Dynamic Tensile Properties and Failure Mechanism of Glass Fiber Reinforced Polycarbonate Composite

In order to investigate the tensile mechanical behavior and failure mechanism of polycarbonate (PC) composite reinforced by short glass fibers in different orientations at a wide range of strain rates, the tensile experiments of PC composites with 20% glass fiber content and fiber orientations of 0°, 45° and 90° were carried out at a strain rate range of 0.001－1000 s⁻¹ by using a material test machine, a medium strain rate test machine, and a split Hopkinson tensile bar device. The fractured surface morphologies of the three types of specimens under the stain rate range of 0.001－1000 s⁻¹ were analyzed with scanning electron microscopy. The experimental results showed that PC composites have significant strain rate effects on tensile propertie and failure mechanism. When the loading strain rate increases from 0.001 s⁻¹ to 1000 s⁻¹, the tensile strengths of the specimens contained 0°, 45° and 90° glass fibers are increased by 57.5%, 58.2% and 49.4%, respectively, while the failure strains are increased by 74.1%, 125.1% and 129.1%, respectively. The tensile strength of specimen with glass fiber orientation of 0° is higher than that of the other two types of specimen, while the failure strain is lower than that of the other two types of specimen. Under the strain rate of 0.001 s⁻¹ in quasi-static loading, there are four failure modes of the glass fiber reinforced PC composites: fiber pull-out, fiber fracture, matrix brittle fracture and fiber/matrix debonding. At the high strain rate of 1000 s⁻¹, there are five failure modes: fiber pull-out, fiber fracture, matrix plastic deformation, matrix plastic fracture, and fiber/matrix debonding. The adiabatic temperature rise effect under high strain rate loading leads to a softening of the PC matrix in the glass fiber reinforced PC composite, resulting in a plastic deformation and an increase of matrix/fiber interface adhesion force, which is the main mechanism of the significant increase of the failure strength and failure strain compared with that under quasi-static loading.