Vertical Deflection and Energy Dissipation Analysis of Jointed Structure Considering Microscopic Roughness

The bolted joint is a widely used assembly mechanism in engineering practice. In this work, based on the fractal theory, the slip behavior at the bolted joint interface is studied considering the effects of surface topography. The basic mathematic model is established to describe a press-fit joint under the coupling effects of applied force at the free end and nonuniform pressure along with the interface, in which the bolted joint is considered as two contact cantilever beams. According to the fractal method, the friction force of a single asperity is given, and the friction force of the whole interface is derived by the integration of friction force of all microscopic asperities. The friction coefficient is obtained by combining friction force and the applied force, in which the influences of surface morphology are embedded. Subsequently, the model of slip motion characteristics is established on the basis of the fractal friction coefficient. Results reveal that a smoother surface leads to a small friction coefficient and large deflections as well as relative slip directly, which is consistent with common knowledge. While the effects of surface morphology on energy dissipation and damping ratio of bolted joint exhibits unmonotonous that the minimum damping ratio does not always occur in the smoothest case.