Accession Number:

ADA399377

Title:

A Predictive Methodology for Delamination Growth in Laminated Composites Growth in Laminated Composites. Part 2. Analysis, Applications, and Accuracy Assessment

Descriptive Note:

Final rept.

Corporate Author:

SYRACUSE UNIV NY DEPT OF MECHANICAL AND AEROSPACE ENGINEERING

Personal Author(s):

Report Date:

2001-10-01

Pagination or Media Count:

126.0

Abstract:

A nonclassical, energy release rate-based approach to predict delamination growth is described that overcomes the limitations of current, state-of-the art methodologies. First, two- and three-dimensional crack-tip elements are-introduced. When a classical, singular field-based mode decomposition procedure is used, the crack-tip elements are shown to predict the same values of energy release rate and mode mixity as two- and three-dimensional continuum finite element analyses for a wide variety of geometries, materials, lay-ups and loadings, including stiffened-skin construction typical to that used in aircraft construction. However, the crack tip element CTE analyses are considerably simpler and require orders of magnitude less development and execution time. Next, it is demonstrated that the CTE analyses may also be used to decompose the total energy release rate into nonclassical mode I, II, and III components. This nonsingular field NSF decomposition may be used, along with toughness versus mode mix data obtained from unidirectional laminates with midplane delaminations, to predict delamination growth with considerably better accuracy than the classical, state-of-the-art approach. This is due to the fact that the near-tip damage zone is sufficiently large in polymeric matrix composites to invalidate the classical assumptions, whereas the NSF mode decomposition is constructed in a manner that is insensitive to the details of this local damage state. This is demonstrated by applying both the classical and CTENSF approaches to make delamination growth predictions in four different graphite-reinforced composites, with matrices that include an epoxy, a toughened epoxy, a thermoplastic interlayer toughened epoxy, and a thermoplastic. For this portion of the study, only flat plate geometries were considered.

Subject Categories:

  • Laminates and Composite Materials
  • Manufacturing and Industrial Engineering and Control of Production Systems

Distribution Statement:

APPROVED FOR PUBLIC RELEASE