Heavy duty gear is the core component of large equipment transmission. It is widely used in mining, metallurgy, building materials, petroleum, chemical industry, power station, forging, hoisting and transportation machinery and many other industries. If the gear has high performance, it will play an important role in prolonging the overall service life of Mechanical equipment. In the actual working environment, the service conditions of heavy-duty gears are bad and complex. They should not only bear the alternating load with high stress level, but also bear large shear stress and instantaneous impact stress. The tooth root bending stress has become an important factor leading to the failure of transmission gears of heavy equipment. In the process manufacturing industry, the transmission gear of heavy equipment often plays a very important role. Its normal operation directly affects the production efficiency of the whole production line. For example, once metallurgical and mining equipment such as deep-sea drilling equipment and converter dumping mechanism are shut down due to gear damage, in addition to the losses caused by the damaged equipment, it will disrupt the production rhythm of the whole production line, and the resulting economic losses will be immeasurable.
Due to the derivation and development of gear fatigue cracks, the mechanical system can not operate normally. Therefore, the prediction of gear fatigue cracks plays an important role in gear fatigue and life prediction in many industries such as mining, metallurgy, building materials, petroleum, chemical industry, power station, forging, hoisting and transportation machinery. The reason is that the transmission equipment of heavy equipment has complex structure and poor operating conditions, and the operation difficulty is far greater than that of ordinary equipment. However, the fundamental reason is that there is less analysis on the fatigue crack evolution behavior of heavy-duty transmission gears, that is, it is unable to clarify a series of problems such as how the crack is generated and why it is generated and expanded. Throughout the literature at home and abroad, there are few systematic explanations on the fatigue cracks of heavy-duty transmission gears.
At present, the research of fatigue crack evolution behavior lags far behind the research of feature extraction algorithm. In the age of underdeveloped computer, the core of “fatigue crack research” is to choose a simple mathematical model to describe the essence of failure. Today, with the increasingly developed technology, the research focus should focus on the dynamic response of equipment under complex working conditions, especially under extreme working conditions such as variable speed and variable load impact and random disturbance. Obviously, there is a lack of achievements in this field. The research object of this subject is the gear under the fatigue condition of heavy equipment transmission gear. The fatigue crack initiation and small crack propagation behavior are studied by the combination of test and numerical simulation, This research has important theoretical and practical significance for establishing a set of reliable fatigue life prediction method and improving the service life of heavy-duty gears.
Taking 42CrMo gear as the research object, the fatigue crack evolution behavior of 42CrMo gear is expounded from the perspective of fracture mechanics and plastic elasticity through the combination of test method and numerical simulation method. The fatigue crack growth rate of compact tensile specimens under mode I constant amplitude loading was analyzed. The fatigue fracture of gear teeth was analyzed by scanning electron microscope, and the macro and micro morphology were analyzed. Through the bending fatigue test of the self-designed and manufactured heavy equipment transmission gear, and then the test data analysis and numerical simulation are mutually verified by mathematical statistics, finally the large modulus gear similar to the heavy equipment transmission gear is designed and the corresponding numerical simulation is carried out, and finally the numerical simulation of fatigue crack propagation of a pair of meshing gears is verified. It provides practical reference significance for the design of heavy-duty transmission gear.