Thermo-Mechanical Coupled Numerical Simulation On The Interface Formation In Explosive Welding

Explosive welding is a kind of technology to produce composite plate, tube, bar and other composites. Microscopic characters of composites interfaces show the composites interfaces often appear as wave shape. There are severe plastic deformation, adiabatic shear bands, nanocrystals, amorphous and microdefects, such as as-cast microstructures, microcracks and micropores at interfaces of explosive welding. Interfacial plastic shearing phenomena at interfaces not only can influence the banding quality of composites products but also are focuses in explosion mechanics and impact dynamics. Some issues caused by high pressure and plastic shear action at explosive welding interfaces have not been a unified theoretical explanation by now. Such as interface wave formation mechanism, combining mechanism, the evolution of adiabatic shear band, et al. These interface phenomena are in a narrow area near combing interfaces. They are the typical hydro-elastic-plastic thermo-mechanical coupled problems closely relative to high temperature, high pressure, high strain rate and large plastic flow deformation. So the thermo-mechanical coupled calculation model is used to simulate the interface phenomena formation in this work. The main contents and conclusions are as follows:(1) The thermo-mechanical coupled calculation method suitable for explosive welding interface phenomena was established by using the smoothed particle hydrodynamics discrete method and basing on the hydro-elastic-plastic theory. And it was compiled into calculation program. Fourier heat conduction item was added into the control equations directly to consider thermo-mechanical effect. Cold energy was taken off from materical total internal energy to improve the accuracy of heating effect calculation. During the calculation, the "material constitutive properties influence caused by melting point pressure effect was also consided.(2) The nondimensional parameter of Fourier number was used to divide the welding interface transient heat conduction form by using compressible hydro-elastic-plastic thermo-mechanical smoothed particle hydrodynamics method. Research on interface temperature distribution, interface melting layer and jet were achieved under different Fourier number and various kinds of material explosive welding lower limit parameters. It was proved that explosive welding combination mechanism belonged to a special melting welding category.(3) The interface wave formation and micro jet injection process were simulated by the adiabatic smoothed particle hydrodynamics method.Simulation results showed the interface wave formation process was a special kind of interface stability phenomena, which could be consistent with Bahrani mechanism description. The relationship of interface wavelength and material strength was numerically analysed. The simulation results proved that elstic-plastic hydrodynamic theory model was suitable to solve problems of interface wave formation in explosive welding, and supported the viewpoint that material strength was a key factor during the interface wave formation.