SEDL / STP / STP1059-EB / STP24116S

Three-Dimensional Analysis of Combined Free-Edge and Transverse-Crack-Tip Delamination

Fish, JC
McDonnell Douglas Helicopter Co., Mesa, AZ

Lee, SW
Associate professor, University of Maryland, College Park, MD

Pages: 16    Published: Jan 1990

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Abstract

The effects of combining a localized free-edge delamination with a transverse crack in [0/90ⁿ]^s (n = 1, 2, 3, and 4) glass/epoxy laminates are investigated. A three-dimensional finite-element model is used to calculate strain energy release rates associated with delamination growth. The effects of the assumed delamination size, transverse crack length, and thickness of the 90° sublaminate on the strain energy release rate are determined. Transverse cracking significantly increases the potential for delamination growth, raising the strain energy release rate by as much as two orders of magnitude. Furthermore, the introduction of a transverse crack changes the involvement of the different strain energy modes, so that the total strain energy release rate is dominated by the shearing modes with little opening mode involvement. The total strain energy release rate increases for laminates with thicker 90° laminates, but it is relatively insensitive to the size of the delamination.