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61.
在确定了ISO-834标准火灾作用后钢材和混凝土应力应变关系的基础上,首先利用ABAQUS有限元软件建立火灾作用后方钢管钢筋混凝土短柱温度场及力学分析模型,计算结果得到以往试验结果验证。然后分析了截面边长、配筋率、受火时间、含钢率、材料强度等参数对火灾作用后钢管钢筋混凝土短柱承载力的影响规律,结果表明,受火时间、截面边长是影响其承载力的主要因素。最后提出了火灾作用后方钢管钢筋混凝土短柱承载力的理论公式, 为其灾后修复和加固提供参考。 相似文献
62.
Wu Yu-Ting Qin Zhen Eizad Amre Lyu Sung-Ki 《Journal of Mechanical Science and Technology》2021,35(7):3101-3111
Journal of Mechanical Science and Technology - Multi-rotor unmanned aerial vehicles (UAVs) are being widely used in various military and civilian fields because they can replace manned systems in... 相似文献
63.
Lee Jung Ho Jung Chang Ho Lyu Sungki Cho Jae Ung 《Journal of Mechanical Science and Technology》2021,35(1):99-105
Journal of Mechanical Science and Technology - In this study, CFRP and aluminum properties were investigated by carrying the static experiment on the shape-dependent bonding structure, and designed... 相似文献
64.
为解决传统矿井通风系统无法满足矿井扩产需求,在以老矿井为例分析其通风现状的基础上,对当前井下通风系统进行测定和评价,并针对其所存在的问题初步提出整改建议;最后,在上述分析的基础上对工作面的需风量进行重新核算,并提出三套优化方案,最终确定方案二为最佳方案. 相似文献
65.
当前配电网网架建设多以规划期末年负荷水平进行规划,忽略了负荷发展的动态过程,容易造成配电网超水平建设,导致设备利用率低、投资时效不足等问题.针对此问题,定义了负荷释放概念,提出了一种考虑负荷释放过程的配电网网架结构经济性计算模型,该模型考虑了负荷释放过程中配电网动态的运行网络损耗和停电损失,从规划期整体出发,对配电网网架结构经济性进行定量评估.运用实际地区线路进行算例仿真,仿真结果表明,该模型可以有效评估不同网架发展过程中,配电网建设的经济性. 相似文献
66.
Thermal stability,flame retardance,and mechanical properties of polyamide 66 modified by a nitrogen–phosphorous reacting flame retardant 下载免费PDF全文
Flame‐retardant polyamide 66 (PA66) was prepared by the polymerization between PA66 prepolymer and N‐benzoic acid (ethyl‐N‐benzoic acid formamide) phosphamide (NENP). Compared with the pure PA66, the flame‐retardant PA66 exhibited better thermal stability, as indicated by thermogravimetric analysis results. The limiting oxygen index was 28% and the UL‐94 test results of the flame‐retardant PA66 indicated a V‐0 rating when the content of the NENP prepolymer was 5 wt %. The flammability and flame‐retardant mechanism of PA66 were also studied with cone calorimetry and scanning electron microscopy/energy‐dispersive X‐ray spectroscopy, respectively. The mechanical properties results show that the flame‐retardant PA66 resin had favorable mechanical properties. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43538. 相似文献
67.
68.
Ni-based composite coatings containing varied contents of tungsten carbides on low carbon steel were fabricated. Effects of sintering temperature and tungsten carbides contents on the surface, interface, microstructure and wear resistance of the coatings were investigated using scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, Vickers microhardness tester, bulk hardness tester and pin-on-disc tribometer. The results indicated that with appropriate sintering temperature (1230 °C), smooth coating surfaces can be achieved. Favorable interfaces about 200 μm can be got that both the chemical composition and property of the interfacial region showed gradual transitions from the substrates to the coatings. Microstructure of the coatings consists of tungsten carbides and M7C3/M23C6 in the matrix. With excessive sintering temperature, tungsten carbides tend to dissolve. Ni-based coatings containing tungsten carbides showed much higher level of bulk hardness and wear resistance than ISO Fe360A and ASTM 1566 steels. With increasing contents of tungsten carbides from 25% to 40%, bulk hardness of Ni-based coatings gradually increased. Ni-based coating with 35% tungsten carbides performed the best wear resistance. 相似文献
69.
The dynamic mechanical relaxation behavior of Ti_(36.2)Zr_(30.3)Cu_(8.3)Fe_4Be_(21.2) bulk metallic glass with good glass-forming ability was investigated by mechanical spectroscopy. The mechanical relaxation behavior was analyzed in the framework of quasi-point defects model. The experimental results demonstrate that the atomic mobility of the metallic glass is closely associated with the correlation factor χ. The physical aging below the glass transition temperature T g shows a non-Debye relaxation behavior, which could be well described by stretched Kohlrausch exponential equation. The Kohlrausch exponent β_(aging) reflects the dynamic heterogeneities of the metallic glass. Both concentration of "defects" and atomic mobility decrease caused by the in situ successive heating during the mechanical spectroscopy experiments. 相似文献
70.
Wang Lifei Zhang Zhengyong Cao Miao Zhang Hua Han Tingzhuang Wang Hongxia Arthanari Srinivasan Cheng Weili Jinlong Lyu 《JOM Journal of the Minerals, Metals and Materials Society》2019,71(5):1705-1713
JOM - Prestretch deformation of 6.48% with various initial speeds (1 mm/min, 101 mm/min, and 100 mm/min) was carried out at 723 K to improve the formability of... 相似文献