Xudan Yao

Electrothermal de-icing system is capable of mitigating the effect of in-flight icing on aerodynamic performance. Under the action of electric heating and aerodynamic loading, ice layer may fracture and shed before totally melted, which poses challenges for numerical modeling. In this study, a unified numerical framework for icing and de-icing is proposed, which incorporates a thermo-mechanical phase field model to characterize the de-icing behavior, with both phase transition and aerodynamic forces included. Spline interpolation method is employed to transfer aerodynamic loads across the fluid-solid interface of ice layer. After verifying the icing and de-icing modules via benchmark tests, de-icing numerical results of the iced NACA 0012 wing leading edge show that, crack initiates at the ice-airfoil interface, accompanied with the formation of water layer. The coupling of aerodynamic forces and thermal stresses ultimately yields ice fracture and shedding, which is consistent with experimental results. Besides, neglecting aerodynamics or simplifying their distribution leads to overestimation or underestimation of de-icing performance, respectively. Under uniform heating mode, a ”high-power, short-duration” de-icing strategy is found to be efficient, and the water film thickness threshold aligns with empirical criterion. De-icing time at 4° angle of attack (AOA) is longer than that at 0°AOA for uniform heating mode, while the opposite law is found for parting strip heating scheme, which can further enhance de-icing performance, especially at 4°AOA.

Fiber-reinforced composites are extensively utilized in mass-critical structures spanning aerospace, automotive, civil, etc., owing to their exceptional specific strength and stiffness. Fiber volume fraction (FVF) is a critical parameter for evaluating the performance of the composites. As a consequence, different measurement methods have been developed in recent decades, including resin removal method, thickness measurement method, microscopic method, etc. This paper reviews both traditional destructive (acid digestion, combustion, image analysis, etc.) and newly developed non-destructive techniques (X-ray CT, thermography, ultrasonic, XRD, eddy current, etc.), with a focus on their applicability to specific materials, measurement accuracy, operational complexity and cost. Moreover, key challenges and future directions are discussed, emphasizing the need for non-destructive testing, cost and energy efficiency, intelligent measurement and sustainability.