Contact analysis and experiment of delaminated cantilever composite beam

• Published in: Composites. Part B, Engineering Vol. 30; no. 4; pp. 407 - 414
• Main Authors: Yeh, M.-K., Fang, L.-B.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.01.1999; Elsevier
• Subjects: Applied sciences; C. Delamination; Composites; Contact analysis; Exact sciences and technology; Forms of application and semi-finished materials; Fracture mechanics (crack, fatigue, damage...); Fracture mechanics, fatigue and cracks; Fundamental areas of phenomenology (including applications); Physics; Polymer industry, paints, wood; Solid mechanics; Structural and continuum mechanics; Technology of polymers; Contact analysis; C. Delamination; Stratified material; Two dimensional model; Numerical method; Experimental study; Local effect; Composite material; Newton Raphson method; Finite element method; Testing equipment; Non linear effect; Delamination; Buckling; Damaging
• ISSN: 1359-8368; 1879-1069
• DOI: 10.1016/S1359-8368(99)00008-6

Cantilever composite beam with strip-type delamination under transverse loading was investigated analytically and experimentally. A two-dimensional (2D) nonlinear finite element code based on updated Lagrangian formulation was extended to analyze the behavior of the laminated beams under transverse loading and the local buckling phenomenon of the sublaminate in the delaminated region. The contact problem between the upper and the lower delaminated surfaces was dealt with the transformation matrix method, which satisfies the compatibility of displacements and can reduce the number of system unknowns. The resulting nonlinear system equation was solved by the modified Newton–Raphson method with a load-controlled scheme in the incremental solution procedure. This process was updated for the next increment when the contact condition was satisfied by iteration. The analytical results are improved when compared with the results without contact analysis. A tensile-test machine was modified with a set of fixture to record the load-displacement response of the delaminated cantilever beam; the response was in good agreement with the analytical ones. The results show that the size of the delaminated region had no significant influence on the stiffness of the laminated beams with or without local buckling. The stiffness of the delaminated beams reduced as the delaminated region located further deeper in the thickness direction. The normal and tangential contact forces on the surface of the delaminated region varied along the delaminated length with maximum values at the point most close to the fixed end.