The failure process of composite laminate under quasi-static or fatigue loading involves sequential accumulation of intra- and interlaminar cracking. Matrix cracking parallel to the fibres in the off-axis plies is the first damage mode observed. It triggers development of other harmful resin-dominated modes such as delaminations. In this chapter, analytical modelling of crack-induced delaminations in composite laminates subjected to general in-plane loading is presented and discussed. A two-dimensional shear lag analysis is used to determine ply stresses in a representative segment and the equivalent laminate concept is applied to derive expressions for mode I and mode II and the total strain energy release rate associated with uniform local delaminations. These expressions could be used with appropriate fracture criteria to estimate the onset of local delamination in an already cracked off-axis laminate. Dependence of strain energy release rate on crack density, delamination area and ply orientation angle in unbalanced symmetric laminates is examined and discussed, and the effect of crack-induced delamination on the laminate stiffness is predicted.
|Title of host publication||Structural Durability and Durability of Advanced Composites|
|Subtitle of host publication||Innovative Modelling Methods and Intelligent Design|
|Editors||P.W.R. Beaumont, C. Soutis, A. Hodzic|
|Number of pages||34|
|Publication status||Published - 2015|
Bibliographical noteAcknowledgements: Financial support of this research by the Engineering and Physical Sciences Research Council (EPSRC/GR/L51348) and the British Ministry of Defence is gratefully acknowledged.
- Composite laminate
- Micromechanical modelling
- Stiffness degradation