Effect of Low-Velocity or Ballistic Impact Damage on the Strength of Thin Composite and Aluminum Shear Panels
Abstract
Impact tests were conducted on shear panels fabricated from 6061-T6 aluminum and from woven-fabric prepreg of DuPont Kevlar fiber/epoxy resin and graphite fiber/epoxy resin. The shear panels consisted of three different composite laminates and one aluminum material configuration. Three panel aspect ratios were evaluated for each material configuration. Composite panels were impacted with a 1.27-cm diameter aluminum sphere at low velocities of 46 m/sec and 67 m/sec. Ballistic impact conditions consisted of a tumbled 0.50-caliber projectile impacting loaded composite and aluminum shear panels. The results of these tests indicate that ballistic threshold load (the lowest load which will result in immediate failure upon penetration by the projectile) varied between 0.44 and 0.61 of the average failure load of undamaged panels. The residual strengths of the panels after ballistic impact varied between 0.55 and 0.75 of the average failure strength of the undamaged panels. The residual strengths of the panels after ballistic impact varied between 0.55 and 0.75 of the average failure strength of the undamaged panels. The low-velocity impacts at 67 m/sec caused a 15- to 20-percent reduction in strength, whereas the impacts at 46 m/sec resulted in negligible strength loss. Good agreement was obtained between the experimental failure strengths and the predicted strength with the point stress failure criterion. Keywords include: Composite materials; Shear panels; Damage tolerance; Low-velocity impact; Ballistic damage; Postbuckling; Helicopter; and Fuselage.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1985
- Accession Number
- ADA155925
Entities
People
- Gary L. Farley
Organizations
- National Aeronautics and Space Administration