Effect of non-uniform pressure on sheet formability in the bulging process of magnetorheological fluid pressure

The non-linearity of the space magnetic field results in the non-uniform distribution of the force transmission effect during the pressure forming of the magnetorheological fluid (MRF), which influences the forming ability, quality, and accuracy of the sheet. In this paper, the research results on the force state and formability of cone parts in the process of MRF pressure forming under different conditions show that: under the condition of high magnetic field intensity, the difference in the force state in different parts of cone parts is obvious. Under the condition of a 0.1-TB magnetic field, the non-uniform distribution characteristics of the stress state also change with an increasing forming height from 10 to 30 mm. The maximum pressure point is shifted from 8.93 MPa in the fillet region to 22.87 MPa in the free deformation region. Based on considering the factors of magnetic field distribution characteristics, the theoretical model of the relationship between the location of the spatial magnetic field and the thickness stress in the cone wall region is constructed, and the internal causes of the non-uniform distribution of pressure are further analyzed, which provides a theoretical basis for the precise control of the force transmission effect of magnetic media and the study of the pressure distribution characteristics in the forming process.