Prediction And Experiment Of Plastic Gear Contact Fatigue Life

Compared with metal gears,plastic gears are largely used in appliances,healthcare,communication industries etc.,due to low destiny,low cost,low density,corrosion resistance,and self-lubricating qualities.The dominant failure modes of plastic gears are excessive wear and fatigue fracture during the running period.As the sufficient lubrication in the power transmission field,contact fatigue failure is the familiar failure mode of plastic gears.However,plastic gears have the characteristic of viscoelastic response,large deformation,serious friction and wear in the contact area,which are significantly different from metal gears.In this work aiming at common ground for the durability performance of plastic gears,combined with the requirements of power transmission fields for high fatigue life,high service reliability and high operation efficiency of plastic gear,perdition and experiment method of plastic gear contact fatigue life are studied.In this work,the strong correlation between contact fatigue life and running temperature of plastic gears is analyzed.The plastic gear contact fatigue life numerical model is established based on the thermos-elasto-plastic constitutive relation and the multiaxial fatigue criterion.The influence of running temperature and loading level on the tooth flank durability performance is discussed,and correction computation of plastic gear contact fatigue life is proposed.Main contents are described as follows:1)Plastic gear contact fatigue life prediction model.Plasitc thermos-elasto-plastic constitutive relation is deduction,and the Brown-Miller-Morrow fatigue criterion is corrected by lubricant characteristic parameter.Contact fatigue numerical model of plastic gear is established considering the running temperature influence;2)Plastic gear contact fatigue experiment.The steel-plastic gear pair durability experiment is carried out by power open gear running test rig with measurable methods of while light interferometer,gear precision instrument,infrared thermal image system and so on.The test gear geometric parameter and test process for plastic gear contact fatigue experiment are determined,and the contact fatigue S-N curve is draw by less test point method;3)Plastic gear contact fatigue life correction computation.The relation between temperature and stress during the durability of plastic gears is proposed,and the equivalent stress S-N curve is charted according to the numerical model.The lubricant characteristic parameter is introduced to the contact fatigue life prediction equation.