高压容器主螺栓的有限元应力分析

文章对高压容器的重要部件一主螺栓用有限元法作了应力分析,并将完好的螺栓与螺纹局部受损后的螺栓进行比较,得出了螺栓中应力沿螺纹轴向的变化规律,为高压螺栓的设计和使用提出了改进建议。     

裂纹釉的研制及残余应力有限元分析

以长石、滑石、方解石、高岭土等为主要原料制备裂纹釉。研究了釉料配方组成对釉面裂纹效果的影响,并用有限元方法对釉层中的残余应力分布特征及残余应力对裂纹产生的作用机理进行了分析。结果表明:在1250～1300℃、保温时间30min,以及坯、釉的物理性能具有合适的差异时,可以得到效果较好的裂纹釉,且有限元对残余应力的分析与实验结果取得了较好的吻合。     

含裂纹容器的有限元分析

利用有限元通用软件ANSYS Workbench,建立容器的有限弹性体三维有限元模型,进行地震工况下不同裂纹长度、不同裂纹方向、不同支腿数量和不同容器高度下的应力分析,得到断裂力学中表征裂纹尖端附近应力场,进而得出以下结论:裂纹长轴长度和角度的变化对应力场影响;等效应力值随着裂纹长轴长度的变大显著变大,等效应力最大点随着裂纹长轴长度的变大由长轴边缘移到短轴边缘;等效应力值随着裂纹长轴角度的变大而变化,在22.5°时达到最大;等效应力最大点随着裂纹长轴角度的变大,由长轴边缘移到短轴边缘。     

螺栓联结结构的有限元优化分析

应用ANSYS参数化功能,以螺纹牙根第一主应力S1为目标函数,以螺距t和牙根半径r为设计变量,对某螺栓联结结构进行有限元优化计算,得到了最优螺栓结构,并进行了应力敏感区的讨论。     

含轴向穿透裂纹的三通管道应力强度因子有限元分析

针对开孔率d/D=0.5的焊制三通管道,基于ANSYS软件及其APDL编程,采用三维奇异元,对开孔率为d/D=0.5的焊制管道三通进行数值模拟。主要考察三通在内压、主管端部面内和面外弯矩以及扭矩载荷作用下的主管腹部轴向穿透裂纹的复合型应力强度因子。通过改变裂纹位置和尺寸,计算获得不同大小的轴向穿透裂纹由主管腹部移至焊缝附近过程中的三类应力强度因子各自的变化规律和危险位置。这些结果在应力强度因子手册中尚未涉及,对工程中含缺陷三通管道的剩余强度评定具有参考价值。     

组合裂纹漏磁检测有限元分析

用有限元法分析了组合裂纹漏磁场,得到了裂纹缺陷漏磁场空间分布,给出了裂纹深度与裂纹漏磁场磁感应强度之间的关系曲线。通过实验得到了与有限元分析结果一致的结论。     

基于ANSYS的压力容器螺栓连接有限元分析

根据GB 150.1—150.4-2011《压力容器》以及有关设计实践,可知压力容器螺栓的常规设计方法偏向于稳定性,因此造成其各部位所受拉力较高,材料损耗严重.基于此,提出基于ANSYS的压力容器螺栓连接有限元分析.以有限元分析为基础,输入材料参数,对连接结构进行参数化建模,选择单元格类型及划分网格,规定约束和边界条件...     

裂纹尖端氢扩散的有限元分析

以2．25Cr-1Mo钢为研究对象,巧妙建立计算模型,利用有限元软件分析模拟,对在应力-氢环境交互作用下该钢中裂纹尖端的氢扩散规律进行了系统研究。     

直管外表面轴向半椭圆裂纹应力强度因子KⅠ的有限元分析

利用有限元法对含外表面轴向裂纹的直管进行了分析,应用有限元软件ANSYS建立了裂纹有限元模型,采用参数化建模对内压下裂纹的应力强度因子KI进行计算,得出了影响应力强度因子的主要因素。计算表明,应力强度因子随a/t及a/c成线性变化,并与t/Do为乘幂关系。一般情况下,表面裂纹在最深点（90°）处应力强度因子最大,然后随着角度的减小应力强度因子依次减小。但是在最浅点（0°）处应力强度因子有回升趋势,且随着a/t的增加,这种回升趋势逐渐明显,当a/t=0.8时,甚至出现最浅点KI超过最深点KI的现象,这时对于结构的脆性起裂位置要慎重判断,不能单纯地以最深点KI为断裂依据。     

内外施焊接管焊接接头应力的有限元分析

应用Ansys有限元应力分析软件,根据钢制化工容器结构设计规定(HG20583-1998),分别建立了内部施焊和外部施焊的内伸入式接管与壳体间焊接接头的模型,分析了焊接接头处应力分布情况,并对焊接接头处的应力进行了对比。结果表明,内部施焊的整个焊缝X方向的应力平均值大于外部施焊焊缝;外部施焊的整个焊缝Y方向应力水平略大于内部施焊焊缝;内部施焊焊缝等效应力的应力值小,但其高应力区域范围较大。     

有限元分析中超弹材料模型采用的弹性体试验

介绍用有限元分析做超弹材料模型的弹性体试验的方法。     

轮胎与路面障碍碰撞过程显式有限元分析

将车辆简化为单自由度振动模型,采用ABAQUS有限元分析软件建立11.00R20全钢载重子午线轮胎在水平路面上滚动的三维有限元模型,模拟轮胎与路面障碍的碰撞过程,并用显式有限元程序分析轮胎在碰撞过程中的受力、变形和接地压力分布等力学特性.结果表明,碰撞过程对轮胎力学特性有很大影响.     

