A DEM model for visualising damage evolution and predicting failure envelope of composite laminae under biaxial loads

Abstract

A two dimensional particle model based on the discrete element method (DEM) is developed for micromechanical modelling of fibre reinforced polymer (FRP) composite laminae under biaxial transverse loads. Random fibre distribution within a representative volume element (RVE) is considered for the micromechanical DEM simulations. In addition to predicting the stress-strain curves of the RVEs subjected to transverse compression and transverse shear stresses against the experimental testing results and other numerical modelling results, the DEM model is also able to capture the initiation and propagation of all micro damage events. Fibre distribution is found to more significantly influence the ultimate failure of composite laminae under transverse shear, while it has much less effect on the failure under transverse compression. The failure envelope of composite laminae under biaxial transverse compression and transverse shear is predicted and compared with Hashin and Puck failure criteria, showing a reasonable agreement. The predicted failure envelope is correlated with the damage evolution and the quantitative analysis of failure events, which improves the understanding of the failure mechanisms.

Progressive failure analysis of CFRP composite laminates under uniaxial tension using a discrete element method

“…For the sake of simplicity, it was assumed that the shear strength of bonds is equal to its normal strength. 30 It is important to note that in the current study only tensile loading condition is considered to predict the damage initiation and progression in the composite laminates via the DEM model. The relationship between the ply angle and strength of angle-ply lamina of two different composite materials is plotted in Figure 7 with the Tsai-Hill failure criterion.…”

“…28 Apart from the FEM modeling, the discrete element method (DEM) has been introduced for modeling the damage propagation in the composite using a bondbased approach. Crack propagation in composite laminates and stress-strain curve were simulated under the transverse tensile loading by DEM in literature, [29][30][31][32] which suggests the capability of the DEM model for predicting the damage initiation, propagation until the final failure strength by providing more details such as crack density and stiffness reduction, etc. However, for a test specimen subjected to tensile loading, transverse cracks are usually initiated from the free edges of the specimen, then propagate almost instantaneously through the full width of the specimen in the case of monotonic loading.…”

3D particle models for composite laminates with anisotropic elasticity

“…Using the equation (22) and the stiffness relations between different balls, the following relationship between C ijkl and k n,t can be obtained…”

“…For a long time, numerical modelling of damage progression in FRP composite laminates has been reported using Finite Element Method (FEM) [10,11,12,13,14], Boundary Element Method (BEM) [15,16,17,18] as well as Discrete Element Method (DEM) [19,20,21,22]. The FEM and BEM methods are based on continuum mechanics and are capable of accurately predicting stress distribution as well as crack initiation, but the crack propagation and intersection is always challenging to deal with by these methods.…”

Experimental study and DEM modelling of bolted composite lap joints subjected to tension

“…The damage evolution and failure mechanism are complex multi-scale processes developing simultaneously from micro to macro scales, i.e., from debonding, cracking and fiber breakage to final failure. It has been widely recognized that the predictive failure models currently in use are not sufficiently accurate, especially when a FRP is under biaxial or triaxial forces, resulting in that most of FRP composite structures, e.g., bolted joints, have been conservatively designed under real loading conditions [18,31] . In order to have a better understanding of composite failure and take the full advantages offered by FRP in practical design, further investigations on the failure mechanism are demanded.…”