Non-monotonous strengthening effects of polyurea layer on polyurea-aluminum composite plate subjected to blast of charge with prefabricated fragments

Abstract

In order to elucidate the failure characteristics and mechanism of polyurea-coated lightweight metal structures (taking 6063-T5 aluminum alloy plate as an example) under the combined actions of blast and high-speed fragment groups, a field test, micro analysis, numerical simulations, and theoretical analysis were conducted in this work. The results demonstrated interesting phenomena; notably, the emergence of non-monotonous strengthening effects of polyurea on composite structures was discovered. Under the examined test conditions, it was found that polyurea application on either the front or back aggravated damage of the substrate at a certain coating thickness rather than providing an enhancing protective effect. This was due to the lateral accumulation of stresses on the aluminum plate caused by the unilateral coating of polyurea, which limited the energy absorption effect. A certain polyurea coating thickness on both sides was found to be conducive to the glass transition of polyurea, which improved the protective performance of the target plate. This study could serve as a reference for the practical application of polyurea spraying technology under the combined actions resistance of metal thin-walled structures.