Crack Tip Plasticity in Nanomodified Thermoplastic Composites

Abstract

Nanomodified thermoplastic composites, reinforced with nanoparticles such as carbon nanotubes (CNTs), graphene nanoplatelets (GNPs), and silica, exhibit enhanced fracture toughness and energy dissipation through mechanisms including crack tip plasticity. Understanding crack tip plasticity is crucial for predicting fracture behavior and improving damage tolerance in structural thermoplastic composites used in aerospace, automotive, and defense applications. This study investigates crack tip plasticity in nanomodified thermoplastic composites under Mode I, Mode II, and mixed-mode loading. Polyetheretherketone (PEEK) and polypropylene (PP) matrices were reinforced with CNTs, GNPs, and silica nanoparticles at various loadings. Fracture tests included double cantilever beam (DCB), end-notched flexure (ENF), mixed-mode bending (MMB), and tensile tests at quasi-static and intermediate strain rates.