A coupled experimental and numerical method to determine the fracture toughness

  • Ma, Dayou (Politecnico di Milano)
  • Verleysen, Patricia (Ghent University)
  • Giglio, Marco (Politecnico di Milano)
  • Manes, Andrea (Politecnico di Milano)

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As an essential component for composite materials, polymer materials have attached much attention rencently. During their life, they may be exposed to extreme loading conditions. Thus, an investigation into their dynamic mechanical properties is of great importance for their applications. In the current work, the dynamic fracture properties of RTM6 epoxy resin have been studied with both experimental and numerical methods. Using a modified split Hopkinson compression bar system, three-point bending, dynamic fracture tests with notched samples were carried out. High-speed camera recording and the digital image correlation technique were used to monitor the fracture process. However, the determination of related fracture parameters, like energy release rate, and an accurate depiction of the actual loading conditions, such as the strain rate at crack tip, is not straightforward and requires significant experimental efforts, due to the complicated loading conditions in the fracture tests. Therefore, a numerical model based on the peridynamic method has been built to replicate the experimental fracture process of samples in a “virtual test” fashion. After a preliminary validation of the modelling approach with experimental data, the energy release rate of the material under dynamic conditions is obtained exploiting inverse method, while the strain rate at crack tip can be calculated from the numerical results. Using the coupled experimental and numerical method, the dynamic fracture properties of RTM6 can be obtained. More specifically, the relationship between strain rate and energy release rate can be built for further applications, which can be applied on nanocomposites.