BUCKLING PERFORMANCE OF HYDROSTATIC COMPRESSION-LOADED 7-INCH DIAMETER THERMOPLASTIC COMPOSITE MONOCOQUE CYLINDERS

The general instability, or budding performance, of thick compression- loaded composite cylinders is not well understood. Few cylinders have been hydrostatically tested that exhibit a well-controlled buckling fa ilure. This work includes tile design, fabrication, and test results f or two monocoque cylinders tested in hydrostatic compression to measur e buckling performance. The design focused on assuring that buck-ling failure would occur before a strength failure. The analysis accounted for the effects of end cap design and boundary conditions. The two cyl inders were in-situ thermoplastic filament wound using AS-4 Graphite/P EKK and S-2 Glass/PEKK. Quality was excellent, with 1% void volume fra ction and negligible waviness. Both cylinders buckled elastically in t heir respective tests. The test results include acoustic emissions (AE ) and measured strains versus pressure. Experimental results show exce llent correlation with analytical predictions.