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In order to characterize in-plane shear behavior of 2D-C/SiC composites，a macroscopic cross-ply laminate model and a microscopic mini-composite model were proposed，considering damage mechanisms such as matrix cracking，interface debonding，and fiber bridging and bending. By introducing the influence of thermal misfit stress and characterizing both the unloading elastic strain and residual strain，a temperature-dependent in-plane shear constitutive model for the material was established. In-plane shear tests with 2D-C/SiC composites were performed at room temperature to validate the model. It is found that the residual strain and elastic strain increase while the unloading modulus decreases gradually with increasing shear stress. The model was then used to simulate the shear behavior. The results show that the predictions of elastic strain，residual strain，unloading modulus， and apparent stress-strain relationship are all consistent with the tested data，which preliminarily illustrates the reasonability and accuracy of the analytical model. On this basis，the in-plane shear stress-strain curves of 2D-C/SiC composites at different temperatures are presented，providing a reference for thermal structure design.

In order to better realize the intelligent perception of fault location information of power distribution communication access networks in different scenarios, this paper carries out the construction of a power distribution communication network system through industrial Ethernet technology combined with EPON technology under fiber optic communication technology. Based on GIS technology and combined with OTDR technology, we constructed a fault location system for the fiber optic cable of the power distribution communication network so as to realize the acquisition of fault location information. From the multi-source state information, the joint Kalman filtering model is used to excavate the characteristics of the grid operation state, and then the fusion of multi-source heterogeneous data of power distribution communication is realized. To verify the effectiveness of the distribution communication network system constructed in this paper for locating fault information and intelligently collecting power consumption, system tests were conducted. The results show that the relative error of the node voltage estimation of the joint Kalman filter algorithm is below 0.015%, which improves the accuracy of fault identification in the distribution network. The system constructed in this paper for information transmission connectivity testing PON port light-emitting power range of 2~6dm, receiving optical power greater than -25dm, each PON port without power overload. This shows that the distribution automation communication network constructed in this paper meets the information collection requirements, and the construction of an intelligent distribution communication network can meet the requirements of distribution automation and can also accurately collect the fault location information of the distribution network.

In order to characterize the Ⅰ-Ⅱ mixed-mode fracture performance of 2D-C/SiC composites, Arcan butterfly specimens with unilateral cracks were used, and the mode-Ⅰ and mode-Ⅱ fracture shape factors of the specimen were calibrated through finite element model. The Arcan disc device was used to carry out mode-Ⅰ, mode-Ⅱ and Ⅰ-Ⅱ mixed-mode fracture tests upon 2D-C/SiC butterfly specimens, and the macroscopic and microscopic fracture modes and strength properties of the specimens under different loading paths were investigated. The results show that the fracture toughness of mode-II of 2D-C/SiC material is higher than that of mode-I. With increasing of the loading angle, the influence of shear stress on the crack propagation path increases, and meanwhile the fracture resistance of the specimens presents a tendency to increase. The applicability of several fracture criteria is demonstrated, and an Ⅰ-Ⅱ mixed-mode fracture criterion for 2D-C/SiC composites is suggested.

Understanding the plastic behavior of crack tips is crucial for improving the fracture toughness of nanometals. Although many studies are carried out, most previous studies focus on pure metals, and how the crack tip accommodates the plastic deformation of highly concentrated solid‐solution alloys is unclear owing to a lack of direct atomic‐scale evidence. In this study, the atomic‐scale plastic behavior of the crack tip in face‐centered cubic (FCC) AuCu alloy nanocrystals is observed in situ, which provides direct evidence that plastic deformation is governed by the generation of deformation twins and hexagonal close‐packed (HCP) 2H and 4H phases, recurrence of reversible FCC‐HCP phase transitions, and detwinning, which are rarely observed in pure metals. This unusual behavior originates from the inherent chemical inhomogeneity of the AuCu alloy, which inhibits twin thickening via partial dislocations on the adjacent plane, instead of random generation of deformation twins, phase transitions, and reversible processes. This naturally implies a similar behavior at the crack tip in other highly concentrated solid‐solution alloys, including high‐medium‐entropy alloys, providing important insights that greatly improve the understanding of the fracture toughness of metallic materials. [ABSTRACT FROM AUTHOR]

The three‐dimensional (3D) vortex gliding arc plasmatron (GAP) is a promising gliding arc source due to its high reactant conversion rate and high energy efficiency, but there are few studies of its discharge characteristics. In this work, a 3D GAP device with a quartz window on the inner electrode is designed and studied. By means of high‐speed photography, high‐resolution current/voltage signal acquisition, and emission spectra, the effects of arc current, gas flow rate, electrode diameter, and electrode polarity on the discharge characteristics of this GAP are investigated. Results show that the volt‐ampere characteristic of GAP can be accurately predicted by similarity theory, and that the voltage for reverse‐polarity is significantly greater than that for normal‐polarity. Arc dynamics show that the arc at the inner electrode has the feature of high‐speed rotation, while the arc at the outer electrode has an extended current channel along with a large‐scale re‐strike process. The rotation speed and current channel length are closely related to electrode polarity, which can be ascribed to the movability of the cathode arc root. Emission spectra confirm that the plasma produced by GAP has typical non‐equilibrium properties, in which the rotational temperature ranges from 2,400 to 3,000 K and the vibrational temperature from 4,700 to 6,000 K. Moreover, abundant active free radicals, including NO, N2+$$ {\mathrm{N}}_2^{+} $$, O, and N, are detected in the plasma region. This investigation provides a better understanding of the discharge characteristics of 3D GAP, and will help to guide its further design and application. [ABSTRACT FROM AUTHOR]