With increasing application of carbon fiber reinforced polymer (CFRP) in aerospace field, the development of new composites with both superior damping and mechanical properties has become a critical issue requiring urgent attention. Meanwhile, weather resistance of materials has also become an important factor affecting flight safety. In this study, carbon-based reinforcing media were embedded between layers of CFRP composites to investigate the effects of salt spray environments on their damping and mechanical properties, while also analyzing their corrosion resistance. The results indicated that after 60 days of salt spray aging, the damping performance of CFRP laminates with embedded carbon-based media increased by 9.12 %. Although the flexural properties and Mode II interlaminar fracture toughness decreased, they were still higher than those of laminates without embedded media. Additionally, carbon-based media could effectively impede the diffusion and permeation of water molecules in the interlayer region. Scanning electron microscopy (SEM) and ultrasonic Cscan were used to observe the internal aging damage of composites, and the enhancement mechanism of carbonbased reinforcing media on CFRP composites was revealed. These findings provide new insights for developing high-performance CFRP composites and offer valuable reference for enhancing the structural reliability and service life of marine flight equipment.

Unidirectional Glass Fiber Reinforced Plastic (GFRP) laminates were prepared by inserting three-dimen-sional (3D) CNTs/carbon black film or CNTs/graphene oxide (GO) film into the laminates to improve the interlaminar performance. The effects of low-temperature cycles (35 cycles between -58 degrees C and room temperature (RT)) on the samples were investigated, and the damage caused to the reinforcement layer was directly detected by comparing the interlaminar images. By comparing the experimental results of the double cantilever beam (DCB) and end notch bending (ENF) test, the optimising effect of the new composite film (CNTs/carbon black film) on the interlaminar fracture toughness was verified. The results showed that the interlaminar fracture toughness of CNTs/GO film and CNTs/carbon black film in modes I (ENF test) and II (DCB test) was similar and superior to that of CNTs film. Regarding the effect of the low-temperature cycles on the samples, the change of CNTs/carbon black film and CNTs/GO film is also lower than that of CNTs film. Finally, the matrix interface and failure mechanisms of the interlaminar reinforcement were investigated by scanning electron microscope (SEM). (c) 2023 Elsevier B.V. All rights reserved.

战时飞机蒙皮受到子弹攻击会产生损伤,影响直升机的正常飞行,采用传统工艺修复所需时间较长.针对这一问题,对一种基于胶接剂和纤维预浸料的蒙皮快速抢修的新工艺方法进行了研究.首先,对此工艺的修补方案及流程进行了介绍;其次,在上述研究的基础上,采用仿真与试验结合的方法研究了修补方式和打磨方式对修补后蒙皮强度的影响;最后,采用试验对上述研究结果进行验证,得出采用此工艺方法修复后的蒙皮,其强度可达到蒙皮母板强度的98％以上,其修复时间缩短为传统复材修复工艺的2/3,其修复重量为传统工艺的1/3.

Currently, hole making processes in carbon fiber reinforced polymers (CFRP) generate powdered chips that cannot be automatically recovered in real time. The present work attempts to solve this problem using a new drilling-chip removal system called the suction-type internal chip removal system. It can discharge the powdery chips generated in the CFRP hole making process in a timely and effective manner during the drilling process. Based on the requirements of the drill bit used in this system, the following studies are carried out in this work: (1) Using statistical methods, the chips produced in CFRP hole making were classified, the chip distribution was analyzed, and the study of the influencing factors of chip size were completed; (2) based on these studies and the gas–solid two-phase fluid mechanics, a FLUENT simulation is used to define the center distance and center angle of the inner runner for the design of the drill bit. The influence of the center distance of the inner runner, the center angle of the inner runner, and the cross-sectional shape of the inner runner on the chip removal effect of the inner runner of the tool is given. Finally, by fabricating the chip removal system and drill, the correctness of the internal flow channel structure design of the internal chip removal drill was verified.

