Simulation of impact failure of tubular samples made of composite material, depending on the loading rate

In this paper, a model that takes into account the dependence of strength properties on the damage rate is considered for modelling of the impact failure of composite materials. The constants of the material model are determined on the basis of experimental diagrams to compression and shear impact loading of unidirectional composite, which exhibit a nonlinear dependence on the strain rate. The proposed model is implemented to the Abaqus finite element modeling software for the case of a three-dimensional stress state. As an example of numerical modeling, we consider tubular composite specimens made of carbon fiber with an epoxy matrix and layers of different orientations, which are commonly used for determining of characteristics of impact energy absorption. Diagrams of impact loading of the considered tubular specimens are obtained. The influence of the chamfer (taper of the cross-section) on the edge of a tubular specimen on the impact loading diagram at the initial stage of the process, which serves as the initiator of crushing, is studied. The proposed approach allows us to estimate the magnitude of the peak of the amplitude associated with the crushing of the chamfer. In addition, at the initial stage of loading, maximum strain rates occur, which entails the hardening of the material, also expressed in the loading diagram as an increase in the amplitude. If the analysis neglects the effects associated with the strain hardening of the material and the geometry of the chamfer, the result may be expressed in an underestimation of the reaction, especially at the initial stage of the process. The absence of the described effects in the model of composite structures may lead to significantly incorrect results with complete failure with zero reaction. The developed approach is effective in the design and testing of damping elements made of composite material with properties that are sensitive to the loading rate.