CIRCUMFERENTIAL STIFFENERS AS BUCKLE ARRESTORS IN LONG PANELS

It is well known that certain larger structures are susceptible to a t ype of collapse which starts locally but under favorable conditions ca n spread and has the potential of affecting the whole structure. The l owest load which can sustain this spreading of collapse (propagation l oad) is usually significantly lower than the critical buckling load of the geometrically intact structure. As a result, the option of avoidi ng the potentiality of propagating collapse by using the propagation l oad as the design criterion can result in significant penalties in cos t and weight. An alternative is to base the design on the critical buc kling load of the structure while including periodic stiffeners to arr est potential propagating collapse and keep its effect local. This pap er illustrates this new design philosophy through an example involving a long pressure-loaded panel with sparsely spaced circumferential sti ffeners cast in the role of buckle arrestors. An analysis is presented which models the process of quasi-static buckle penetration through s uch a stiffener. A general measure of arresting performance is defined , based on the maximum pressure experienced during the penetration pro cess. A general framework for establishing the dependence of the stiff ener arresting efficiency on the problem parameters is developed. Furt hermore, Fundamental concepts regarding limiting values for stiffener length and thickness are introduced, and results are presented which i ndicate that in this problem short, thick stiffeners provide the most arresting capacity for a given amount of stiffener material.