Mixed-mode delamination growth of laminar composites by using three-dimensional finite element modeling

• Published in: Fatigue & fracture of engineering materials & structures Vol. 26; no. 6; pp. 543 - 549
• Main Authors: SILVA, A., MOREIRA DE FREITAS, M. J.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Oxford, UK Blackwell Science, Ltd 01-06-2003; Blackwell Science
• Subjects: Applied sciences; composites; delamination; Exact sciences and technology; Metals. Metallurgy; mixed mode delamination; Powder metallurgy. Composite materials; Production techniques; strain energy release rate; Finite element method; composites; mixed mode delamination; Strain energy; Mechanical properties; Laminated plate; strain energy release rate; Delamination; Modeling; Composite material; Crack propagation
• ISSN: 8756-758X; 1460-2695
• DOI: 10.1046/j.1460-2695.2003.00643.x

ABSTRACT Delamination is one of the most frequent failure modes in laminated composites. Its importance is crucial, because a delamination can occur in the interior of a panel without any noticeable damage on the surface, drastically reducing its strength and stiffness. A study has to be made on critical dimensions of delaminations and their shape, through the calculation of the strain energy release rate (SERR), G. This study was performed numerically, for a given geometry, with varying loads and shapes of delamination, in pure and mixed‐mode propagation. All numerical values were obtained with three‐dimensional finite element (FE) analyses from a commercial package. The use of three‐dimensional analyses in simple geometries helps establish the basis for the more complex ones, and the correspondence with the usual analytical or numerical bi‐dimensional plane‐strain analysis. The conclusions were (a) G is not constant along the crack tip, even for mode I propagation and straight crack tip; (b) the mean value of G obtained from a three‐dimensional analysis equals the value obtained in bi‐dimensional plane‐strain analysis; (c) in mixed‐mode propagation, the method exhibits a good correlation with experimental results and (d) the shape and mode partitioning of the SERR depend not only on the loading, but also on the shape of the crack front.