Influence of Metal Layer Thickness on the Stress-Strain State and Strength of Metal Composite Cylinders Under Internal Explosion

The effect of metal layer thickness on the stress-strain state and strength of metal composite cylinders of constant total thickness under the action of internal dynamic pressure from an explosion of an explosive evenly distributed along the charge axis in an air medium with a constant relative charge mass ξ has been studied numerically. It is shown that the strength of shells with unidirectional circular reinforcement of the outer composite layer using composites with a low tensile strength boundary in the isotropy plane is determined mainly by wave processes along the thickness of the shell. For such a condition, its dependence on radial and axial stresses is much higher than on circular stresses, which are usually much larger for the first two components of the stress tensor. At constant ξ and total thicknesses H of the cylinder, the optimal ratio β_opt of the thickness of the metal layer h to H in terms of durability essentially depends on H and varies in the interval 0.15–0.35. The dependence β_opt on both H and ξ is non-monotone. It varies between 0.15 and 0.25 for a thin shell, 0.25–0.3 for a thick shell, and equal to 0.35 for a medium-thick shell. Due to wave processes along the radial coordinate, there may be cases where a thicker shell will be less strong than a thinner one with the same charge mass M and h/H. There may be cases where a change of M almost 1.5 times will have almost no effect on the strength of the cylinder. Significant influence on the strength of the shells have plastic irreversible energy losses in the inner steel layer, due to which the outer composite layer receives a shock wave of less intensity, and the strength of the object as a whole can be ensured.