On quasi-static crushing of thin-walled steel structures in cold temperature: Experimental and numerical studies

The aim of the study reported herein was to investigate the effects of low temperatures on the crushing characteristics of steel plated structures. The motivation of this study is for the analysis of ship collisions in Arctic waters. A series of tensile coupon tests were performed to examine their material behaviour at low temperatures, and then quasi-static axial crushing tests were carried out on thin-walled square tubes. The test tubes were made of ASTM A500-type carbon steel, and both the tensile coupon tests of the material and the crushing tests of the tubes were performed in a liquid nitrogen cooled chamber. To reflect the conditions of the Arctic environment more realistically, the tensile coupon tests of the material were also carried out in a dry-ice cooled chamber. LS-DYNA nonlinear finite element method simulations applying a practical approach of modelling techniques were performed to investigate the structural crashworthiness of the thin-walled steel tubes numerically. The tests in the liquid nitrogen cooled chamber showed that the fracture strain of the material was not affected (reduced) by temperatures as low as −80 °C, although fracture strain was significantly reduced below −100 °C. The fracture strain results obtained in the dry-ice cooled chamber, however, show this strain to be affected (reduced) by low temperatures even between 0 °C and −80 °C, which is equivalent to the Arctic environment. It was also observed that fracture occurs in thin-walled tubes under crushing loads at low temperatures. The LS-DYNA computations also detected the fracture behaviour of test tubes in cold temperatures in a relevant way.     

压水堆核电厂蒸汽发生器传热管的降质问题

核电厂蒸汽发生器传热管的降质将影响到核电厂一回路边界的完整性。通过对蒸汽发生器传热管的降质模式进行分析，并对在役传热管无损检测技术应用以及寿命预测的介绍，从而针对产生的传热管降质的原因，采取相应的防护措施，确保蒸汽发生器传热管的安全运行。     

提高凝汽器不锈钢换热管寿命分析及采取措施

凝汽器不锈钢换热管在凝汽器上的应用越来越普及,除了以海水作为冷却介质外几乎其它冷却水全部采用不锈钢管。保证换热管长期运行是凝汽器安全运行也是汽轮机组安全运行的前提条件,从分析换热管材的特性入手,提出在凝汽器设计及安装、运行维护方面的注意事项及采取的相应措施。     

预应力混凝土管桩两种施工方法的特点比较

预应力管桩有捶击沉桩和静压沉桩两种施工方法,其各自存在优缺点及适应性,对结构设计师和土建建造师正确了解其特性和正确选用施工方法具有重要意义。     

磨料微粉粒度检测与数据处理系统设计

针对目前沉降管测定微粉粒度普遍存在数据记录和处理过程中人为因素较大,影响测试结果的准确性等问题,利用斯托克丝定律和新一代微处理器的特点,设计了磨料微粉粒度检测与数据处理系统。论文介绍了沉降法基本原理和计算数学模型、沉降液的密度和黏度与温度修正关系,给出了系统软硬件电路。通过对相关样品进行实际测量和数据处理分析,结果表明:数据记录和处理稳定、操作方便、曲线显示美观,易于扩展等特点,具有广泛的应用前景。     

矿用聚乙烯(PE)管材的性能特点

为了满足煤矿安全生产的需要,必须对矿井瓦斯进行抽放。传统抽放管路都是使用钢管,其重量大、安全性差、不易安装。矿用聚乙烯管材具有重量轻、防静电、阻燃、碰撞不起火花、耐腐蚀、耐磨损、易于安装等特点,使用寿命可达到50 a,代表着煤矿瓦斯抽放管道的发展趋势。     

2010年俄罗斯钢管工业的发展情况

2010年国际金融危机的影响逐渐减弱,在俄罗斯政府的一系列扶持政策措施的作用下,俄罗斯钢管工业得到了良性发展,出现了大幅增长.介绍了俄罗斯几大钢管生产企业--俄罗斯钢管冶金公司、俄罗斯联合冶金公司、俄罗斯车里雅宾斯克钢管公司和俄罗斯北方钢铁集团伊若尔斯克钢管厂2010年的生产经营情况.     

Integration of superconducting magnets with cryogen-free dilution refrigerator systems

There has been much recent research interest into “cryogen-free” dilution refrigerators. Cryogen-free systems have some advantages from a safety and convenience point of view as liquid cryogens are unnecessary. However, this also makes integrating the low-temperature system with a high magnetic field environment much more challenging. Here we shall describe recent successes of integrating superconducting magnets and dilution refrigerators into one system requiring a single pulse tube cooler. The resulting environment provides experimental temperatures between 7 mK and 30 K and magnetic fields up to 12 T. We shall describe the effects of AC loss heating in such systems on the pulse tube refrigerator when the field is ramped and also the effects of eddy current heating on the mixing chamber in sweeping fields.     

望亭水利枢纽更新改造工程人行桥设计与分析

望亭水利枢纽更新改造工程人行桥采用单跨70.12 m钢管桁架拱的结构形式。利用空间有限元程序建立杆单元模型,进行了动力及静力分析。通过动力分析了解了结构在人行荷载作用下的振动性能,同时通过静力分析了解了各杆件的应力情况,并对最不利杆件进行了稳定及疲劳验算,指导施工图设计。最后对施工方法作简要介绍。     

液压子站长管拖车气密试验闪燃问题原因分析及探讨

本文对液压子站长管拖车定期检验气密试验过程中管路及阀门出现闪燃现象进行了分析，并针对产生的原因提出了相应的措施。