EXPERIMENTAL BUCKLING TESTS AND NUMERICAL ANALYSES OF STIFFENED CYLINDRICAL SHELLS IN COMPOSITE MATERIALS

摘要

The work presented in this paper is part ofrna larger research project aiming at improvingrnthe knowledge of the buckling behaviour ofrncomposite stiffened shell structures. Inrnparticular, it investigates experimentally andrnnumerically the buckling and post-bucklingrnphenomena of CFRP stiffened thin-walledrncylindrical shells.rnThe examined cylindrical shells,rnmanufactured and provided by AGUSTA, arerndesigned to work in the post-buckling field.rnIndeed, they present a first local buckling,rnlimited to the cylinder skin and later a globalrnbuckling, that corresponds to the collapse loadrnand involves the whole cylinder. The ratiornbetween the collapse load and the localrnbuckling load is about 4.rnThe experimental tests are performed underrnaxial compression. An equipment allows tornmeasure, by five laser displacement sensors,rnboth the initial geometric imperfections and thernbuckling pattern development on the specimensrninternal surfaces during the tests.rnThe experimental results are then comparedrnto those numerically obtained using the finiternelement code LS-DYNA. A slow dynamicrnanalysis was used to obtain the loaddisplacementrncurve and to follow the postbucklingrnpattern.