Delamination of Composite Cylinders
The delamination resistance of filament wound glass/epoxy cylinders has been characterized for a range of winding angles and fracture mode ratios using beam fracture specimens. The results reveal that the delamination fracture resistance increases with increasing winding angle and mode II (shear) fraction (GΠ/G). It was also found that interlaced fiber bundles in the filament wound cylinder wall acted as effective crack arresters in mode I loading. To examine the sensitivity of delamina-tion damage on the strength of the cylinders, external pressure tests were performed on filament-wound glass/epoxy composite cylinders with artificial defects and impact damage. The results revealed that the cylinder strength was insensitive to the presence of single delaminations but impact damage caused reductions in failure pressure. The insensitivity of the failure pressure to a single delamination is attributed to the absence of buckling of the delaminated sublaminates before the cylinder wall collapsed. The impacted cylinders contained multiple delaminations, which caused local reduction in the compressive load capability and reduction in failure pressure. The response of glass/epoxy cylinders was compared to impacted carbon reinforced cylinders. Carbon/epoxy is more sensitive to damage but retains higher implosion resistance while carbon/PEEK shows the opposite trend.
KeywordsHoop Stress Impact Damage Diameter Cylinder Composite Cylinder Large Cylinder
This research has been conducted within a cooperative program between the French Oceanographic Research Organization, IFREMER, and the Department of Mechanical Engineering at Florida Atlantic University (FAU). The participation of FAU in this program is sponsored by the Office of Naval Research (ONR) with Dr. Yapa D. S. Rajapakse as the program monitor. The research of F. Ozdil and Xiaoming Li is greatly appreciated. Additional results from IFREMER studies and the European EUCLID RTP 3.8 project are also presented. Technical support in the pressure test programme from members of the Materials and Structures group at IFREMER, P. Warnier, E. Person, L. Riou, A. Deuff and J J. Le Roy, is gratefully acknowledged. Thanks are due to Mr. Josh Kahn, Ms. N. Carr, and Mr. M. Farooq for help with preparation of this chapter.
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