Finite element simulation of delamination growth in composite materials using LS-DYNA

A. M. Elmarakbi*, N. Hu, H. Fukunaga

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

78 Citations (Scopus)


In this paper, a modified adaptive cohesive element is presented. The new elements are developed and implemented in LS-DYNA, as a user defined material subroutine (UMAT), to stabilize the finite element simulations of delamination propagation in composite laminates under transverse loads. In this model, a pre-softening zone is proposed ahead of the existing softening zone. In this pre-softening zone, the initial stiffness and the interface strength are gradually decreased. The onset displacement corresponding to the onset damage is not changed in the proposed model. In addition, the critical energy release rate of the materials is kept constant. Moreover, the constitutive equation of the new cohesive model is developed to be dependent on the opening velocity of the displacement jump. The traction based model includes a cohesive zone viscosity parameter (η) to vary the degree of rate dependence and to adjust the maximum traction. The numerical simulation results of DCB in Mode-I is presented to illustrate the validity of the new model. It is shown that the proposed model brings stable simulations, overcoming the numerical instability and can be widely used in quasi-static, dynamic and impact problems.

Original languageEnglish
Pages (from-to)2383-2391
Number of pages9
JournalComposites Science and Technology
Issue number14
Early online date10 Feb 2009
Publication statusPublished - 1 Nov 2009


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