| With the rapid development of modern industry,gear is the most important basic component,it is widely used in the field of mechanical industry.In recent years,In recent years,China's mechanical manufacturing and processing level is constantly improving,it requires the development of gear transmission to the trend of high speed,heavy load and high reliability,and the accuracy of gear transmission is required to be higher and higher.Under the condition of high speed and heavy load,the friction of meshing gears is produced because of contact,accompanied by a lot of friction heat.The heating of the gear body will cause expansion and deformation,and the deformation of the heated gear teeth will rapidly reduce the meshing accuracy of the gear,and then the transmission error will be generated,which will cause the vibration and noise increase of mechanical equipment.At the same time,if the gear temperature is too high,the performance of the lubricating oil on the gear surface will become poor and the viscosity will be reduced,which will change the gear surface lubrication from elastohydrodynamic lubrication to oil shortage lubrication,and even dry friction causes the teeth to be glued.Through the reliability evaluation of the thermo elastic coupling process of the gear transmission system,it can provide an important theoretical basis for the dynamic optimization and life extension design of the gear transmission system,which has important research significance and practical value.In this paper,based on the theory of thermal elastic coupling,the theory of gear engagement and the theory of reliability design,a parameterized dynamic finite element model of spur gear engagement transmission is established by using APDL programming.The change rule of dynamic contact stress and thermal elastic coupling contact stress in the process of spur gear engagement transmission are solved and analyzed,and the influence of gear parameters on the engagement contact stress is analyzed.On this basis,according to the theory of thermal and elastic coupling,the calculation method of the fatigue life in the process of spur gear transmission is established,and then the reliability sensitivity of the gear parameters to the thermal and elastic coupling fatigue damage is analyzed.The main contents of the study are as follows:(1)The contact finite element simulation model of dynamic gear transmission is established,and the contact stress of gear is obtained and studied.The influence of four gear parameters,gear module,speed,gear width and resistance distance,on the contact stress of gear is analyzed.(2)The finite element simulation model of thermal and elastic coupling of gear transmission is established,the modeling steps of thermal and elastic coupling of gear transmission are discussed,and the stress and temperature fields of thermal and elastic coupling of gear transmission at different times are analyzed and calculated.(3)Based on the theory of fatigue damage,the change rule of fatigue damage in different positions of gear teeth is analyzed.(4)According to the response surface method,the limit state function of the tooth contact strength is obtained,and the probability sensitivity of each random variable of the gear to the limit state function is analyzed to obtain the sensitivity of various random factors to the reliability of the tooth contact strength under the dynamic contact state of the gear,and the reliability sensitivity analysis is carried out;the sensitivity calculation and analysis of gear fatigue life under the coupling of heat and elasticity are carried out.Through the sensitivity analysis of the dynamic model of the gear transmission system,the law of the influence of various gear parameters on its dynamic performance is mastered.Based on this,the dynamic optimization design of the gear transmission system is carried out to extend its service life.Therefore,this research has important theoretical research value and engineering reference significance. |
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