General instability of ring-stiffened cylindrical shells under external pressure

Recent advances of numerically controlled machining enable the accurate estimation of buckling pressure of stiffened cylindrical shells by experiments. Machined models can be regarded as perfectly cyclindrical shells, and the validity of modeling for numerical methods is confirmed by comparing theoretical results with experiments. In the present paper, the so-called general instability of stiffened cyclindrical shells is investigated. Actual shells are fabricated by welding, and have inevitable initial deflections which result in reduction of buckling pressure due to imperfection sensitivity. The reduction factor is discussed in relation to the evaluation method of initial deflections in actual shells.