An Investigation of Improved Welded Bellows for Positive Expulsion Applications.

摘要

An analytical and experimental program was conducted to determine whether the tilt-edge concept could be applied to the design of expulsion bellows. Such bellows must endure such large axial displacement that portions of the cross section are subjected to cyclic plastic strains. Expected cycle life is from 2,000to 20,000cycles. An analytical study was carried out using Battelle's computer codes NONLIN and NONLEP to determine bellows cross sections that gave low weld bead stresses and minimized the maximum stresses. A semi-elliptical cross section with 70degrees edge tilt was found to give the best overall stress distributions. Although the selected design proved to be difficult to fabricate,bellows were made and tested in low cycle fatigue. The fatigue tests proved that the design did give satisfactory fatigue life performance,even though shell buckling was observed in the leaves. (Author)