Ultimate kinematic characteristics of composite solids accelerated by a magnetic field

The present paper considers the ultimate (under heating conditions) kinematic characteristics of composite solid bodies accelerated by unsteady magnetic-field pressure. The accelerated sheet comprises two layers: a layer of a composite material consisting of a mixture of two materials with different electrothermal properties and a homogeneous material layer. The electrical properties of the composite layer with the coordinate are varied along the coordinate by changing the volume concentration of its constituent materials. For an exponential magnetic field rise, an analytical solution is obtained for the problem of determining the optimum distribution of the volume concentration of the composite constituents for which there is a maximum increase in the ultimate velocity of the sheet. Numerical simulation showed that the distribution of the volume concentration obtained from analytical relations is also nearly optimal for pulse shapes of the accelerating magnetic field different from exponential ones. The possibility of considerably increasing the ultimate velocity through the use of composite layers compared to the ultimate velocities for the homogeneous materials constituting the composite is shown analytically and numerically.