Proceedings Paper for the 61st AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference at AIAA SciTech 2021 Virtual Conference 11-21 January 2021

AIAA 2021-0275

Multiscale Modeling of Damage Response in Composites Reinforced with CNT Fibers

Neslihan Genckal, Stefan J. Povolny, Gary D. Seidel and Shengfeng Cheng
Virginia Polytechnic Institute and State University, Blacksburg, VA, 24061-0203, USA

This study shows the effect of CNT fibers on the material strength of epoxy-based composites. In order to simulate the material behavior properly, a hierarchical multiscale framework is employed. In the hierarchical multiscale framework, the information from all the RVEs in the subscales are passed to the next scale up in independent and off-line simulations. Due to the lack of spatial derivatives in its governing equations and therefore advantages in case of singularities, PD theory is used to solve the problem. First, the limitation of the horizon in the PD theory is overcome by a strategy used to have a free horizon. The method used is calibrating the critical stretch by using the macro level failure strain. A dogbone specimen is used for this purpose. The calibration is considered successful when the bond level failure stretch is within an acceptable error compared to the macro level strain. This is achieved after an iterative process. The calibration is done for only-epoxy and only-fiber materials, which are then used in the hexagonal and random RVEs. Different hexagonal RVEs of neat epoxy, 1, 5, 10 and 25% and random RVEs of neat epoxy, 0.5%, 1%, and 2% of VF of fibers are used. The effective material properties of the RVEs are obtained after tension tests done on the RVEs, which are then used in the macroscale compact tension specimen.