A method has been developed to analyze the impact response of triaxially braided carbon fiber composites, including barely visible damage. In the analytical model, the triaxial braid architecture is simulated using four parallel shell elements, each of which is modeled as a laminated composite. Because of the construction of the composite material, the resin regions between layers are weak areas in the material structure and can initiate damage by delaminating. To simulate these regions, each shell element is modeled as a homogeneous material with a zero-thickness cohesive zone (simulated with LS-DYNA’s tie-break contact) between the layers of braid. To accurately define the tie breaks used to model delamination, the resin materials’ cohesive zone must be defined. The length of the cohesive zone is calculated internally from parameters such as convergence scale factor, elastic modulus, peak traction, and strain energy release rate. To reliably model a cohesive zone, the zone should encompass three finite elements. This can lead to a reduced element length, which is impractical for many types of macroscale simulations. The convergence scale factor is used to efficiently model larger elements by applying a parametric reduction factor to effectively lengthen the cohesive zone while maintaining equivalent fracture energy.


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    Title :

    Macromechanical Approach to Modeling Barely Visible Damage in Braided Composites


    Contributors:

    Published in:

    Publication date :

    2013-08-02


    Size :

    72014-01-01 pages




    Type of media :

    Article (Journal)


    Type of material :

    Electronic Resource


    Language :

    Unknown