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Karel Matous



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Multi-scale modeling of heterogeneous adhesives: Effect of particle decohesion


M.G. Kulkarni1, P.H. Geubelle1 and K. Matous1,2

1Department of Aerospace Engineering
2Computational Science and Engineering
University of Illinois at Urbana-Champaign
Urbana, IL 61801, USA.

Abstract


We examine the microscopic toughening mechanisms and their effect on the macroscopic failure response of heterogeneous adhesives made of stiff particles embedded in a more compliant matrix. The analysis relies on a multi-scale cohesive framework first described in Matouš et al. [Matouš, K., Kulkarni, M., Geubelle, P., 2008. Multiscale cohesive failure modeling of heterogeneous adhesives. Journal of the Mechanics and Physics of Solids 56, 1511–1533]. Two microscopic constitutive failure models are incorporated: an isotropic damage model to capture the fracture response of the matrix and a cohesive law to model the inclusion-matrix interfacial debonding. A detailed study of the RVE size is presented followed by a set of examples that illustrate the effect of filler size, volume fraction and particle–matrix interface properties on the macroscopic effective traction-separation law of heterogeneous adhesives.


Conclusions


A multi-scale cohesive scheme has been used to study the failure processes occurring at the micro-scale in heterogeneous adhesives and their effect on the macroscopic cohesive response. A study of the RVE size has shown that the microscopic domain width has to be about 2 or 3 times the layer thickness for the macroscopic response to be representative for the loading histories considered. The effect of particle size, volume fraction and particle–matrix interfacial parameters on the failure response and effective macroscopic properties has been analyzed. In contrast to the perfect particle–matrix interface case, where the failure is of adhesive–cohesive nature, a weak interface between the constituents generally results in a cohesive type of failure. The presented response curves (Figs. 5(b), 10(b), 11(b), and 12(b)) could be used as design diagrams to yield a potentially new heterogeneous adhesive with desired macroscopic properties.

Acknowledgment


The authors gratefully acknowledge the support from the National Science Foundation for this work under Grant No. CMS 0527965. The authors also acknowledge the support from the Center for Simulation of Advanced Rockets (CSAR) at the University of Illinois, Urbana-Champaign. Research at CSAR is funded by the US Department of Energy as a part of its Advanced Simulation and Computing (ASC) program under Contract No. B523819.
© 2009 UIUC and Dr. Karel Matous