The three-point bending responses of carbon fiber composite sandwich beams with Y-frame cores at high and low temperatures

An experimental investigation was performed to explore the effects of the temperature on the three-point bending properties and failure mechanisms of carbon fiber composite sandwich beams with Y-frame cores in this paper. The composite sandwich beams with Y-frame cores firstly were fabricated using hot-press method. Subsequently, the three-point bending experiments of composite sandwich beams were tested at eight selected temperatures which ranged from -70 degrees C to 200 degrees C. Then the effects of temperature on the bending load-displacement curves, failure mechanism and bending failure load were analyzed and discussed. The experimental results showed that the bending load-displacement curves went down as temperature increased. The fiber fracture occurred for the specimens at temperature below the glass transition temperature, while the fiber microbuckling was observed for the specimens at temperature above the glass transition temperature. In addition to the change of load-displacement curves and failure modes, the bending failure load and the value of P(T) /delta(T) decreased as temperature increased. Finally, the analytical model of bending failure load and the value of P(T) /delta(T) for the composite sandwich beam was presented. The analytical predictions were calculated and compared with experimental results.