Abstract: Without considering the effect of lubricant, a computational method of mesh stiffness of a gear pair with tooth surface wear is developed for ideal cylindrical spur gear. The coordinates of tooth profile curves processed by a hobbing machine are obtained according to conjugate engagement theory. Based on the theory of Timoshenko beam, the mesh stiffness is calculated in consideration of bending, shearing and compressing, contacting and fillet-foundation deformation. Discrediting the tooth profile curve according to the equal-arc method is proposed aimed at wear of gear teeth in running process, and then effects of tooth wear on the cross-sectional area, area moment of inertia and real width of contact of a short discrete beam element are taken into account to calculate and analyze mesh stiffness with uniform wear, pitting and micro-pitting. The results show that the decrease of mesh stiffness caused by 100μm uniform wear is less than 2‰ and 15% micro-pitting results in a less than 10% variation of mesh stiffness. Mesh stiffness is not sensitive to early wear of gear teeth. This study is useful to improve the accuracy of dynamic modeling of a gear pair with tooth surface wear.

Key words: gear, health monitoring, mesh stiffness, wear