| The bellows are a kind of compensation component of the assembly andthermal displacement in pressure vessels and piping systems, which need to satisfythe requirements of strength and flexibility at the same time. It means when thecompressive strength is high enough, the stiffness should be as small as possible inorder to generate enough deformation.In order to optimize the structural design of bellows, the methods oftheoretical analysis, finite element numerical analysis and experimental verificationwere combined to analyze the influence of structural parameters on the bellows’performance from the following aspects.Firstly, for the multilayer U-shaped bellows without strengthening ring,theengineering algorithm was carried out to calculate the bellows stiffness,stress andsmooth stability when loading axial compressive displacement at room temperatureand high temperature. It was analyzed that the influence of the materials low andhigh temperature on the calculation, and the influence of the changes in waveheight, wave length and thickness on stiffness, stress and smooth stability.Secondly, for the multilayer U-shaped bellows without strengthening ring, thefinite element model was established to get the instability bellows deformation andstress distribution. It was also analyzed how the changes in wave height,wavelength and thickness influence the stiffness, stress and stability when loading axialcompressive displacement at room temperature and high temperature. The modelmade use of the axisymmetric solid elements, and the problem of contact betweenthe layers was considered.The stiffness test at room temperature and the flexion test at room and hightemperature were carried out by ground tests, which verified the rationality of thestructural design.By comparison of the three methods, the low of the influence of waveformparameters on bellows was summed. And the engineering algorithm of EJMA hasbeen improved too. |
