Abstract:

As a discrete material, the granules medium shows some characteristics same with solid and liquid, other than that, it also has some unique characteristics. Just for that, the solid granule medium forming(SGMF) technology applies the solid granules as force-transmitting medium in the tube and sheet metal forming and has made some progresses. To improve the formability of tube and sheet metal, it is very important to give a control of the pressure distribution in inner surface, the force-transmitting characteristics of granules medium under high temperature is first studied. With a self-design uniaxial compression of solid granule medium, the distribution law of lateral pressures has been gained, and in combination with the nonlocal friction theory, an accurate force-transmitting model of granules medium has been built. Under this model, not only the force-transmitting law of granules medium based on nonlocal friction theory can be got but also the functional expression of axial transfer pressure can be deduced. The research result shows that: the lateral pressures of granules medium decreases regularly with the increase of force-transmitting distance, and they present a quadratic function relation. Also the axial transfer pressure of granules medium gradually decays with the increase of force-transmitting distance, and the theoretical value which has been got by considering non-local friction is closer to the experimental one than that has been got by local friction, while the radius of non-local friction area has less influence on the result.

Key words: lateral pressures, pressure-transfer characteristic, solid granule medium, nonlocal friction