Theoretical and experimental study of bistable symmetric shells built by locally nanostructuring an isotropic plate

A new bistable symmetric isotropic shell is proposed and studied by using nano-technique, surface mechanical attrition treatment (SMAT), to locally treat a rectangular region within a plate. Plastic deformations accumulate in the treated region with the impacts from randomly fast moving balls during the process. The impacts also induce nanotwins and mesh the grains of the material into nanoscales, which largely increase the elastic deformation ability of the processed plate. With sufficient plastic deformations accumulated and stretching the plate under the constraint from the untreated region, the induced residual stress field buckles the plate to hold two different stable configurations and, thus, the bistable characteristic is generated for the nanostructured plate. A numerical model is developed to predict the stable configurations with verification by experiments. The parameters to design the stable configurations of the bistable shells are systematically discussed experimentally and numerically.