In order to be able to carry out an optimal gear design with the aim of cost reduction and the careful handling of resources, load capacity is an important criterion for the evaluation of a gear. For the calculation of the flank and root load capacity, a precise loaded tooth contact analysis (LTCA) is necessary. With LTCA software like BECAL, influence numbers are used to calculate the deformation of the gear. These influence numbers are calculated with a BEM-module and considered for calculating the local root stress. This method simplifies the coupling stiffness in tooth width direction with a decay function and neglects the influence of local differences in tooth stiffness. In this publication, this simplification shall be questioned and evaluated.Therefore, a new method for calculating stress with FEM influence vectors is presented. This method enables the calculation of full stress tensors at any desired location in the gear with the efficiency of the influence number method. Additionally, the influence of local stiffness variations in the gear is taken into account. Various gear examples show the influence of material connections at the pinion root and the influence of the rim thickness of a wheel on the root stress. To validate the accuracy and the time efficiency of the new calculation method and to compare the results to current state-of-the-art simulations, a well-documented series of tests from the literature is recalculated and evaluated.
Innovative cold rolling technologies are important future production methods to gain more resource efficiency producing gears. Through current research at the Fraunhofer Institute for Machine Tools and Forming Technology (IWU), it is possible to produce running gears for use in vehicle transmissions by this method. The paper contends theoretical and experimental investigations on cold rolled gears to determine their properties in detail. The theoretical principles of material anisotropy following cold forming processes as well as the results of investigations on gear teeth are discussed. Different calculation methodologies to compute the efficient elastic behavior of an anisotropic material area are compared by applying them to measurement data of an Electron Backscatter Diffraction (EBSD). Furthermore, methods to simulate the rolling process are described and applied to the investigated gear. It is shown that the production method can have an effect on the elastic material behavior of gear teeth
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