Nanostructured bistable and multistable metal shells are derived from the independent intellectual property rights of the CASM, by using a large number of random high-speed moving balls to bombard the surface of the shell material in localized regions, introduce high-density nanotwin in the shell material and refine the metal grains into nano size, thereby significantly improving the yield strength of the local nanostructured material and increasing the elastic deformation ability of the processed shell. At the same time, a large number of high-speed bombardments gradually accumulate a large number of plastic deformations on the front and back of the shell material, stretching the locally treated region under the constraint of the area without treatment, and the lateral buckling deformation of the shell happens in the two directions under the compressive stress state, which increases with the increase of the further nanostructuring treatment. Due to the significant increase in the elastic deformation ability of the nanostructured metallic material, the two stable post-bulked states can be elastically switched under the action of external load, so as to achieve the local bistable effect.

Multistable shells can be constructed by nanostructuring multiple local regions in the same shell. The coupling and superposition of multiple local bistable effects on the same shell realize the designable morphology of the multistable shell, and its multiple stable states are related to the shape, size, nanostructuring degree and distribution of the local nanostructured regions. In order to better design the multistable shell, the research team also undergo mechanical plastic reprocessing of the nanostructured shell, such as plastically folding or overall plastic bending deformation, etc. The multistable shell after mechanical reprocessing can maintain the multistable characteristics after the overall deformation, that is, the stress field in the local nanostructured region will not lose the bistable effect due to the superposition of residual stress fields generated by the future plastic processing.

The research team established a corresponding theoretical model to predict and guide the stable states of the multistable shells. After the theoretical model study and the preparation process of the multistable metal shells, the research team carried out the study of the morphological conversion characteristics of the local bistable region under the action of external point, line and surface loads, and obtained the corresponding optimal arrangement form of the external loads that stimulated its morphological conversion. The research team further proposed the remote wireless controllable morphological conversion approaches for the bistable and multistable shells using mechanical drive rods and pneumatic suction cups, and developed the corresponding driving system to achieve the morphological conversion of the bistable and multistable metal shells.

The research team applied the bistable and multistable nanostructured shells to underwater equipment and variable wings. An underwater profile water quality monitoring system and a variable wing structure model were realized. The corresponding technique has won the special gold medal of the China University Science and Technology Achievement Fair, the gold medal of the China (Shanghai) International Invention and Innovation Exhibition, and the gold medal of the "Invention and Entrepreneurship Award Project Award" of the National Invention Exhibition.

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