Numerical investigation to prevent crack jumping in Double Cantilever Beam tests of multidirectional composite laminates

• Published in: Composites science and technology Vol. 71; no. 13; pp. 1587 - 1592
• Main Authors: Sebaey, T.A., Blanco, N., Lopes, C.S., Costa, J.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 09.09.2011; Elsevier
• Subjects: Applied sciences; Asymmetry; B. Delamination; B. Fracture toughness; C. Finite Element Analysis (FEA); Cantilever beams; Crack propagation; Exact sciences and technology; Forms of application and semi-finished materials; Fracture mechanics; Fracture toughness; Jumping; Laminates; Polymer industry, paints, wood; Stiffness; Technology of polymers; Thermal residual stresses; Thermal residual stresses; B. Fracture toughness; B. Delamination; C. Finite Element Analysis (FEA); Thermal stress; Stacking sequence; Laminate; Fiber reinforced material; Epoxy resin; Theoretical study; Mechanical properties; Mineral fiber; Modeling; Composite material; Crack propagation; Finite element method; Numerical simulation; Delamination; Residual stress; Double cantilever beam; Carbon fiber
• ISSN: 0266-3538; 1879-1050
• DOI: 10.1016/j.compscitech.2011.07.002

► We analyse the effect of multidirectional interfaces in composite delaminations. ► Propagation of delamination in multidirectional interfaces is studied numerically. ► Thermal effects and residual stresses affecting delaminations are also considered. ► Tendency to crack branching or ply change is also considered with failure criteria. ► Beam stiffness is determinant to avoid crack branching or ply change. During the experimental characterization of the mode I interlaminar fracture toughness of multidirectional composite laminates, the crack tends to migrate from the propagation plane (crack jumping) or to grow asymmetrically, invalidating the tests. The aim of this study is to check the feasibility of defining the stacking sequence of Double Cantilever Beam (DCB) specimens so that these undesired effects do not occur, leading to meaningful onset and propagation data from the tests. Accordingly, a finite element model using cohesive elements for interlaminar delamination and an intralaminar ply failure criterion are exploited here to thoroughly investigate the effect of specimen stiffness and thermal residual stresses on crack jumping and asymmetric crack growth occurring in multidirectional DCB specimens. The results show that the higher the arm bending stiffness, the lower the tendency to crack jumping and the better the crack front symmetry. This analysis raises the prospect of defining a test campaign leading to meaningful fracture toughness results (onset and propagation data) in multidirectional laminates.