IWPDF2023

Formulation of a Bilinear Traction-Separation Interface Law in Bound ary Elements with Homogenization

A. A. Akay 1 , ∗ , S. Göktepe 2 , E. Gürses 1

1 Department of Aerospace Engineering, Middle East Technical University, Ankara 06800, Turkey 2 Department of Civil Engineering, Middle East Technical University, Ankara 06800, Turkey

∗ aakay@metu.edu.tr

Keywords: Boundary element method, bilinear interface modeling, homogenization

Similar to most conventional composite materials, the interface is generally the weakest part of nanocomposites. For this reason, the behavior of the reinforcement-matrix interface is critical for determining the strength of nanocomposites. Especially in nanocomposites, if no special precau tions are taken, the matrix consisting of nano-reinforcements and polymer chains are bound to each other by weak van der Waals interactions and electrostatic interactions. As a result, in most nano-composites under loading, damage first begins as separation at the interface. This study focuses on a key aspect of modeling polymer nano-composites: the interface between the inclu sion and the matrix. First, the alternative boundary conditions of homogenization are presented and then implemented in the boundary element method. Afterward, a bilinear interface law [1] between inclusion and matrix is defined in the boundary element-based homogenization method. The homogenized stress responses of a heterogeneous Representative Volume Element (RVE) undergoing debonding are compared with numerical studies from the literature. RVEs, including both single and multi-inclusions, are studied. Comparisons are made with the studies based on modeling interfaces using micromechanics and Mori-Tanaka-based approaches [2], and boundary element method-based approaches [3]. A good agreement is observed between results. References [1] H Tan, C Liu, Y Huang, and Philippe H Geubelle. The cohesive law for the particle/matrix interfaces in high explosives. Journal of the Mechanics and Physics of Solids, 53(8):1892-1917, 2005. [2] HM Inglis, PH Geubelle, K Matous, H Tan, and Y Huang. Cohesive modeling of dewetting in particulate composites: micromechanics vs. multiscale finite element analysis. Mechanics of Materials, 39(6):580-595, 2007. [3] Zhipeng Wu, Qinye Lin, and Yongqiang Chen. Application of fast multipole boundary element method for two-dimensional nonlinear interface debonding of particulate composites. Engineering Analysis with Boundary Elements, 113:72-81, 2020.

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