Experimental study on dynamic properties of BFRP laminates used for structural strengthening under high strain rates

Fiber reinforced polymer (FRP) has been widely used for structural strengthening due to its outstanding mechanical properties and excellent chemical resistance. Basalt fiber is a new type of fiber which has greater failure strain than the commonly used carbon fiber and higher tensile strength than the E-glass fiber. At the same time, it shows good resistance to chemical attack, impact load and fire with less poisonous fume. Therefore, application of basalt fiber reinforced polymer (BFRP) as a strengthening material to retrofit structural components against seismic and blast loads is very promising. Currently the quasi-static properties of BFRP composites have been extensively studied, however, researches on their dynamic properties are rather limited. In this study, mechanical properties of unidirectional BFRP composites under the strain rate ranging from 0.00006 s(-1) to 260 s(-1) are derived from quasi-static and dynamic tensile tests. A universal testing machine was used to conduct the quasi-static and low-speed tensile tests and a high-speed servo-hydraulic testing machine (INSTRON VHS 160/100-20) was applied to conduct the high-speed tests, respectively. Test results showed that the mechanical properties of BFRP are strain rate dependent. Strain rate effects on tensile strength, Young's modulus, and failure strain are analyzed and discussed. Based on the testing data of present study and data collected from other literatures, empirical equations of dynamic increase factors (DIFs) in terms of strain rate are derived to estimate the dynamic mechanical properties of BFRP within the strain rate range considered. (C) 2020 Published by Elsevier Ltd.