Postbuckling behavior of segmented circular composite cylinders

The response characteristics of composite cylinders constructed in four circumferential segments are discussed. Two cylinder configurations, referred to as axially stiff and circumferentially stiff cylinders, are studied. Numerical results from STAGS finite element analyses are presented and include predicted radial displacements and selected stress resultants. Compressive loading into the postbuckling range by an axial endshortening is considered. The results show that, as the endshortening increases toward the buckling value, some segments of the cylinders begin to develop axial wrinkles, whereas other segments remain relatively unwrinkled. For the two cylinders considered here, the wrinkling of the segments is correlated with the level of axial stress resultant supported in the segment. Load drops of 20 and 57% for the axially stiff and circumferentially stiff cylinders, respectively, are predicted for levels of endshortening beyond the buckling values. The postbuckled cylinders are characterized by regions of large localized inward dimples and outward ridges in the radial displacement pattern. These regions are sites of large-magnitude axial and transverse shear stress resultants.