本构方程对橡胶材料裂纹尖端J积分有限元分析结果的影响

以电子万能试验机得到的橡胶材料的应力-应变曲线为原始数据,在Abaqus有限元分析软件中拟合了17种高弹性本构方程,对比了各本构模型的拟合结果和稳定性,分别将其作为材料模型,对含裂口的纯剪切试件裂纹尖端的J积分进行分析,并将计算结果与实验数据进行了对比。研究表明,本构模型对于裂纹尖端的J积分数值影响较大,各个模型的分析精度有所不同,故在橡胶材料的有限元分析中需要特别注意材料模型的选取。     

轮胎温度场有限元分析系统的设计与开发

研究轮胎滚动过程中的稳态热平衡状态。通过经验数据积累，从轮胎结构参数设计、断面网格划分和有限元分析、热物性参数数据库建立和温度场计算、试验数据拟合及结果输出五方面，设计轮胎温度场有限元分析系统。通过与试验数据对比，证明输出的温度场云图与稳态轮胎温度场温度分布情况一致。     

利用有限元分析方法对旁路取风骤冷器的研究

水泥窑在处置固废过程中,尤其是处置含氯元素较高的固废时,氯元素容易在回转窑系统内循环富集并致系统结皮和堵塞,旁路放风系统是解决该问题的有效手段.取风骤冷器结构是旁路放风系统的关键部件.利用有限元分析对水泥窑旁路放风系统的取风骤冷器结构(直通式结构、直切式结构、旋转套筒式结构)分别进行速度分布、温度分布和压力分布进行研究...     

Stress distribution in carbon-post applied with different composite core materials: a three-dimensional finite element analysis

The aim of this study was to investigate, using three-dimensional finite element analysis [3D-FEA], the stress and/or strain distribution of five different resin composites used in combination with carbon fibre posts. FEA models of five different light-cured composites were employed. The stress distribution of composite in combination with carbon fibre post was analysed under two different loading conditions: (i) polymerization shrinkage and (ii) load of 150 N with a 35° tilt to the long axis of the tooth. The Material Fatigue Rate [MFR%] of composite materials, dentin and fibre post was calculated. The highest stress values were recorded for Heliomolar and Clearfil-Photo P. The lowest stresses and MFR% values were attained when using Diamond Crown. High MFR% value [>45%] for carbon posts were found in all the tested cases under load. Composite materials with a Young’s modulus similar to that of dentin should be selected for the restoration of endodontically-treated teeth when using carbon fibre posts. The peak of the polymerization stress of the composite core is localized at the ferrule level. This might induce an open margin with higher risk of coronal leakage.     

Stress analysis of crazes at moving crack tips

Summary The finite element method is applied to contours of craze zones in front of moving crack tips in polymethylmethacrylate (PMMA), measured by interferometry, in order to compute the stress distribution. In contrast to the constant stress assumed in the Dugdale model, a stress distribution is found with a maximum at the crack tip then a sharp decrease and a more gradual decline over the larger part of the craze length. Computed stresses as well as the Dugdale stress increase with increasing crack speed and, hence, decreasing loading time. Generally the results obtained are in good agreement with those already found for growing crazes at stationary crack tips.     

Standard finite element techniques for efficient stress analysis of adhesive joints

The paper documents ongoing research in the field of stress analysis of adhesive bonded joints and aims at developing efficient and accurate finite element techniques for the simplified calculation of adhesive stresses. Goal of the research is to avoid the major limitations of existing methods, in particular their dependency on special elements or procedures not supported by general purpose analysis packages. Two simplified computational methods, relying on standard modelling tools and regular finite elements are explored and compared with the outcome of theoretical solutions retrieved from the literature and with the results of full, computationally intensive, finite element analyses. Both methods reproduce the adherends by means of structural elements (beams or plates) and the adhesive by a single layer of solid elements (plane-stress or bricks). The difference between the two methods resides in the thickness and in the elastic properties given to the adhesive layer. In one case, the adhesive thickness is extended up to the midplane of the adherends and its elastic modulus is proportionally increased. In the other case, the adhesive layer is maintained at its true properties and the connection to the adherends is enforced by standard kinematic constraints. The benchmark analyses start from 2D single lap joints and are then extended to 3D configurations, including a wall-bonded square bracket undergoing cantilever loading. One of the two simplified methods investigated provides accurate results with minimal computational effort for both 2D and 3D configurations.     

Three-dimensional finite element analysis of polymer rotational extrusion

A three-dimensional finite element approach has been employed to model steady, creeping, isothermal helical flows and to study the effect of an imposed rotational field in a wire coating process and a tube extrusion process. It has been shown that the rotational field can affect process characteristics with an underlying viscous character, such as the velocity profile, pressure drop, viscous extrudate swelling, material pathlines, and deformation field. Significant pressure drop reduction may be achieved with implications on the process productivity, pressure drop reduction being most prevalent at low power-law indices because of the increased nonlinearity in the shear-thinning viscosity function. Extrudate swelling has been shown to be affected by the rotational field owing to the shear-thinning nature of polymeric materials. Finally, it has been shown that significant material deformation may result from the imposition of the rotational field.