Numerical calculation and experimental validation of multi-scale three-dimensional leakage channels

Many non-contact clearances always exist within the contact interface when two rough surfaces are compressed. These continuous clearances form three-dimensional leakage channels, which are closely related to static seals. Considering the self-affinity and multi-scale characteristics of rough surfaces, this paper proposes a numerical solution framework for multi-scale three-dimensional leakage channels for the first time. First, an elastoplastic multi-scale contact algorithm is proposed by introducing magnification-based multi-scale contact criteria into semi-analytical contact computation. The rough surface scale is dynamically adjusted according to the degree of contact. Second, a reverse method is further proposed to reconstruct the real distribution of contact clearances on the basis of the principle of equivalent deformation superimposition. Subsequently, a dual-layer search algorithm for three-dimensional leakage channels is developed, which comprehensively accounts for the boundaries of rough surfaces and enables accurate identification of leakage pathways. X-ray computed tomography (CT) is then employed to measure non-contact clearances at metal contact interface for validation. The results indicate that the pore overlap ratio between the numerical simulations and experimental measurements is about 80 %. Given the potential sources of error inherent in the experimental procedure, these results are deemed sufficient to confirm the accuracy and reliability of the proposed method. Overall, the proposed numerical method for modeling multi-scale three-dimensional leakage channels holds significant value for engineering applications such as sealing, lubrication, and microfluidics.