engleski

Mixed‐mode delamination of layered structures modeled as Timoshenko beams with linked interpolation

In this work, a finite-element formulation for modeling mixed-mode delami-nation in layered structures, consisting of two-node Timoshenko beam finiteelements with quadratic linked interpolation and corresponding 4-node inter-face elements is presented and compared to a more common approach wherelinear Lagrange interpolation is used. The principal novelty of the proposedapproach is that the vertical displacements of the beam elements, as well asthe transversal relative displacements of the interface elements, are interpolatedusing a quadratic linked interpolation that also takes into account the nodalcross-sectional rotations of the beam elements. At the same time, the axial dis-placements and cross-sectional rotations are interpolated using linear Lagrangepolynomials. A bilinear cohesive zone model is embedded in the interface finiteelements for delamination modes I and II. Numerical analyses based on theexamples from the literature with metal joints show that the formulation withquadratic linked interpolation improves the convergence and robustness of thesolution with respect to the approach with linear interpolation. On the otherhand, in case of composites with stiff adhesives this formulation exhibits a pecu-liar behavior with spurious oscillations of the normal interface tractions thatleads to a poor performance in mode-I and mixed-mode tests. This problem canbe easily solved by canceling the quadratic term in the interpolation functionand using the standard Lagrange interpolation in such cases.

cohesive-zone model ; delamination ; finite-element analysis ; interface element ; linked interpolation ; Timoshenko beam theory

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