Study On Visualization Of Delamination On Set And Growth Process For Composite Advanced Grid Stiffened Plates

The numerical method and visualization have been developed to study delaminationonset and growth characteristics during post-buckling process for the delaminated compositeadvanced grid stiffened structures subjected by uniform axial compressive load. First, a finiteelement post-buckling analysis model was established based on the first-order sheardeformation theory in conjunction with Von-Karman nonlinear geometry theory; Second, thetotal energy release rate criterion combined with the virtual crack closure technique and theself-adaptive grid moving technology were used to analysis the detamination growth process,which considered the contact effect of front contours of the delamination At last, usingOpenGL to realize the process of the dynamic visualization. From numerical results for sometypical AGS plates, the effect of the style of the grid, the stacking sequence of the skin, thedelamination size and its location, and the ratio of rib's stiffness upon the characteristic strainvalues at delamination onset and unstable growth were discussed. In accordance with of theparameter investigations, the following conclusions were obtained:(1) The delamination growth behavior of composite grid stiffened plates (AGS) is verycomplicated, which is related with the style of the grid, the delamination position andits size, the stacking sequence of the skin, the ratio of rib's stiffness and so on,significantly.(2) The resisting delamination capability for Iso-grid stiffened structure is rather higherthan that for Ortho-grid stiffened structure.(3) The larger size of the delamination radius, the earlier appearance of the delaminationgrowth behavior, the faster entrance of unstable growth in the meantime.(4) The stacking sequence of the skin has more influence on behavior of the delaminationgrowth.(5) Enhance the rib's stiffness can increase the strain values at delamination onset andunstable growth. When the rib's stiffness reaches at a value, called the critical stiffness,enhancing the rib's stiffness can't increase the capability of resisting the delaminationonset and growth of plates.(6) Based on optimizing for the style of the grid, the stacking sequence of the skin and theratio of rib's stiffness, the resisting delamination capability of AGS structure has beenenhanced, dramatically. (7) The analysis method and conclusions provided in the paper would be valuable toestimate the load capability and optimal design for composite advanced grid stiffenedstructure.The research work of paper is one of sub-part for the project of the National NaturalScience Foundation in China "The Mechanism of Advanced Grid Structure (AGS) withDamage", Grant No. 10302004, and National Basic Research Program of China "New Theoryof Optimum Design for Extra-light Porous Materials and Their Structures", Grant No.2006CB601205.