| For the method of improving the plasticity of sheet metal, one is to perfect the materialsinherent nature such as crystal type, chemical composition and organization. On the otherhand, the plasticity of sheet metal can be improving by choosing external conditions such asdeformation temperature and deformation velocity et al. Meanwhile, the method of changingloading mode also can be used to improve the formability of sheet metal. Therefore, in thispaper, influences of the viscous medium loading modes of one-side, two-side and claddingsheet metal one-side on the formability of the sheet metal are studied by adopting viscousmedium pressure bulging. The influencing factors in forming process are concluded toachieve the goal of optimizing sheet metal loaing modes.Firstly, the bulging processes under different loading modes are theoretically analyzed.The influence of viscous medium non-uniform pressure distribution on geometrical shape,formability, stress and stain of bulging specimens in the process of one-side and two-sideloading are studied. On the base of the model of power hardening materials, the influence ofmaterial parameters of the cladding sheet metal on the formability of forming sheet metal inthe bulging process of one-side viscous medium loading of cladding sheet metal is confirmed.Secondly, the method of numerical simulation is used to analyse the bulging process ofsheet metal under different loading modes. Influences of viscous medium pressure fielddistribution and loading speeds in the one-side loading mode on the formability of sheet metalare obtained. Influences of the reversed pressure size and loading paths on the geometricalshape and wall thickness distribution of bulging specimens are studied by controlling thetwo-side viscous medium pressure, and the change rule of viscous medium pressure field isobtained. Influences of strength coefficient K, hardening exponent n and wall thickness t ofthe cladding sheet metal on the formability of forming sheet metal are studied in the bulgingprocess of one-side viscous medium loading of cladding sheet metal. On that basis, theformability of sheet metal under the three different loading modes is compared. Finally, experiments are carried out to verify the theoretical analysis and numericalsimulation. To aluminium alloy LF21as the research object, the influence of one-side viscousmedium loading speeds on the formability of sheet metal is studied, the influence of claddingsheet wall thickness on the formability of forming sheet metal is analysed by using SUS201stainless steel with different wall thickness as the cladding sheet metal. Meanwhile, choosingaluminium alloy LF21, LF2and stainless steel SUS201with same wall thickness as thecladding sheet metal to verify the influence of material parameters of the cladding sheet metalon the formability of forming sheet metal. The results show that the experimental results andthe theoretical analysis and numerical simulation results are identical with each other. |
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