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Reinforced S-shape bellows are novel metal bellows with high pressure resistance. Displacement compensation ability is a key index in the design of metal bellows. Axial-tension-compression deformation and bending deformation are two typical displacement compensation forms. Thus, analysis of axial and bending stiffness is important in structure design.

In this study, theory analytics of axial tension and compression stiffness of reinforced S-shaped bellows structure is derived, and the load-displacement relationship during axial deformation is obtained by correcting the geometric parameters of waveform during axial tension and compression deformations. On the basis of them, the relationships of bending stiffness with axial tensile and compression stiffness under the action of bending loading are constructed, and thus, the theory analytics of bending stiffness is realized for S-shaped bellows.

This theory analytics is verified by comparing the results of theory analytics with those of numerical simulation for a few typical examples. An investigation on the axial and bending non-linear mechanical behaviors of multi-layer-reinforced S-shaped bellows was also carried out by numerical simulation and experiment, and the experimental results verified the reliability of the analysis method.

It is found that non-linearity behavior occurs greatly during the first loading course of reinforced S-shaped bellows, and the structure is strain-strengthened due to plastic deformation; however, stable stiffness characteristic is exhibited during the succeeding cyclic-loading course.

The purpose of this study is to campare the corrosion behavior of Az91 films and bulk sample, in the objective to provide reference for the corrosion resistance improvement of Mg alloys.

AZ91 films with various thickness values are produced by magnetron sputtering technique, and the corrosion behavior was characterized by immersion tests and electrochemical measurements.

The AZ91 films exhibited a preferred orientation with basal planes parallel to the surface and increased densification with the increase of thickness, and a superior corrosion resistance for the AZ91 films compared with the bulk sample.

The preferred (0002) basal planes in AZ91 films benefited the corrosion resistance and the nanoscale AZ91 films facilitated the development of a dense passivation film. Consequently, AZ91 film exhibited a superior corrosion resistance.