峰值应力基本特性分析和讨论

对峰值应力是否仅是沿壁厚非线性分布的分量，是否都具有自限性进行分析、讨论。     

压力容器分析设计中应力线性化原理及其计算

扼要介绍压力容器分析设计中应力线性化的基本原理,并详细阐述了非轴对称模型和轴对称模型下应力线性化的基本计算方法。目的在于为压力容器的分析设计提供参考,以准确地分析器壁的应力情况。     

压力容器圆柱型筒体上接管的局部应力分析

使用有限元分析软件,对压力容器的接管部位进行局部应力分析,得到了接管处应力强度的分布情况,并在危险截面处进行应力线性化处理,得到薄膜应力、薄膜应力+弯曲应力等各项指标。通过JB4732-1995《钢制压力容器——分析设计标准》进行应力评定,设备结构满足设计要求。     

ANSYS在应力分析设计中的应用

分析设计是工程与力学结合的产物 ,也是压力容器设计方法和手段的更新。本文介绍了 ANSYS软件中的应力线性化原理和热—结构耦合计算在压力容器分析设计中的应用 ,阐述了其分析应用过程 ,并完成了一个立式贮罐的应力分析设计     

全焊接板式换热器应力分析及评定

利用ANSYS软件建立了全焊接板式换热器管侧集合箱的有限元模型,通过有限元分析得到模型的应力大小和分布。并对管侧集合箱进行了应力等效线性化处理,分解得出均布薄膜应力和线性弯曲应力,继而根据有关标准对应力校核线所在的部位进行了应力分类,并给出了应力强度评定结果,为全焊接板式换热器的设计与制造提供参考。     

超长钢筋混凝土水池无缝结构设计方法

分析现浇超长钢筋混凝土水池温度缝设置存在问题,提出不设置温度缝的设计方法,施工阶段采用补偿收缩混凝土解决水化热等效温差、干缩等效温差应力的措施,确保混凝土在浇筑和凝固过程中不出现拉应力,实现浇筑时不出现干缩裂缝;长期使用阶段采用预应力筋产生的预应力,抵抗因季节负温差产生的温度拉应力,避免出现结构裂缝。     

用应力分析设计方法设计化工压力容器与常规设计方法比较

针对化工压力容器的应力分析设计,从原理、方法及步骤进行了介绍,阐述了应力分析设计的特点和与常规设计的不同之处在于设计思想,分析设计放弃了传统的“弹性失效”准则,而采用以极限载荷、安定载荷和疲劳寿命为界限的“塑性失效”与“弹塑性失效”准则,允许结构出可控制的局部塑性区,允许对峰值应力部位作有限寿命设计。提出分析设计对新工艺、新材料、新结构和新工况的设备更具有科学性和可靠性。     

对分析设计中峰值应力与应力集中关系的理解

对薄壳开孔和开孔接管产生的应力集中的性质及与峰值应力的关系进行了深入的讨论,明确提出了薄膜应务集中,二次应力集中和表面应力集中的概念,论述了峰值应力的条件和应力处理线适当选取的重要性。     

废热锅炉薄管板的三维机械应力分析

运用有限元分析软件ANSYS,对废热锅炉建立了考虑筒体和换热管影响的管板真正实际结构的三维模型,对其进行机械应力分析,得出管板的变形和应力分布云图.将分析结果进行应力线性化处理,按照JB4732-95<钢制压力容器--分析设计标准>中的应力分类和评定方法对管板进行了评定.     

化工管道设计中的管道应力分析

化工管道作为当下我国化工企业可持续发展不可或缺的重要基础设施，其设计的合理性直接决定管道运行过程的安全性。管道应力分析作为化工管道设计环节的重要部分，与管道安全紧密关联。由于主客观因素限制，现阶段部分化工管道设计施工还存在一定不足，不利于化工行业长远发展。鉴于此，本文基于化工管道应力的概念分析，分别探讨化工管道一次应力、二次应力和峰值应力，结合化工管道设计中应力分析目的及具体分析内容，分别从柔性管道设计方式的引入、管网柔韧水平的提升和冷紧措施的引入三个方面提出化工管道设计中应力水平有效削减的具体策略，仅供设计人员进行借鉴与参考。     

Analysis and design of adhesive-bonded tee joints

In this study, the stresses in adhesive-bonded tee joints, in which a right-angled plate is bonded to a rigid plate with an adhesive, have been analysed with a finite element method. It was assumed that the adhesive and adherends had linear elastic properties. The tee joint was analysed under three loading conditions, two linear and one bending moment. The stress distributions in the joint area are given by stress contours and XY plots under the three load conditions. It was found from the results that high stress concentrations occur in the inside corner of the angle plate for loading in the x-direction (P_x) and under bending moment (M), this suggesting that failure would not occur in the bonded joint. However, for loading in the y-direction (P_y), the maximum normal stresses are concentrated at the left free end of the adhesive layer in the joint, and the first failure may be expected at this edge. Since the geometry of the joints affects the analysis and design of such joints, the influences on the stress distributions of the overlap length, adhesive thickness and adherend thickness were investigated. Practical experiments were carried out and it was found that experimental results were in good agreement with those of the finite element analysis.     

