压力载荷作用下非圆截面管件的应力分析

采用有限元方法,分析了含椭圆度的直管、弯头在内压或内压与轴向载荷共同作用下的应力分布.考察不同载荷方式与椭圆度条件下,直管、弯头的应力分布和大小.结果表明:在两种加载方式下,含椭圆度直管的应力集中区域在长轴端部的内壁侧与短轴端部的外壁侧;仅内压作用下,弯头应力最集中的区域为弯头与直管交界处的内壁侧;当内压与轴向载荷共同...     

高压聚乙烯装置超高压反应管内腐蚀缺陷有限元分析

基于Von Mises屈服准则,采用有限元弹塑性分析方法对含腐蚀缺陷的高压聚乙烯装置超高压反应管道的应力分布进行有限元分析,研究腐蚀缺陷的长度、宽度和深度对压力管道极限载荷的影响,把分析得到的临界失效状态下的壁厚作为超高压管道爆破的安全阈值。     

环焊缝含不同心缺陷压力管道的极限载荷分析

针对环焊缝含不同心缺陷的压力管道,建立有限元模型,计算管道的极限载荷.在有限元计算结果的基础上,将极限载荷拟合为管道直径、壁厚及缺陷大小的函数.数值验算表明,拟合关系公式在管径从500 ～ 900 mm,壁厚从6～10 mm,不同心量从1°～10°范围内具有很高的精确度.     

压扁阻断下聚乙烯管道力学响应的实验研究

采用实验方法系统研究了压扁阻断工艺参数,包括压管速度、松管速度、压缩率、环境温度和管径对聚乙烯（PE）管道力学响应的影响。结果表明,压管过程中PE管道载荷随着压管速度的增大、压缩率的增大、环境温度的降低或管径的增大而增大;卸载过程中PE管道的残余变形随松管速度的增大而增大;维持阶段PE管道的载荷衰减随着压管速度的增大、压缩率的降低、管径的减小或环境温度的降低而增大。     

小管径大壁厚拔制锅炉联箱安全性测试及分析

对自行研制的小管径大壁厚单排管拔制联箱的力学特性和安全性能进行了试验研究和数值模拟计算,得到了其弹性阶段的应力分布和弹-塑性阶段的变形情况、失效模式和位置以及塑性极限载荷,并根据极限分析方法对其安全性进行了评估。     

含缺陷油气管道应力分布的数值模拟研究

含缺陷油气管道会减薄管道壁厚,从而影响管道的力学性能,当缺陷逐渐增大到一定程度时,会使管道发生泄漏事故,甚至导致火灾、爆炸等,造成重大经济损失。因此,借助ANSYS有限元分析软件,对方形缺陷、圆形缺陷、组合缺陷油气管道进行了数值模拟研究,首先考察三种缺陷的应力分布特点,其次,引入正交实验,通过改变三种缺陷的载荷和几何尺寸如长度、半径等,考察这几种因素对最大等效应力的影响规律,所得结论为含缺陷油气管道的优化设计提供一定的依据。     

含局部减薄缺陷压力管道的塑性极限载荷数值分析和安全评定研究

局部减薄是压力管道一种常见的体积型缺陷。对含体积型缺陷管道,一般采用塑性极限载荷评价其承载能力和安全性。因此准确预测含局部减薄缺陷压力管道的极限载荷,对于压力管道的安全评定具有重要意义。通过有限元分析的方法,对承受内压、弯矩及弯矩和内压组合作用下的局部减薄压力管道极限载荷开展了研究工作。研究结果表明,在内压单独作用时,局部减薄缺陷的深度和轴向长度压力管道极限载荷影响显著,而周向长度的影响较小;在弯矩单独作用时,局部减薄缺陷的深度与周向长度对压力管道极限弯矩的影响显著,而轴向长度的影响较小。根据计算结果,得到了含局部减薄缺陷管道在内压和弯矩载荷联合作用下的安全评定方法。     

基于ANSYS的隧道内输气管道应力分析

隧道内的弯管处通常是应力集中的地方,使得管道处于危险甚至失效状态。为了研究隧道内弯管在不同情况下的受力,利用有限元分析软件ANSYS建立弯管的有限元模型,明确了隧道内垂直L型和Z型弯管的应力分布情况和应力集中点。研究结果表明:在试压和运行状态下,弯头处所受的应力最大,管道内压是引起管道应力的主要因素。隧道内管道最大应力随管道半径的增大而逐渐增大,呈近似线性关系。不同形状的弯管结构分布会对弯管的应力分布产生影响。L型弯管的最大应力随两臂长的增加先增大后减小,Z型弯管的最大应力随相互平行的两弯管的增大而逐渐增大。     

