Coupling effect of temperature and off-axis angle on the compressive properties of needled carbon/quartz fiber-reinforced phenolic resin composite

Abstract

Studying high temperature off-axis compression of composites is key for advancing aerospace, optimizing designs, and developing innovative materials. For this objective, the impact of temperature and off-axis angle (denoted as θ) on the compressive properties of needled carbon/quartz fiber-reinforced phenolic resin (CF-QF/PF) composite has been explored. Initially, the thermal behavior of the materials was assessed through thermogravimetric (TG) analysis, followed by 25 sets of static compression tests across five off-axis angles at five temperatures. Subsequently, a model was applied to predict the strength and modulus under high temperature off-axis compression, with an average error of less than 1 %. The coupling failure mechanisms were then analyzed through various microscopic observations. The findings indicate that when T = 400 °C, temperature exposure reduces modulus and strength to 0.43 and 0.32 of their normalized values, respectively. Such findings suggest temperature has a more significant impact on strength. Meanwhile, TG results provide evidence for the significant property loss when T = 400 °C. A specific combination of temperature and off-axis angles will lead to a more pronounced reduction in strength and an increase in failure strain, while such an effect on modulus is less significant. Post-mortem analysis reveals that temperature contributes to matrix softening and weakening of the fiber-matrix interface. Compared to specimens with θ = 90°, others exhibit more frequent fiber bundle cracks and microcrack propagation along the fiber-matrix interface, adversely affecting their high temperature performance.