Shear strength of steel fiber/polyepoxide resin interface using single fiber pull-out tests

Abstract

Thermoset polymer has considerable useful properties in structure, energy and marine industries. Polyepoxide or epoxy is widely used in composite matrix materials, and therefore, the adhesion between the reinforcement and the matrix is crucial. In order to enhance the adhesion conceptually, single steel fiber reinforcement polymer (SRP) was used in a polyepoxide matrix. The fiber pull-out test (FPO) was used to evaluate the adhesion properties by using thin films of copper for the wire fiber. For comparison, the results of the FPO for uncoated fiber with an average surface roughness of Ra = 0.03 μm were obtained. The results show an increase in toughness and strength compared with uncoated rougher fiber. The results of scanning electron microscopy (SEM) clearly show that copper debonding requires an interface fracture energy and there is a possibility of copper diffusion, which is confirmed by point EDX. The energy absorption of the wire thin film copper increased by 42%, and the maximum force pull-out increased by 14%. The modeling of the current study shows the crack initiation starts from the side of the fiber pull-out direction, and the maximum stress component was just near the free non-encompassed wire.