不等厚性对弯头应力分布影响的有限元研究

弯头作为受压管道中的重要部件,不仅能改变管线的方向,还可以提高管路柔性,缓解管道振动和约束力,并对热膨胀起补偿作用。以往对弯头的研究只考虑壁厚均匀不变的情况,但是实际上弯头的壁厚是沿着弯曲半径变化的,并且弯头的截面也具有一定的椭圆度。通过对实际生产中弯头壁厚的调研,分别考察热推、冷弯工艺对弯头壁厚改变的影响。并应用有限元方法分析了冷弯弯头的应力状况,得出其最大应力发生点随着外拱处壁厚减薄量的增大而向外拱处转移。     

椭圆度对埋地弯管抗震性能的影响分析

为分析不同椭圆度对埋地弯管抗震性能的影响,利用软件ANSYS建立含不同椭圆度埋地弯管的有限元模型,研究不同内压荷载以及不同场地条件下椭圆弯管的地震反应,并分析应力与变形规律。研究发现:在内压与地震动联合作用下,弯管中性线处位移最大,随着椭圆度的增加,位移不断增大且最大位置由弯管截面转移到弯管与直管相交处;随着椭圆度的增加,应力最大面由外拱内表面转为内拱内表面,应加强监测与防护;含有相同椭圆度的弯管,在Ⅰ类和Ⅳ类场地上的地震反应要比在Ⅱ类和Ⅲ类场地上大;地震作用下,运行压力越小的管道产生的应力峰值越小,允许椭圆度越大。研究结果对于弯管的抗震设计与检测维护有重要的参考意义。     

Detonation velocities of the Non-Ideal Explosive Ammonium Nitrate

In order to gain a better understanding of the detonation behaviour of the non-ideal explosive ammonium nitrate, the detonation velocities of low density prilled ammonium nitrate were measured in steel tubes with different diameters and wall thicknesses. It was found that the tube diameter has a much greater effect on the detonation velocity than the confinement. The highest value observed (3.95 km/s) coincides with the ideal detonation velocity as predicted by the TIGER code in combination with the JCZ3 equation of state.     

Investigation of the temperature distribution and material limits of membrane water wall tubes of circulating fluidized bed boilers

Assuming steady state, constant bed temperature and constant tube thermal conductivity, the three‐dimensional heat conduction equations were numerically solved. It was found that the temperature distribution can be expressed as dimensionless temperature in terms of Froude number, particle to furnace diameter ratio, and local to total furnace height ratio. The models for predicting the dimensionless wall temperature distribution and dimensionless mean wall temperature were also developed in this work. Finally, the limits of common tube materials used as water wall tubes based on maximum allowable stress and oxidation criteria were also investigated.     

固定管板式换热器的温差热应力数值分析

建立由管板、壳体和换热管组成的有限元分析简化模型,利用通过CFD数值模拟得到的各个相应壁面温度数据拟合而成的温度-距离函数关系式,在ANSYS软件中对固定管板式换热器的换热管、壳体和管板表面加栽进行结构热分析,得到了温度分布模型。还将所得的节点温度作为热载荷加栽到结构时应点上计算换热器的整体温差热应力,着重分析管板与管子及壳体连接处附近的热应力分布,并给出了沿管板径向和厚度方向上的热应力变化曲线。     

固定式管束釜式重沸器管板的应力分析

利用有限元程序自动生成系统(FEPG)开发了固定式管束釜式重沸器管板的参数化有限元计算程序,并利用该程序及VAS-ANSYS接口程序对某台固定式管束釜式重沸器进行了应力分析。各工况的计算结果表明,斜锥壳对管板应力分布规律影响较大,壳程压力和温度载荷共同作用时是换热器的最危险工况,最大应力强度值的位置发生在热端管板与壳程筒体短节过渡圆弧连接处的外表面,且位于管板的最低点。     

换热器自转螺旋扭带自动阻垢技术应用研究

以内置自转塑料螺旋扭带换热器为研究对象,对换热管中有、无自转扭带时污垢的粘附速率、换热器的动态污垢热阻、管壁的磨腐速率进行了工业应用对比试验研究。研究结果表明:自转清洗扭带的防垢、除垢、清洗效果显著,扭带管的污垢平均粘附速率是普通光管的54%;动态污垢热阻比光管下降了30%;塑料扭带对管壁的磨损微乎其微。为自转螺旋塑料扭带的工业应用推广提供了依据。     

