The effect of nanozirconia, nanotitania, and fumed silica on the mechanical, thermal, and ablation behaviour of carbon-phenolic (C-Ph) composites is investigated. The inorganic nanofillers at different loading percentage are used to prepare nano-C-Ph panels by the compression moulding technique. The dispersion of nanofillers is confirmed through SEM analysis. After manufacturing of C-Ph laminates, the mechanical properties such as tensile strength and hardness are evaluated and the effect of these fillers is investigated. Thermal conductivity, thermal erosion, and back wall temperatures were measured to understand the thermal and ablation behaviour of nano-C-Ph laminates. Additionally, the ablation mechanism is analysed by performing SEM analysis of partially and fully burnt composite laminates. The erosion resistance and burnout time of zirconia-C-Ph panels significantly improved with increase in filler loading percentage; however, the back wall temperature rises with filler loading. Titania-filled C-Ph panels show a better control over the back wall temperature but with a poor erosion control. Silica-filled composite panels have shown a balance between decreased back wall temperature with a reasonable erosion rate and burnout time.

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Fiber-reinforced polymer (FRP) composites are exposed to various corrosive media during their service life, which adversely affects their material properties. Here, a novel approach is developed to investigate the long-term performance of glass FRP composite laminate immersed in produced water generated in oil fields. This is achieved by monitoring the internal hygroscopic strain developed over the aging time using embedded fiber Bragg grating sensor. Composite material strength reduction over the immersion time is evaluated by conducting destructive mechanical tests at regular intervals, and the mechanism of property degradation is established. It is observed that property degradation follows first-order kinetics and absorption of produced water medium obeys dual-sorption diffusion kinetics. Moreover, the strain developed within the composite laminate is formulated by considering the unified influence of swelling and chemical degradation. The predicted strain closely interprets the experimentally recorded strain. This work proves that the strain measurement is an effective nondestructive technique to estimate the property of FRP composite laminates on a real-time basis.

A novel approach is developed to evaluate the property retention on prolonged ultra-violet exposure and hence, health monitoring of glass fiber reinforced polymer composite laminate. This is achieved in a non-destructive manner by mapping the strength retention with the established strain. Embedded fiber Bragg grating sensor and strain gauges are employed to monitor the strain evolution within the laminate. Tensile and flexural tests are conducted at regular intervals to estimate the mechanical strength retention with varying duration of ultra-violet exposure. Through this analysis, it is observed that the property degradation mechanism follows the first-order reaction kinetics. The degradation of matrix material along with the stress relaxation over time develops the stress–strain fields near the interfaces of matrix and fiber. Moreover, the established strain is interpreted by formulating the model that considers the unifying influence of stress relaxation and chemical degradation. This model has closely (R2 = 0.9810 and 0.9790) predicted the experimental data of strain than the existing ones (R2 = 0.9142 and 0.9119). Besides, property retention is mapped with the predicted strain. More importantly, FESEM and FTIR confirm the fact that ultra-violet radiation degrades the matrix material, and thus the mechanical property gets significantly deteriorated. This suggests that the strain measurement is an effective, non-destructive and health monitoring technique to assess the property degradation of the manufactured glass fiber reinforced polymer composites.

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