EFFECT OF BULK DEFORMATION ON VISCOPLASTIC ADHERING PROCESS - A NUMERICAL STUDY OF SOLID-STATE PRESSURE WELDING

Viscoplastic intimate contact process of uneven surfaces is numericall y studied by using the finite element model proposed in our previous p aper. The model treats only the case that the interfacial contact is t he rate determining step of the solid state bonding process. The distr ibution of the equivalent strain rate around the void surface is stron gly influenced by the bulk constraint conditions, i.e., the interfacia l deformation is greatly affected by the bulk deformation. The strain rate at the void tip is strikingly increased by the bulk deformation, which accelerates the void shrinkage on the bond interface. If the bul k is deformed, the contacting process is also affected by the asperity angle alpha0 due to surface waviness. When alpha0 < 30 deg, the bonde d area growth is mainly produced by the folding phenomena of the fayin g surfaces.