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Piezoelectric stick–slip drive nanopositioners are of central importance in in situ SEM nanorobotic systems due to their high precise positioning, large stroke, high speed, and compact structure. However, the output velocity under high load will be seriously influenced. In this paper, a new piezoelectric stick–slip drive nanopositioner with large velocity under high load by introducing the adjust bolts to decouple the driving unit and moving unit is presented. A MATLAB simulation model has been created to optimize the nanopositioner for a certain velocity, and a FEM is used to confirm that the leaf hinge has sufficient stiffness. The size of the prototype is 30 × 32 × 25 mm3. Testing results indicate that the nanopositioner achieves a maximum velocity of 3.467 mm/s and a minimum resolution of 6 nm. When the load increases from 0.4 kg to 2 kg, the maximum velocities only decrease from 3.457 mm/s to 3.143 mm/s. The proposed piezoelectric stick–slip nanopositioner shows large velocity under high load.

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In order to investigate the deformation behavior of a plate during a vertical-horizontal rolling process, a thermo-mechanical coupling analysis is carried out by three-dimensional (3-D) rigid-plastic FEM to simulate the process. The metal flow and the shape evolution of the plate are focused during this investigation. The thickness and the width of the plate agree well with the measured values.

The process parameters including the mandrel structure of radial-axial ring rolling is in close relationship with the forming defects such as over-high axial spread and the folding defect in the connecting part of the big and small ring. In this paper, a 3D rigid-plastic and coupled thermal-mechanical finite-element model (FEM) of radial-axial ring rolling for large-scale T-sectioned ring was developed using commercial software of DEFORM-3D. By changing the chamfer radius of mandrel's work roll, the effects of mandrel structure on the height of axial spread which considerably affects the stability of the ring rolling process were investigated. The folding defect was also simulated. The numerical simulation results showed that with the decrement of the chamfer radius r, the metal increasingly accumulated in the big ring and the axial spread height increased. Consequently, the ring rolling process became unstable. Also, the folding angle augmented.