Buckling And Dynamic Stability Characteristics Of Damaged Stiffened Plates

As the development of the modern shipbuilding technology, buckling strength of marine structures needs to pay more and more attention with the widely application of high strength steel. A lot of marine accidents indicate that the deck may be buckling when a ship in a bad weather especially in the statement of sagging. During the time of ship construction and operation, some local components also need to evaluate the structural stability. Stiffened plate is the basic structure form of ships, so it is important to study the buckling characteristic of stiffened plate and shell.Corrosion, impact and fatigue are very common reason for structure failure among ships and other ocean structures due to the special working condition and natural environment. In some fields, the effect of corrosion, fatigue, impact and crack can be modeled as local reduction of material stiffness. The overall mechanics behavior can be changed due to these local damage, and finally lead to structure failure.This thesis introduces the damage mechanics into the static and dynamic buckling analysis of stiffened plate. Using Mindlin theory, we have built the four-node health and damage flat shell finite element, and then applied the finite element method to calculating the buckling and dynamic buckling behaviors. Isotropic damage elements are built by global and isotropic weakening of the stiffness. Anisotropic damage elements are built by using reduction coefficients for elasticity damages in x and y directions based on Kachanov's theory. The influence of parameters such as extent of damage, size of damage and position of damage are discussed to study their influence to structural bucking and dynamic stability characteristics. Finally, a computational method is given to analyze stability of damaged structure and demonstrated by some typical examples. The research of this paper do beneficial attempt in the stability evaluation of damaged structures.