In this research, polydimethylsiloxane (PDMS) and graphene nano-platelets (GNPs) were used as flexible substrates and conductive layers. A facile and template transfer method combined with a low-cost solution-spraying process was adopted to prepare the microdome array GNPs/PDMS flexible strain sensor. The microdome array produces different degrees of in-plane deformation and the gradient distribution of the GNP conductive network on the surface during stretching. This affects the contact effect between the adjacent cells of the GNP conductive network on the film surface in different strain ranges, thereby realizing a sensitive resistance response. The strain sensor of the microdome array GNPs/PDMS exhibits excellent gauge factors (GF) of 8.98 (0.26% < epsilon < 20%), 18.31 (20% < epsilon < 43%), and 34.57 (43% < epsilon < 60%), the highest of which is 8 times higher than that of the planar GNPs/PDMS strain sensor without a microdome array. In addition, the material exhibits remarkable stability and durability (10 000 cycles), fast response time (125 ms), and stable relative frequency/ strain sensing performance. Finally, the strain sensors of the microdome array GNPs/ PDMS were packaged for various application tests, showing broad application prospects in electronic skin, wearable electronic devices, and component health monitoring.

Drilling force is the main factor affecting the quality of carbon fiber-reinforced polymer (CFRP) holes and tool wear. Choosing appropriate process parameters can effectively control the drilling force and improve the quality of hole making and tool life. This study aimed to accurately predict and effectively control the drilling force during the chip removal hole drilling process in CFRP. First, a CFRP internal chip removal machining drilling force prediction model was derived based on the support vector regression (SVR) theory, and a suitable kernel function and loss function were introduced into the model to improve the prediction accuracy of the model. Second, a drilling experiment of the given type of CFRP material with internal chip removal was designed, and sequential minimal optimization was applied to solve the unknown parameters in the prediction model. The drilling force and tool parameters, suction parameters, and cutting parameter prediction models were constructed for processing a given type of CFRP material. Finally, using the constructed prediction model, the relationship between cutting parameters (speed and feed), tool parameters (drill diameter, peak angle, and relief angle), and suction parameters (negative pressure) and axial force during CFRP internal chip removal hole drilling was predicted and studied. The relationship between the aforementioned parameters and the axial force was in line with the research results of existing studies, and the selection range of tool parameters, cutting parameters, and suction parameters when processing a given CFRP material using an internal chip removal process was also given.

本文主要围绕碳纤维复合材料(CFRP)与2024Al的连接件,研究低温环境下螺栓连接的拉-拉疲劳问题.首先进行不同环境下的拉伸实验,从中获得最大静力载荷,并通过静载破坏曲线探究不同温度下异质材料连接层合板接头的损伤过程,通过观察不同温度下的拉伸破坏现象,对比复合材料层合板纤维分层与撕裂程度,以此为依据研究低温环境对异质材料螺栓连接疲劳的影响,选用不同温度分组的层合板接头分别在各自85％、80％、75％的最大静载条件下进行常温与低温疲劳实验,实验结果拟合常温与低温下的S-N曲线.结果表明,在其他实验条件相同时,低温环境下层合板接头拉伸破坏强度相比于常温环境增强.分析疲劳曲线得出低温环境下层合板接头受疲劳载荷能力更强.

目前,无人机及其相关企业正处于发展阶段,分析好沈阳市无人机及其相关企业的现状,可以为沈阳市无人机企业的发展与壮大起到助推作用.文章利用数据统计、数值分析等方法,对当前发展沈阳市无人机相关政策、沈阳市无人机产业市场、专利水平等因素进行了综合分析,阐述了沈阳市无人机及其相关企业的现状,并针对现状中存在的问题,提出了助推沈阳市无人机发展的建议,以期为政府和相关企业提供参考思路.

为了预测不同压强下柴油的密度并观察不同压强下柴油密度的变化趋势,首先建立了压强和柴油密度之间的微分方程模型;随后,利用Python语言编写了四阶Runge-Kutta方法的迭代条件以求解微分方程.结果表明:预测的结果基本符合实际,柴油的密度随压强的变化幅度较大.

在无人机企业渐渐兴起的今天,无人机模块化一直处于无人机及其相关产业的新兴领域,而作为支撑无人机飞行的动力装置,因其设计难度大,维修拆卸不方便,制作成本大等困难,跻身成为了无人机产业发展的制约因素.为此,许多科研团队提出了将无人机动力装置模块化的设想,以期找寻无人机研发的新思路.本文就无人机模块化自身特征,对无人机动力装置模块化的优势进行了分析,并对其发展中存在的问题提供了参考性的解决方案.

This paper introduces a safe self-centering Tapping and Threading Device, which combines the functions of the hinge bar and the die holder to achieve the purpose of convenient and efficient thread processing, reducing the labor intensity of workers and ensuring product quality. Improve production efficiency, reduce production costs, and improve economic efficiency.