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This and the next two slides are from:
R. Degenhardt, H. Klein, A. Kling, H. Temmen, R. Zimmermann (DLR Institute of Structural Mechanics, Braunschweig, Germany), “Buckling and postbuckling analysis of shells under quasi-static and dynamic loads”, undated pdf file; no references; possibly created about 2005.
Subject structures are stringer-stiffened CFRP cylindrical panels under axial compression and in-plane shear.
Analysis is by ABAQUS finite element models.
SUMMARY: Numerical simulations of the buckling and the geometrically highly non-linear postbuckling behavior of CFRP curved panels and cylinders under quasi-static loading, based on the Finite Element (FE) method, are performed. For curved panels the numerical results are in excellent agreement with results obtained by physical tests, whereas for cylinders testing was not carried out. However, the lessons learned for panel simulation are also valid for cylinders, in particular, as with cylinders, no influence of lateral edges has to be taken into account. With the FE simulations the computing time is extremely high, and development of fast procedures for use in the design stage is desirable. A concept for such a procedure based on regularly updated shape functions is established.
Development of fast procedures is also needed for the simulation of the buckling behavior of dynamically loaded fibre composite shells. However, this is a more fundamental topic than that of postbuckling, and the phenomenon of critical interaction leading to buckling load reduction, which is of basic importance for the devopment of appropriate fast simulation procedures, was not understood well. Therefore, a multitude of time consuming parametric FE simulations are conducted. The results indicate that the occurrence of a longitudinal axial mode and its coupling with a bending mode is the physical pre-condition for critical dynamic behavior. Based on this insight, a concept for the development of a fast procedure is generated. The buckling test facility is made ready for tests with impulsive loading by application of a new hydraulic system and the development of its necessarily complex control.
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