直接法在加氢裂化反应器分析设计中的应用

压力容器分析设计一般采用基于弹性应力分析与塑性设计准则的应力分类方法,应力分类法在工程应用中有时存在应力分类困难以及部分结构的设计结果偏于不安全等问题。针对某加氢裂化反应器上封头开孔接管结构,采用欧盟压力容器标准EN13445提出的基于失效模式和弹-塑性分析的分析设计方法——直接法加以分析,结果表明,直接法用于压力容器分析设计简便可靠,值得推广。     

Determination of thermal stress distribution in a model microelectronic device encapsulated with alumina filled epoxy resin using fluorescence spectroscopy

A method for measuring residual and applied stresses in particulate polymer systems, which utilizes the piezo-spectroscopic effect of the optical fluorescence of filled particles, is presented. Fluorescence piezo-spectroscopy (PS) is non-destructive and provides microscopic lateral resolution upon using an optical microprobe system. Epoxy resin filled with α-alumina particles is used in this study. Stress values are obtained by frequency shift measurement of the characteristic optical fluorescence lines produced by Cr³⁺ impurities in alumina. The relationships between peak frequency shift of these lines and stress are derived by using a 4-point-bending test. The peak frequency shift shows linear correlation with tensile stress, while a non-linear relation between peak frequency shift and stresses is found in the compressive stress region. To a first order approximation, residual stresses were calculated by the frequency shift divided by the linear correlation coefficient in the tensile stress region. As an application of the PS method, we determined micron order residual stress distributions in a model plastic encapsulated silicon substrate for microelectronic devices and compared the stress data with those calculated using a two-dimensional finite element analysis of the device. The experimental results were in good agreement with the tensile stress components that have been obtained by theoretical calculation. Therefore, PS techniques can be used to measure residual stresses in polymer compounds utilizing the information obtained from the fluorescence lines of a dispersed ceramic powder.     

液化天然气储罐顶部进液管的有限元分析

低温管道系统结构复杂,在工作时承受内压、温差及重力载荷,且承载时系统内各部件又相互影响和制约,采用传统材料力学或结构力学很难分析该系统内各部件应力情况。应用ANSYS软件对某液化天然气储罐的顶部进液管进行了结构强度分析,分析得到了顶部进液管在承受内压、自身重力以及温差应力作用下的变形和应力分布情况,基于此对进液管的布置进行结构调整。研究结果表明:优化设计后进液管道最大主应力小于原设计进液管最大主应力的1/6,极大地保证了储罐在使用过程中的安全性。     

Geometrically non-linear analysis of adhesively bonded corner joints

When adhesively bonded joints are subjected to large displacements, the small strain-small displacement (linear elasticity) theory may not predict the adhesive or adherend stresses and deformations accurately. In this study, a geometricaly non-linear analysis of three adhesively bonded corner joints was carried out using the incremental finite element method based on the small strain-large displacement (SSLD) theory. The first one, a corner joint with a single support, consisted of a vertical plate and a horizontal plate whose left end was bent at right angles and bonded to the vertical plate. The second corner joint, with a double support, had two plates whose ends were bent at right angles and bonded to each other. The final corner joint, with a single support plus angled reinforcement, was a modification of the first corner joint. The analysis method assumes that the joint members, such as the support, plates, and adhesive layers, have linear elastic properties. Since the adhesive accumulations (spew fillets) around the adhesive free ends have a considerable effect on the peak adhesive stresses, they were taken into account. The joints were analyzed for two different loading conditions: one loading normal to the horizontal plate plane P_y and the other horizontal loading at the horizontal plate free edge P_x. In addition, three corner joints were analyzed using the finite clement method based on the small strain-small displacement (SSSD) theory. In predicting the effect of the large displacements on the stress and deformation states of the joint members, the capabilities of both analyses were compared. Both analyses showed that the adhesive free ends and the outer fibres of the horizontal and vertical plates were subjected to stress concentrations. The peak stresses appeared at the slot corners inside the adhesive fillets and at the horizontal and vertical plate outer fibres corresponding to the locations where the horizontal and vertical adhesive fillets finished. The SSLD analysis predicted that the displacement components and the peak adhesive and plate stress components would show a non-linear variation for the loading condition P_x, whereas the SSSD analysis showed smaller stress variations proportional to the applied load. However, both the SSLD and the SSSD analyses predicted similar displacement and stress variations for the loading condition P_y. Therefore, the stress and deformation states of the joint members are dependent on the loading conditions, and in the case of large displacements, the SSSD analysis can be misleading in predicting the stresses and deformations. The SSLD analysis also showed that the vertical and horizontal support lengths and the angled reinforcement length played an important role in reducing the peak adhesive and plate stresses.     

