Stress Analysis of Gear Drives Based on Boundary Element Method Daniele Vecchiato@ University of Illinois at Chicago The stress analysis is performed as a part of TCA (Tooth Contact Analysis) for a gear drive. Unlike the existing approaches@ the proposed one does not require application of commercial codes (like ANSYS or ABAQUS) for derivation of contact model and determination of contact and bending stresses. The contacting model is derived directly by using the equations of tooth surfaces determined analytically. The boundary element approach allows to reduce substantially the number of nodes of the model. Determination of stresses caused by applied load is obtained directly for the applied contacting model for any position of meshing. The developed approach is illustrated by stress analysis of helical gears with modified geometry.