Analysis Of Dynamic Contact Characteristic And Time-varying Stiffness Of Gear Pair Under Different Failure Modes

Gear transmission is currently one of the most widely used transmission form,which plays a very key role in the transmission system of aviation,aerospace,ship,automobile,chemical industry,etc.With the development of gear transmission in the direction of high speed and high power,the higher requirements are needed on the operation performance of gear transmission.The gear failure such as gear wearing,pitting,scuffing and cracking are widely exist in all kinds of gear transmission,which affect the stability and reliability of equipment operation,cause production safety accidents and result in economy loss.Therefore,it necessary to conduct analysis of dynamic contact characteristic and time-varying meshing stiffness of gear pair under different failure modes,and it has important theory significance and great engineering value to ensure the stability and reliability of gear transmission.In order to reveal the relationship between gear failure and meshing stiffness of gear pair,this thesis focuses on gear failure such as gear wearing,pitting,scuffing and cracked tooth which exist in the gear transmission,analysis of dynamic contact characteristic and time-varying meshing stiffness of gear pair under different failure modes are conducted.The main work in this thesis can be summarized as follows:(1)The time-varying meshing stiffness of gear pair with the hertzian contact,bending,shear,axial compressive and matrix elastic stiffness be take into account is calculated by using analytical method.To verify the correctness of the analytical method,the contact finite element model of gear pair is built and the time-varying stiffness of gear pair is calculated by using finite element method.Based on explicit dynamic analysis method,dynamic contact analysis of gear pair is conducted.The dynamic model of gear transmission is built to study the dynamic contact characteristic of gear pair.(2)The mechanism of gear wearing is studied,the volume of uniform gear wearing is calculated by using the calculation formula of gear wearing.The uniform gear wearing is introduced into the calculation formula of the stiffness of gear.Based on energy method,the calculation formula of the time-varying meshing stiffness of gear pair with uniform gear wearing is derived.The correctness of the calculation formula is verified by using finite element method.Then analysis of the effect of different gear wearing situation to the time-varying meshing stiffness of gear pair is conducted.And to study the effect of gear wearing to the dynamic contact characteristic of gear pair,dynamic analysis of gear pair with gear wearing is conducted.(3)The mechanism of gear pitting is studied,the distribution of gear pitting on tooth surface is analyzed and the size and depth of gear pitting is estimated.The gear pitting which is simplified as a small round pit is introduced into the calculation formula of the calculation formula of the stiffness of gear.Based on energy method,the time-varying meshing stiffness of gear pair with gear pitting is calculated.The correctness of the energy method is verified by using finite element method.Then analysis of the effect of different gear pitting situation to the time-varying meshing stiffness of gear pair is conducted based on analytical method.To study the effect of gear pitting to the dynamic contact characteristic of gear pair,dynamic contact finite element analysis of gear pair with gear pitting is conducted and vibration differential equation of gear transmission is solved.(4)The mechanism of gear scuffing is studied,the distribution law of gear scuffing on tooth surface is analyzed and the size and depth of gear scuffing is estimated.The gear scuffing which is simplified as a rectangular groove is introduced into the calculation formula of the stiffness of gear.Based on energy method,the calculation formula of the time-varying meshing stiffness of gear pair with gear scuffing is derived.And the correctness of the calculation formula is verified by using finite element method.Then analysis of the effect of different gear scuffing situation to the time-varying meshing stiffness of gear pair is conducted.To study the effect of gear scuffing to the dynamic contact characteristic of gear pair,dynamic analysis of gear pair with gear scuffing is conducted.(5)The mechanism of gear cracking is studied,the distribution law of gear cracking on tooth surface is analyzed and the size and depth of gear cracking are estimated.The gear cracking which is simplified as a straight crack is introduced into the calculation formula of the stiffness of gear.Based on energy method,the time-varying meshing stiffness of gear pair with gear cracking is calculated.The correctness of the energy method is verified by using finite element method.Then analysis of the effect of different gear cracking situation to the time-varying meshing stiffness of gear pair is conducted based on analytical method.To study the effect of gear cracking to the dynamic contact characteristic of gear pair,dynamic analysis of gear pair with gear cracking is conducted.