Strength Prediction for Multidirectional Open-Hole Composite Laminates under Dynamic Loading

  • Toenjes, Marco (Technical University of Munich)
  • Catalanotti, Giuseppe (Universidade de Evora)
  • Koerber, Hannes (Technical University of Munich)
  • Pohl, Christian (Technical University of Munich)
  • Drechsler, Klaus (Technical University of Munich)

In session: - Dynamics

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In recent years, energy based damage models started to replace semi-empirical methods for strength prediction and damage analysis of composite structures. Those models can produce physically accurate results inside non-linear finite element simulations at the cost of long simulation durations. Therefore there is additional need for fast strength prediction methods like the methodology proposed by Camanho et. al. [1]. Despite the unanimous consent that the behavior of composites may be strongly influenced by the strain rate [2, 3], most of the published modeling and experimental validation work was performed for quasi static loading. In this work the aforementioned methodology presented by Camanho et. al. [1] is extended to dynamic loading. The well-studied carbon-epoxy composite IM7-8552 is used to manufacture open-hole specimens with a quasi isotropic layup. Experiments are carried out under compressive and tensile loading. The quasi-static reference tests are performed on an electromechanical test machine and for the dynamic tests a Split-Hopkinson-Bar system is used. For each loading type three sizes of geometrically similar scaled specimens are tested to additionally study the size effect. For all tested configurations the strength is predicted with the finite fracture mechanics model using the ply crack resistance curves from Kuhn et. al. [2, 3]. The predictions and experimental results show good agreement. The present work indicates that quasi-static finite fracture mechanics theory is applicable for dynamic loading. It enables a quick prediction of the dynamic strength of multidirectional composite laminates which is superior to finite element models regarding runtime efficiency. In addition, the present work confirms the validity of the methodology used by Kuhn et al. [2, 3] to determine crack resistance curves of composites under dynamic loading.