Accession Number:

ADA390067

Title:

Dynamic Cracking and Energy Absorption in Laminates Containing Through-Thickness Reinforcement

Descriptive Note:

Final rept. 30 Aug 1999-28 Feb 2001

Corporate Author:

ROCKWELL INTERNATIONAL CORP THOUSAND OAKS CA SCIENCE CENTER

Personal Author(s):

Report Date:

2001-04-18

Pagination or Media Count:

102.0

Abstract:

We report several fundamental results in the delamination resistance of through-thickness reinforced structures under dynamic load conditions. The main results are 1 An elaborate micromechanical model shows how a bridging tow should behave if it is initially inclined to the fracture plane and subject to mixed mode quasistatic loading 2 A bridging law for fiber reinforced composites under dynamic crack propagation conditions has been derived. INertial effects in the mechanism of fiber pullout during dynamic propagation of a bridged crack are critically examined for the first time. 3 The dynamic delamination cracking behavior and the energetics of crack growth in through thickness double cantilever beam specimens has been analyzed. Steady state crack growth is attainable provided certain conditions are satisfied. Guidelines for design of experiments to probe the efficacy of bridging on improving the dynamic fracture toughness of through thickness reinforced structures are established. In summary, these results form a sound fundamental basis for design and life prediction of through thickness reinforced structures.

Subject Categories:

  • Laminates and Composite Materials

Distribution Statement:

APPROVED FOR PUBLIC RELEASE