Multi-scale friction model considering interfacial topography and microstructure in ultra-low-temperature forming

Accurately describing the actual frictional behavior of tool-sheet interface during ultra-low-temperature forming is crucial for fabricating high-performance aluminum alloy thin-walled parts, but still faces significant challenges. Therefore, this paper developed novel multi-scale friction and contact models that considering real topography and microstructure of interface. The interface topography was determined by extracting the real profiles of tool and sheet surfaces, fitting and counting the geometry of surface asperities. The mechanical parameters of sheet soft surface microstructure were determined by relationship between grain size, stress and strain established trough constitutive modeling. The findings showed that newly proposed multi-scale friction model can not only accurately predict single asperity and macro-scale friction coefficients, but also quantitatively calculate adhesive and plowing friction coefficients.