Lewicki explored the law of fracture and crack generation of two-dimensional gear teeth, and proposed a super safety design concept. The innovation of this concept is to put forward an idea to avoid the generation of cracks in the root of gear teeth as much as possible. After the root crack initiation, it is necessary to control the propagation direction of the crack so that the crack does not propagate towards the root of the tooth, so that the fracture failure of the tooth root will not occur. At the same time, the fracture characteristics of gear teeth are studied through the finite element simulation analysis, and the propagation path of the crack initiated at the root of the gear is simulated. The correctness of the conclusion is verified by comparing the simulation results with the experiment. The crack growth life of the gear with different flange thickness is studied, and the influence relationship between them is obtained The relationship between the crack propagation path and the different loading positions is obtained. Finally, a moving load model which can describe the actual situation more accurately is proposed. The accuracy of the model is that the load on the gear teeth changes during the meshing process. Based on the moving load model, the effect of Crack Closure Technology on crack propagation is analyzed and studied, and the results are compared with some experimental results The model has a good agreement.
Ural and Heber et al. Deeply analyzed and studied the law of crack propagation path ofby finite element method, and simulated the fatigue crack growth path of bevel gear based on the theory of elasticity and the software of FRANC3D independently developed by the research group of the author. Based on the weighted function method of crack opening displacement, the stress intensity factor of root crack propagation is derived, which provides a new calculation model for predicting crack propagation path. The two models can be used to predict the complete life of gears made of high strength alloy steel 42CrMo4.
Zouari and maater et al. Studied the crack propagation of root crack under bending stress by combining elastic mechanics with finite element method. The propagation path of gear crack under two-dimensional condition is obtained by elastic mechanics analysis, and the variation law of crack propagation path under different meshing stiffness conditions is studied. An improved total potential energy model is proposed, which can be used to predict the change of gear meshing stiffness under different crack propagation paths. This method provides a new idea for gear fault diagnosis. Finally, the location of crack initiation and its influence on the crack propagation are studied by experiment and simulation. By changing the loading position of the tooth surface, it is found that the crack initiation position is obviously different, and the crack propagation will develop to fracture along different paths.
Prakash and Kumar et al. Studied the influence of gear parameters such as modulus, tooth thickness and modification coefficient on the stress intensity factor of three-dimensional crack of gear, and analyzed the influence of the above gear parameters on the crack growth path and crack growth life in the process of crack growth and transient fracture.