Impact Damage Tolerance of Composite Cylindrical Panels
Abstract
This thesis studied the impact damage tolerance of composite cylindrical panels subjected to low velocity impacts. Graphite/Epoxy and Kevlar/ Polyester panels were investigated. A simple method was devised to model the material as an orthotropic laminate. A nonlinear collapse analysis was performed to predict the strength of the undamaged panels. The sensitivity of the composite panel to small imperfections accounts for the difference between analytical and experimental loads. Imposing a transverse sinusoidal imperfection with a maximum amplitude equal to the thickness of one ply resulted in analytical loads that agreed with experimental loads to within 16% at worst. Graphite/Epoxy and Kevlar/Polyester curved panels were impacted with energies of 1-3 ft-lbs (velocities of 3.40-5.36 ft/sec). No damage occurred for impact energies below 1-3 ft-lbs, depending on the ply lay-up. The residual strength of the damaged panel was only 2-6% lower than the strength of undamaged panels. Ultrasonic C-Scan and microphotographs were taken of panels impacted with energies between 8-17 ft-lbs (velocities of 9.62-13.89 ft/sec) to investigate and characterize impact damage from the material response point of view. Even at low impact energies, C-scans and stereo X-rays show that internal damage occurs even though no exterior signs of damage are visible. The damage can be characterized by matrix cracking, delamination, and fiber breakage. Keywords: Tensile tests.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1989
- Accession Number
- ADA216401
Entities
People
- Eugene A. Senn
Organizations
- Air Force Institute of Technology