The influence of weld-induced residual stresses on the buckling of cylindrical thin-walled shells

摘要

The load carrying behaviour of cylindrical thin-walled shell structures under axial load is strongly dependent on imperfections invariably caused by manufacturing processes. Axisymmetric imperfections have been known to result in particularly severe reductions in strength. Imperfections in the vicinity of circumferential welds in steel silos and tanks fall into this category and therefore deserve special attention. Finite element models were used to analyse imperfect cylindrical shells and special care was taken to model the weld4nduced imperfection. The geometry was calibrated against data gained from measuring such imperfections on existing silos, and residual stresses were taken into account. Interaction with global imperfections in the cylindrical shape was investigated. A number of parameters were evaluated in respect to their influence on the buckling behaviour of the modelled cylinders. The load carrying behaviour of the investigated models was found to be strongly dependent on the depth of the local imperfection. Residual stresses were found to have only a small influence on the buckling load. Shape of the weld depression and properties of the welding material also contributed to small variations in the buckling behaviour.