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Acoustic liner is an important component to reduce engine noise. In this work, the modal sound source characteristics of the pipeline under different flow fields were calculated and used as the input boundary for the background flow field calculation and sound propagation calculation of the Actran software, thereby establishing the sound propagation model. The influences of four structural parameters on the sound absorption effect of the muffler plate hole diameter, hole spacing, honeycomb height, and muffler plate thickness in the single-DOF acoustic liner and the double-DOF acoustic liner were studied respectively. The simulation results show that both degrees of freedom acoustic liners exhibit the phenomenon that the smaller the perforation diameter, the better the sound absorption performance within a certain range of hole diameter. The effects of hole spacing, honeycomb height, and muffler thickness on the sound absorption performance are varied with frequency, the double-DOF acoustic liner above 2500 Hz has large dissipation power and good sound absorption effect. Through the contrast verification in the flow tube test, the transmission loss of the acoustic liner of different structures under different excitation sources is compared, and a reasonable and credible simulation method is obtained.

Perylenediimide‐chitosan/γ‐poly (glutamic acid) microcapsules sizing (PDI‐CS/γ‐PGA) core–shell microcapsule is designed and used to establish a novel interphase in carbon fiber/epoxy (CF/EP) composite, and the interfacial property, as well as the damage self‐reporting of the composite, is compared with desized carbon fiber (CF‐desized)/EP and commercial carbon fiber (CF‐COM)/EP composite. The ruptured PDI‐CS/γ‐PGA microcapsule exhibits strong "turn‐on" green fluorescence from the released PDI upon mechanical stimuli. The anchoring of PDI‐CS/γ‐PGA microcapsule on carbon fiber with PDI‐CS/γ‐PGA microcapsules sizing (CF@PDI‐CS/γ‐PGA) surface results in increased chemical activity and roughness, exhibiting a weak green fluorescence signal instead of non‐fluorescence on CF‐desized and CF‐COM surface. The transverse fiber bundle tensile (TFBT) strength of CF@PDI‐CS/γ‐PGA composite is 80.97% and 31.09% higher than those of CF‐desized/EP and CF‐COM/EP composite, which is attributed to the mechanical interlocking and chemical bonding interaction between carbon fiber and epoxy matrix by introducing PDI‐CS/γ‐PGA microcapsule with spherular structure and active groups. After microdroplet testing, the strong "turn‐on" green fluorescence signal of the released PDI from the microcapsules is detected in the interfacial debonding regions, realizing the microscopic damage self‐reporting of CF@PDI‐CS/γ‐PGA composite. [ABSTRACT FROM AUTHOR]

The accumulation of ice on surface has caused great harm to lots of fields such as transportation or aerospace. Nowadays, various equipment or tools used in low‐temperature environments, which face the risk of interface icing, usually have irregular shapes. Traditional rigid anti‐icing materials are difficult to meet practical application requirements. Thus, it is crucial to develop flexible anti‐icing materials that can be applied to various shape surfaces (curved surfaces, flat surfaces). In this paper, a photoelectric synergistic flexible solid slippery surface (FSSS) is prepared by using flexible basalt fiberglass cloth, flexible copper foil, flexible polyurethane/carbon nanotubes mixture, and flexible solid lubricant (the mixture of coconut wax and coconut oil). Even under harsh conditions of the temperature as low as −80 °C, the FSSS exhibits excellent all‐day anti/de‐icing performance whether on flat or curved surface. Moreover, the FSSS shows long‐term stability both on flat and curved surface: situated in air for 60 days, submerged in water for 60 days, kept in acid environment (pH 1) and base environment (pH 13) for 30 days. Besides, the FSSS can also achieve self‐healing function under −80 °C. This flexible surface provides a novel approach for de‐icing/frosting of multi‐shaped objects in the future. [ABSTRACT FROM AUTHOR]