新型结构蒸发器的制造

蒸发器管程为蛇形加热管线。管束是蒸发器的核心部件 ,制造管束的关键是控制异径管以及异径管与封头管板的焊接质量。加热管线通过异径管的套管与封头管板相连接。异径管的套管与管板的连接是挠性结构 ,改善了连接点的应力状况 ;U形管的中心距和管板、支持板的中心距必须保持一致。加热管的对接焊缝必须进行 10 0 %射线探伤。由于管孔和U形弯头的中心距较小 ,异径管与封头之间的空间有限 ,为方便换热管与异径管、封头管板与异径管的焊接 ,采取从上到下 ,按排组焊、无损探伤的组装方法     

Blast Effects of High Explosive Charges Detonating in Cylindrical Steel Tubes

Described are tests of cylindrical high explosive charges with an L/D ratio of 2, centrally detonating in steel tubes of different radii and wall thicknesses to measure the bulge respectively the damaging effects of these steel tubes. The results can be described with analytical equations. For a protecting container with minimum weight the radius should be as large as possible, because the necessary tube wall thickness is quadratically decreasing and therefore the weight of the tube is linearly decreasing with increasing tube radius.     

Stress analysis at the interface of metal-to-metal adhesively bonded joints subjected to 4-point bending: Finite element method

This paper presents a study of stress states in two-dimensional models of metal-to-metal adhesively bonded joints subjected to 4-point flexural loading using the finite element (FE) method. The FE simulations were carried out on adhesive bonded joints of high support span to specimen thickness ratio undergoing extensive plastic deformations. Two different adhesive types with eight different adhesive layer thicknesses each varying between 50 μm and μm were considered. The lower interfaces in the brittle adhesive were observed to be under a lower stress state because of the constraint exerted by a relatively stiff lower adherend. The ductile adhesive layers were under a lower state of stress as a result of the lower elastic modulus. It is concluded that the degree of plastic deformation in the adhesive is dictated by the adherend stiffness and the load transfer along the interface. The effect of load and support pins is noticeable at all adhesive thicknesses. High stress localisation exists in the vicinity of the load pins. The constraint exerted by the adherends dictates the deformation gradient through thickness of the adhesive layer. Adhesive joint behaviour as determined by the adhesive properties is investigated and also experimentally validated. Conclusions were drawn by correlating the adhesive and adherend stress states.     

Measurement of static stresses on the wall of a cylindrical container for particulate solids

Measurements of the stresses acting on the base and wall of a cylindrical container were made in a 100-mm dia. steel tube containing a granular material before downward flow of the charge had commenced. The load cells used were designed for this purpose and have high sensivity and thermal stability, permitting the measurement of very small forces.

The results show that the ratio of the normal stresses on a horizontal and a vertical plane at any point in the container is substantially constant and has a value that can be predicted by a formula derived in the paper.

Drawing the Mohr circles for stress conditions in the material in contact with the wall suggests that friction at the wall is fully mobilised, the coefficient of wall friction varying slightly with depth.

The normal stress on the base does not increase as an exponential function of the bed depth and does not appear to approach a limiting value.

A small shear stress on the base of the container was detected, but friction was very far from being fully mobilised.

The results showed that deformation of the base of the container due to the weight of the charge may cause a large increase in the normal stress on the wall.     

固定管板式换热器管板与换热管的可靠性分析

主要利用ANSYS有限元软件对固定管板式换热器管板与换热管进行应力分析,获得了该结构的应力强度分布图,可知该结构的最大应力强度发生在筒体与管板的连接处,最大应力强度为160.133 MPa。然后在应力分析的基础上,利用ANSYS有限元软件中的蒙特卡罗法对该结构进行可靠性分析,经过分析获得了其在置信度为95%且初值极限状态Z〈0（Z=σs-σmax）,其中σs为材料的屈服强度,σmax为容器在使用过程中出现的最大应力）的情形下的概率平均值为3.264 8%,即说明容器的可靠度为96.735 2%,并绘制了Z在置信度为95%的情形下的分布图和输出结果参数的灵敏度图,通过此次分析证明了该固定管板式换热器管板与换热管结构是安全可靠的。