Contact mechanics and noise in gears

Sammanfattning: In this thesis, recent findings in the area of computational contact mechanics are applied to gear technology. The focus of this application is gear noise. One of the main goals is to calculate the so called transmission error, which is a measure that relates structural properties of a gear to gear noise.Computational methodologies are developed in order to analyze different types of gear problems. The finite element method forms the basis for the developed models. In addition to the finite element models of the gear wheels, contact laws are used in order to simulate the contact between the gear flanks. These laws are Signorini's contact law and Coulomb's law of friction and by expressing them as B-differential equations the application of Pang's Newton method for B-differential equations is enabled.The transmission error is calculated with good accuracy under both quasi-static and dynamic conditions. By incorporating Archard's wear law into the models, predictions of how wear affects the transmission error are made. It is found that wear can have a significant impact on gear noise.It is shown that friction by no means can be neglected when calculating the transmission error. In the dynamic calculations of this thesis, friction always increases the dynamic transmission error. It is also concluded that the effect from friction becomes more significant if shaft and bearing stiffnesses are small.