Influence of simultaneous optimisation to enhance the stress-based fatigue life of bellows joint
Nitin D. Pagar
Abstract
Motion compensators utilized in process equipment pipe connections must be able to achieve maximum expansion-contraction cycle life with low stress levels. Due to bellows convolution complicated geometrical form and simultaneous necessity of optimum material flexibility and rigidity, the nature and magnitude of the stresses induced on the bellows convolution are multifaceted. Therefore, current research primarily focused on optimizing stress-based fatigue life and predicting cycles for a variety of bellows configurations. The integrated grey relational optimization methodology with principal components has been used. Experiment and FEA methods are employed to validate stress and fatigue equations derived from the Expansion Joint Manufacturing Equations (EJMA) data, which are then used to build experimental design models. The experimental PCA-GRG observed is 0.146 and the predicted PCA-GRG is 0.151, which is checked by the confirmatory test. It is shown that the life cycles calculated for the alternative optimal solution, as well as theL25 Taguchi run, ranged from 1.133 x 105 cycles to 9.083 x 105 cycles, which is the low-cycle, finite fatigue regime of the bellows material. This study enables the suitability of the PCA-GRG technique for realizing complicated relationships between desrete design factors and responses at multiple levels.