Abstract: Normal contact stiffness is an important parameter affecting the dynamics performance of contact bodies. There are two main ways of calculating the normal contact stiffness: one is the traditional Hertz contact theory, and the other is modern microeconomic theory through setting up the fractal model. To accurately calculate normal contact stiffness between two cylinders’ joint interfaces, the fractal model of normal contact stiffness between two cylinders’ joint interfaces is established based on the reasonable expansion of the existing fractal model and the early stage of research results. This model can correctly reflect the conclusion influenced by the parameters of fractal dimension, roughness amplitude, material properties parameters, and the cylinder radius. Simulation results show that: as the parameters of fractal dimension, material properties parameters and the radius of the cylinders increase and the parameters of roughness decreases, the normal contact stiffness adds. What’s more, the stiffness of inner contact is larger than that of outer contact. The establishment of the model lays the foundation for the following calculation of the normal contact stiffness of gears or cylindrical bearings and gives a new theory supplement to the contact dynamics research.

Key words: Contact, Cylinder, Fractal theory, model, Normal contact stiffness