Simulation of hydrogen diffusion in welded joint of X80 pipeline steel

Hydrogen diffusion coefficients of different regions in the welded joint of X80 pipeline steel were measured using the electro-chemical permeation technique. Using ABAQUS software, hydrogen diffusion in X80 pipeline steel welded joint was studied in consideration of the inhomogeneity of the welding zone, and temperature-dependent thermo-physical and mechanical properties of the metals. A three dimensional finite element model was developed and a coupled thermo-mechanical-diffusion analysis was performed. Hydrogen concentration distribution across the welded joint was obtained. It is found that the postweld residual hydrogen exhibits a non-uniform distribution across the welded joint. A maximum equivalent stress occurs in the immediate vicinity of the weld metal. The heat affected zone has the highest hydrogen concentration level, followed by the weld zone and the base metal.Simulation results are well consistent with theoretical analysis.     

X80管线钢焊接接头氢分布的数值模拟

利用ABAQUS有限元软件,建立了三维有限元模型,对X80管线钢焊接接头的氢扩散行为进行了模拟. 通过对不同焊接条件下温度场、应力场、氢扩散的三场耦合模拟,研究了焊接工艺参数对焊接接头中氢扩散及分布的影响. 结果表明,焊接热影响区残余应力水平最高,是整个接头的应力集中部位,也是焊接接头中的富氢地带. 适当地提高预热温度和焊接热输入,均有利于焊接接头中氢的扩散逸出,降低氢在焊接热影响区的聚集程度,从而降低氢致裂纹的敏感性.     

饮料中人工合成食用色素的分析质量控制

浙江省１４个地、市、县防疫站在实验室培训和统一检验方法的基础上，开展了饮料中人工合成食用色素的分析质量控制工作。评分原则以室内为主，室间为辅。分别从基本数据、标准曲线、色谱图、分析系数、标样测定结果等方面具体评分。结果总分９１．５～９７．７５分有７个，８０．２５～８７．２５分有５个，６１．５～６９分有２个。     

基于PC平台的小型核动力装置仿真系统

本文介绍了一个小型核动力装置仿真系统的基本组成及基本功能,并对仿真的范围、使用的数学模型、计算方法进行了描述。本系统具有硬件投入少、组织简便及操作灵活等优点。     

应用综合法吊装钢屋架钢中环

中介绍用三角龙门架配合卷扬机吊装中环,用对称方法,加钢筋柄担方法．吊装钢屋架,用角钢托架的4点吊装法吊装3mm钢板。     

数学归纳法的原理及推广

用集合论的观点对古典的数学归纳法给出严格的证明，并对数学归纳法的基本形式加以推广，从而使数学归纳法有了理论根据，扩大了其应用范围。     

职校生成就动机分析与培养

分析了职校生这一特殊群体的特点及职校生成就动机的特征。认为教师有责任引导学生形成适当的成就动机。要通过帮助学生树立适当的成才目标、获得学习的成功体验，教会学生进行积极归因等途径，加强对职校生成就动机的培养，以促进其成才。