The existing problems of the original contact fractal model of friction pair faces of mechanical seals were analyzed

and the original model was modified.The relationship between bearing area ratio of asperity and face pressure on the friction pair faces was obtained.In the modified model

the effects of film pressure of fluid between the end faces of friction pair

the differences between real micro contact area and micro contact sectional area of asperity were taken into account.The relationship between elastic-plastic deforming asperity contact pressure and contact area was expressed by a cubic polynomial

which satisfied the continuous and smooth conditions of the transformation of asperity contact area and contact pressure at the critical point of transition of asperity distorting state.According to the modified model

the influence factors of asperity bearing area ratio of friction pair faces matched by cemented carbide YG8-carbon graphite M106K of partial balance mechanical seals were analyzed.The results showed that the asperity bearing area ratio increased approximately linearly with spring pressure

increased monotonously nonlinearly with fluid pressure

increased at first and then decreased with the increase of fractal dimension

and decreased with the increase of characteristic length scale.The real contact area accounts for only a small part of the nominal contact area under normal operating conditions.