PSI - Issue 5

Etienne Bonnaud et al. / Procedia Structural Integrity 5 (2017) 310–317

317

Author name / Structural Integrity Procedia 00 (2017) 000 – 000

8

Figures 10a-b show a comparison between computed sequences and actual simulations for both maximal and minimal displacements. The best sequence turns out to be 1-2-4-5-3-6-8-7 and the worst sequence, 3-4-8-1-2-7-6-5. Agreement is rather good meaning that the suggested enhancement of the surrogate model works satisfactorily.

(a)

(b)

Fig. 10. Computed run rendering the largest (a) and smallest (b) vertical displacement. Comparison between estimate and simulation.

6. Conclusions

A surrogate model has been used to mitigate welding deformations in plates and pipes. For these geometries, addition of particular beads at particular positions in the sequence causes sudden stiffening which misleads the optimization process and gives erroneous predictions. This issue has been circumvented by assigning two different displacement values for certain pair combinations, depending on the welding history. The enhanced algorithms is then shown to accurately predict displacements and to find the bead sequence giving the smallest possible displacement. References Mochizuki, M., Hayashi, M., Hattori, T., "Residual Stress Distribution Depending on Welding Sequence in Multi-Pass Welded Joints with X-Shaped Groove," Journal of Pressure Vessel Technology, Vol.122, pp.27-32, 2000. Sattari-Far, I., Javadi, Y., "Influence of welding sequence on welding distortions in pipes," International Journal of Pressure Vessels and Piping, Vol.85, pp.265-274, 2008. Goldberg, D.E., "Genetic algorithms in search optimization and machine learning," Addison-Wesley Publishing Company, 1989. Kadivar, M.H., Jafarpur, K., Baradaran, G.H., "Optimizing welding sequence with generic algorithm," Computational Mechanics, Vol. 26, pp. 514-519, 2000. Voutchkov, I., Keane, A.J., Bhaskar, A., Olsen, T.M., "Weld sequence optimization: The use of surrogate models for solving sequential combinatorial problems," Computer Methods in Applied Mechanics and Engineering, Vol. 194, pp. 3535–3551, 2005. Asadi, M., Goldak , J.A., "Combinatorial optimization of weld sequence by using a surrogate model to mitigate a weld distortion," International Journal of Mechanics and Materials in Design, Vol. 7, 2011. Asadi, M., Alsoruji, G., "A method to define the best weld sequence using a limited number of welding simulation analysis," Proc. ASME PVP Conference, PVP2015-45556, 2015. Lindgren, L., Domkin, K., Hansson, S., "Dislocations, vacancies and solute diffusion in physical based plasticity model for AISI 316L," Mechanics of Materials, Vol.40, pp.907-919, 2008. Abaqus 6.13, "Analysis User's Manual", Dassault Systèmes Simulia Corp., Providence, RI, USA, 2014. Bonnaud, E., Gunnars, J., "Effect of in plane and out of plane bending on weld residual stresses," Proc. ASME PVP Conference, PVP2014-28737, 2014. Bonnaud, E., Gunnars, J., "Three dimensional weld residual stress simulations of piping butt welds - Influence of boundary conditions and start/stop positions on axisymmetry," Proc. ASME PVP Conference, PVP2016-63849, 2016.