Carbon fiber reinforced polymer (CFRP) composites exhibit outstanding properties, such as high strength, high stiffness, and lightweight. However, the structural performance of the CFRP is highly dependent on the interfacial bonding between the fiber and polymer matrix. Weak fiber/matrix adhesion can result in stress concentration, fiber pullout, delamination, and poor load-bearing capacity in the structure. Some techniques have been employed to improve the interfacial properties in the CFRP composites, including fiber surface modifications, utilizing functionalized materials, and growing nanomaterials on the fiber. It is reported that ZnO nanowires (NW) grown on carbon fiber laminates can improve the fiber-matrix adhesion bonding in the hybrid structures without affecting the strength of the fibers. It is essential to understand the atomic level interaction between fiber surface, ZnO NW, and polymer matrix for evaluating the interfacial properties of the hybrid CFRP composites. Atomistic simulation plays an important role considering the challenges of experimental analysis at the nanoscale. Molecular dynamics (MD) simulation is one of the most popular computational methods at nanoscale for analyzing the interface of the system by integrating Newton’s equations of motions overtime at the atomic scale. In this method, the forces of each atom are calculated based on the given initial position and velocity and their changes related to the provided interatomic potential.This paper reports an MD simulation study for evaluating the interfacial properties of ZnO NW hybrid CFRP composites. First, separate MD simulations are conducted to obtain the mechanical properties of cross-linked epoxy, carbon fiber sheet, and ZnO NW to evaluate the accuracy of the atomistic model. Tensile displacement is applied to each model, and the stress in the material is obtained as a function of strain. The elastic modulus for each material is calculated and compared with the literature. Next, a representative volume element (RVE) is simulated at the nanoscale containing a single ZnO NW vertically aligned on the carbon fiber surface and embedded in the epoxy matrix. Normal displacement load is applied to the carbon fiber sheet to separate it from the ZnO NW perpendicular to the fiber sheet. The traction-separation properties of the interface between fiber and the enhanced matrix are evaluated. The cohesive parameters, including the interfacial strength and the cohesive energy in the ZnO NW hybrid model, are compared with the base model (fiber and epoxy). The MD simulation results show a 98% improvement in the cohesive energy and 130% improvement in interfacial strength of the hybrid CFRP composites. This study demonstrates the promising effect of aligning ZnO on the fibers for enhancing fiber-matrix adhesion.&nbsp;

Atomistic Simulation of Interface Effects in Hybrid Carbon Fiber Reinforced Polymer Composites Incorporating ZnO Nanowires

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.