Mixed Bending-Tension (MBT) test for mode I interlaminar and intralaminar fracture

• Published in: Composites science and technology Vol. 72; no. 9; pp. 1049 - 1055
• Main Authors: Macedo, F.S., Pereira, A.B., de Morais, A.B.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 21-05-2012; Elsevier
• Subjects: A. Polymer–matrix composites (PMCs); Adhesive bonding; Applied sciences; B. Delamination; B. Fracture toughness; Bonding; C. Finite element analysis (FEA); Carbon; Consistency; Crack propagation; Exact sciences and technology; Forms of application and semi-finished materials; Fracture mechanics; Interlaminar; Laminates; Polymer industry, paints, wood; Technology of polymers; A. Polymer–matrix composites (PMCs); B. Fracture toughness; C. Finite element analysis (FEA); B. Delamination; Laminate; B Delamination; Unidirectional fiber material; Bending tensile strength; Epoxy resin; Mechanical properties; Experimental study; Mineral fiber; Modeling; Composite material; Fracture toughness; Finite element method; B Fracture toughness; C Finite element analysis (FEA); A Polymer-matrix composites (PMCs); Measurement method; Delamination; Carbon fiber
• ISSN: 0266-3538; 1879-1050
• DOI: 10.1016/j.compscitech.2012.03.023

A new Mixed Bending-Tension (MBT) test is proposed for mode I fracture of laminated composites. The MBT specimen consists of a relatively small pre-cracked laminate adhesively bonded to pin-loaded steel beams. This design reduces significantly the bending stresses that prevent successful application of DCB tests to certain laminates. The MBT was here applied to carbon/epoxy unidirectional [0°]26 and [90°]26 laminates with starter delaminations. Interlaminar initiation GIC values of [0°]26 laminates agreed well with previous DCB test results, while [90°]26 laminates exhibited 50% higher values. Significant lengths of fairly planar intralaminar crack propagation were seen in the latter laminates. The results showed a fibre bridging related R-curve, which was more pronounced in [0°]26 laminates. The consistency of the present results indicates that the MBT opens new possibilities for the interlaminar and intralaminar mode I fracture.