Elastic analysis and engineering design formulae for bonded joints

The general elastic plane strain problem of adhesively bonded structures which consist of two different adherends is considered. To facilitate a truly general approach the adhesive joint is modelled as an adherend-adhesive sandwich with any combination of tensile, shear and moment loading being applied at the ends of both adherends. A full elastic analysis is presented which calculates the adhesive shear and tensile stresses in the overlap region, this analysis has been validated for a range of load cases using a finite element program. Basic design approaches are outlined and explicit expressions are developed which enable the simple evaluation of the stress distributions in the adhesive overlap. Simplified two parameter design formulae are also produced which accurately describe the peak stresses at the ends of the adhesive overlap in both the transverse and longitudinal shear directions. In all of the analyses the adherends are assumed to behave as linear elastic cylindrically bent plates with the adhesive forming an elastic interlayer between them. In the simplified analyses only one component of adhesive stress is considered, while in the full elastic analysis two components of stress are considered with a consequent increase in the complexity of the required solution method, but also an increase in accuracy over the simplified analyses for a wider range of joint configurations.     

关键管系的应力分析

采用ＦＡＯＰ应力分析软件，对氨合成塔出口至废热锅炉进口管系的设计进行应力分析     

注射过程中残余应力演变的模拟与分析

采用线性黏弹性模型，模拟计算了平板形状制品残余应力在壁厚方向和流动方向上的分布及其在成型中的变化过程。根据模拟结果，深入讨论了注射成型过程中残余应力的形成机理和演变情况。结果表明：脱模时制品表层有着较大的拉应力，表层以下存在着一个应力低谷，在制品中心区域存在着抛物线形的拉应力分布；残余应力沿壁厚分布的形状在流动方向上基本相同，但是流动末端的应力值稍大于流动入口处。     

1500m3球壳板曲率超标球罐有限元应力分析与强度校核

对1500m3曲率超标球罐在水压试验和设计压力工况下进行了有限元应力分析计算,并根据应力分析设计方法进行了强度校核。结果表明应力强度合格,但最大应力点偏移到超标曲率最大点处。参考应力分析计算结果,提出了球壳板曲率超标球罐的处理措施。     

Analysis and design of adhesively bonded tee joints with a single support plus angled reinforcement

In this study, stress and stiffness analyses of adhesively bonded tee joints with a single support plus angled reinforcement were carried out using the finite element method. It was assumed that the adhesive had linear elastic properties. In actual bonded joints, some amount of adhesive, called the spew fillet, accumulated at the free ends of the adhesive layer; therefore, the presence of the adhesive fillet at the adhesive free ends was taken into account. The tee joints were analysed for two boundary conditions: a rigid base and a flexible base. In addition, each boundary condition was analysed for four loading conditions: tensile, compressive, and two side loadings. The stress analysis showed that both side loading conditions resulted in higher stress levels in the joint region in which the vertical plate and supports are bonded to each other, as well as in the adhesive layer in this region for both rigid and flexible base boundary conditions. In adhesively bonded joints, the joint failure is expected to initiate in the adhesive regions subjected to high stress concentrations; therefore, the peak adhesive stresses were evaluated in these critical regions. In the case of the rigid base, the peak adhesive stresses occurred at the corner of the vertical plate, which was bent at right angles, for the tensile and compressive loading conditions, and in the adhesive fillet at the upper free end of the vertical adhesive layer-vertical support interface for both the left and the right side loading conditions. However, in case of the flexible base, the peak adhesive stresses occurred in the adhesive fillet at the right free end of the horizontal adhesive layer-horizontal support interface for the tensile, compressive, and the right side loading conditions, and in the vertical adhesive fillet at the upper free end of the vertical adhesive layer-vertical support interface for the left side loading condition. Furthermore, the adhesive stresses showed a nonlinear variation in the direction of the adhesive thickness for all boundary and loading conditions. The left side loading condition, among the present loading conditions, which results in the highest adhesive stresses is the most critical loading condition for both boundary conditions. The effects of horizontal and vertical support lengths on the peak adhesive stresses and on the joint stiffness were also investigated and the appropriate support dimensions relative to the plate thickness were determined based on the stress and stiffness analyses.