Equivalent modeling method of virtual material for flange connection structure based on contact mechanics experiment

It is essential to consider microscopic contact deformation on the joint surface when the dynamic properties of flange connection structure were characterized. In the study, an equivalent modeling method of virtual material based on microscopic contact experiment was proposed. First, the macroscopic model of flange connection structure was established and assembly process was simulated. Several subregions were divided according to the pressure distribution of joint surface. In each subregion, the pressure distribution was approximately uniform. Second, the microtopography of joint surface was measured experimentally, and the fractal parameters were calculated by power spectral density function method. At the same time, the contact mechanics experiment by industrial CT equipment was conducted to accurately measure the actual contact state of joint surface, and the mathematical model of contact pressures and ratios of actual contact area to nominal contact area was established. Next, the contact stiffness of joint surface was calculated based on fractal contact theory and the actual contact area measured by industrial CT equipment. Finally, the parameters of equivalent virtual material were calculated by weighted average of each subregion. In addition, a modal experiment of flange connection structure was conducted to compare with the simulation result. The result shows that the average relative error of natural frequency was 4.69% between experiment and simulation. It verified the accuracy and reliability of the equivalent modeling method of virtual material based on contact mechanics experiment.