Evaluating the Local Strengh and Crack Resistance of an Glass Fiber Epoxy Composite in the Interlayer Tension and Shear Using a Finite-Element Model and Experimentally Determined Parameters of the Cohesive Zone

• Published in: Mechanics of composite materials 2023-09, Vol.59 (4), p.713-724
• Main Authors: Babaevsky, P. G., Salienko, N. V., Shatalin, A. A.
• Format: Article
• Language: English
• Subjects: Cantilever beams; Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Cohesion; Composite materials; Composites; Crack propagation; Epoxy resins; Finite element method; Fracture mechanics; Glass; Glass fiber reinforced plastics; Glass-epoxy composites; Interlayers; Laminar composites; Laminated materials; Linear elastic fracture mechanics; Materials Science; Mathematical models; Natural Materials; Polymer matrix composites; Solid Mechanics; Stress distribution; Structural members; Tensile stress; Three dimensional models; Ultimate loads
• ISSN: 0191-5665; 1573-8922
• DOI: 10.1007/s11029-023-10126-6

A systematic evaluation of the interlayer crack resistance in the modes I and II loadings of a glass fiber epoxy laminated composite by experimental and computational methods using the cohesive zone model was carried out. The local properties (the ultimate stress σ C , the maximum displacement δ max , and the specific work of fracture γ F ) of the cohesive zone were determined experimentally by the methods of separation and shear of the layer contact zone; the critical intensities of elastic energy release ( G IC and G IIC ) were found by the method of linear elastic fracture mechanics. Based on the experimental data obtained, the critical length of the cohesive zone was calculated by the Barenblatt micromechanical theory. A numerical evaluation of the crack resistance of a laminated composite under conditions of static loading in the modes I and II was carried out using 3D finite-element models of a double-cantilever beam and end-notched flexure specimens with an implemented cohesive zone obeying the exponential law. The optimal number of interface elements in the finite-element mesh was determined for the cohesive zone calculated based on experimental data, which ensured a sufficient accuracy of numerical calculating the ultimate load of the onset of crack growth and the stress distribution along the length of the cohesive zone with a minimum number of calculations. The approach proposed and the results obtained showed a good agreement between the calculated and experimentally determined characteristics of standard specimens of glass fiber epoxy composite and can be used to calculate the interlayer strength and crack resistance of structural members with a complex geometry made of layered polymer composites.