numerical investigation of the effect of weld length and sheet thickness on stress and mechanical characterization of the diaphragm bellows

Diaphragm bellows are one of the essential parts in sealings and rotary equipment which are affected by their design parameters. this paper investigated the effect of weld length and plate thickness, on the mechanical characterization of diaphragm bellows. the mechanical characterization includes stress distribution, bellows deflection, spring constant, and fatigue life of the welded metal bellows.& finite element analysis was employed to study the effect of weld length and sheet thickness on the diaphragm bellows. in this regard, 12 models were designed based on experimental parameters. the number and combination of tests were designed by the response surface method and the results were evaluated by anova analysis. according to the results, if weld length and sheet thickness increase, the maximum stress and deflection of the bellows decrease, and the spring constant increases. the effect of sheet thickness on the behavior of the bellows is greater than weld length and it creates a limitation due to the effect on the spring constant. in the acceptable ranges of weld length and sheet thickness, based on fatigue analysis, the maximum life cycle is 1.2&×10⁶ and the minimum life cycle is 1.2×10⁶and the minimum life cycle is 1.7×10³.