Accession Number:

ADA310579

Title:

Vibration Testing of Impact-Damaged Composite Laminates.

Descriptive Note:

Technical memorandum,

Corporate Author:

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH LEWIS RESEARCH CEN TER

Personal Author(s):

Report Date:

1989-06-01

Pagination or Media Count:

11.0

Abstract:

A new test is described that can be used to measure changes in the vibration properties of impact-damaged composite materials. Impact-induced delamination was observed to significantly affect natural frequencies of vibration and damping properties in cross-ply graphiteepoxy laminates. Natural frequencies are shown to drop by as much as half of their original value, and modal damping ratios can increase by a factor of up to eight when large amounts of damage are present. A simple finite-element model of the damaged impact specimens was used to predict the effect of delamination on certain vibration properties. A comparison of the finite-element calculations with the experimental measurements suggests that delamination was the dominant mechanism of flexural stiffness loss resulting from the transverse impact.

Subject Categories:

  • Laminates and Composite Materials
  • Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE