamic simulation is also carried out. Based on the static analysis of the ANSYS software, the meshing stiffness of the gear in health state and fault state was calculated. Based on the dynamic analysis of the LS-DYNA software, the dynamic characteristics of the gear and the fault gear were calculated. At the end of the experiment, the test results of the fault gear and the healthy gear are verified.The main contents of this paper including:1) The establishment of finite element model of gear. In addition to the introduction of building the corresponding gear model with the CAD 3D software, this paper focuses on the establishment of four pairs of meshing gear with the help of APDL language: complete, broken teeth, 1mm of gear tooth crack, 3mm of gear tooth crack. Finally we divide network element of gear model with the hexahedral element. Having a hexahedral grid cell the result is more accurate than the tetrahedron element mesh, and the calculation speed is improved by more than one times.2) The static analysis of the gear with ANSYS. The meshing stiffness of the engagement period is calculated here. Results show that the meshing stiffness of gear tooth fault model becomes much smaller.3) The dynamic characteristics of the gear with the above four kinds of different conditions are analyzed with LS-DYNA software. In order to reduce influence of propagation path of vibration signals as far as possible, the acceleration signal on the wheel and meshing force curve are extracted, and we can observe the effects of the tooth fault on these parameters. Because of the existence of the tooth fault, the meshing force near fault gear tooth has a mutation and vibration signal gets much larger. The displacement and acceleration signal of the tip of crack in fault gear have been changed correspondingly.4) In order to verify the rationality of the simulation results, the gear running test is carried out on the closed power flow test bench, and the vibration signals are collected and analyzed. Compared with the normal gear, three directions of the acceleration signal of fault gear are changed in different degrees. The experimental results are in agreement with the simulation results.