The objective of this research was to establish a test methodology to characterize dynamic properties for 2D tri-axial braided composites under impact conditions for applications in advanced jet engine containment structures. New generations of jet engines will be equipped with composite containment cases to significantly reduce weight while maintaining or increasing the impact strength. As a result jet engines will offer greater safety and reduced fuel consumption, while remaining cost effective.
In this study, the T700S/PR520 Graphite/Epoxy system was selected. Impact tests were conducted using gas guns that generate velocities that are equivalent to blade fragments impacting jet engine containment cases during a blade out. A specially formulated gelatin projectile with a cylindrical shape was used to impact square composite plates rigidly supported at all four boundaries in a picture frame fixture. Fabrication of the test articles was consistent with the process used for the jet engine containment structures. High speed cameras were used to measure the projectile velocity, observe projectile and plate deformations, as well to capture images for digital image correlation post processing to measure dynamic in-plane strains and out-of plane displacement fields. Repeated tests were conducted to identify threshold, visible damage, and damage initiation velocities. The methodology and tests results presented in this thesis are unique to braided composites and provide a test methodology needed for composite material model development, and numerical simulation validations. The same test methodology can be used with similar composite systems, as well as systems exposed to aging elements in the future.