Dynamic shear failure behavior of the interfaces in carbon fiber/ZnO nanowire/epoxy resin hierarchical composites

The shear failure behavior of the interfaces in carbon fiber (CF)/ZnO nanowire (ZnO NW)/epoxy resin hierarchical composites, and its dependency on strain rate, are investigated in this paper. A two-step hydrothermal method was conducted to grow a fibrous and vertically aligned ZnO NW layer onto the fiber surfaces, different nanowire lengths were obtained by varying the growth time. Quasi-static and dynamic interlaminar shear tests based on the modified v-notched beam specimens were carried out under different strain rates ranging from 2 × 10⁻⁴ s⁻¹ to 800 s⁻¹. The interlaminar shear strength (ILSS) was determined through inverse analysis based on experimental data and Finite element (FE) simulation. The results show that the ILSS has a positive strain rate dependency, which can be attributed to a change of failure mode of the epoxy matrix. Besides, longer and denser ZnO NWs shall provide better enhancement effects, because they could induce more microcracks in the epoxy matrix during the shear failure process and thus can bring more energy consumption.