Search

Abstract: The simulation of the delamination process in composite structures is quite complex, and requires advanced FE modelling techniques. Failure analysis tools must be able to predict initiation, size and propagation of delamination process. The objective of the paper is to present modelling techniques able to predict a delamination in composite structures. Four different ways of modelling delamination growth of a double cantilever beam test (DCB) are proposed. The first two approaches were based on a cohesive zone model: the interface being represented either by using delamination elements or non-linear springs. The idea of the third approach was to use a fracture mechanics criterion, but to avoid the complex moving mesh techniques it often implies. The interface between the two layers was simulated with solid elements representing the matrix, which were eliminated when their energy release rate exceeded the critical value. The energy release rate was computed using the virtual crack closure technique (VCCT). In the last approach, the interface behaviour was modelled by a tiebreak contact. Coincident nodes were tied together with a constraint relation and remained joined, until when the maximum interlaminar stresses was reached. Once this value was exceeded, the nodes associated with that constraint were released to simulate the initiation of delamination. The comparison of the results of the first three modelling techniques with experimental data showed that very good correlation was achieved. Poor results were obtained using tiebreak contact. It was due to the criterion used, since when the critical interlaminar stress was reached, the delamination was experienced before the critical energy release rate was reached. [Copyright &y& Elsevier]

The paper presents a new approach for failure modeling of a cellular structure manufactured with a 3D printing technology. For this purpose, the honeycomb topology was designed and fabricated using fused deposition modeling of ABSplus material. The proposed method was based on the tiebreak contact for connecting plastic joints with cell walls. Additionally, two methods based on constitutive models were also analyzed. In the first case, an elasto-plastic material model was adopted, whereas in the second case an elasto-visco-plastic material model with damage was included. Firstly, the mechanical properties of ABSplus material were determined and numerically correlated with experimental outcomes. Subsequently, a contact parametric study was performed, and the optimal contact parameters were evaluated. The quasi-static experimental compression tests were simulated using LS-Dyna software. The results of actual tests and numerical analyses with three different methods for honeycomb structure modeling were compared in terms of deformation, force history, failure behavior and energy absorption capabilities. It was shown that the contact-based method resulted an in an increase of the results quality with better reproduction of force characteristic and progressive failure behavior during the deformation process, compared to other two methods. Unlabelled Image • A new approach for failure modeling based on tiebreak contact algorithm is proposed • The proposed approach is compared with two standard constitutive model based methods • Contact parametric study is performed to assess failure parameters of tiebreak based algorithm • Crashworthiness properties of the Honeycomb cellular structure are investigated in experimental and numerical tests [ABSTRACT FROM AUTHOR]