带大孔径接管锥壳变径段应力的数值计算和强度分析

针对带有大孔径接管锥壳变径段结构不连续应力和局部应力的计算与强度分析问题,根据其结构特点,选择研究对象,处理边界条件;应用有限元理论和方法,建立数值计算模型;采用ANSYS程序,进行网格划分和数值计算,获得变径段部位详尽的位移场和应力场;在应力分析的基础上,根据分析设计的思想对应力进行分类和强度评定。应力计算结果表明,变径段上多个部位产生了较高的局部应力,强度评价结果表明,锥壳变径段的强度满足要求。     

蒸汽过热器简体与接口不连续区热应力分析

通过使用ANSYS/Workbench软件对压力设备建模并进行热应力耦合分析,通过模型的改进,确保模型结构符合设计需要,对设备最大应力处进行线性化分析,确保应力结果符合标准应力强度要求,从而达到利用软件指导现有设备设计及操作的目的,同时也确定了在模型建立中模型的合理简化方式.     

蒸汽过热器筒体与接口不连续区热应力分析总结

通过使用Ansys Workbench软件对压力设备建模并进行热应力耦合分析，通过模型的改进，确保模型结构符合设计需要，对设备最大应力处进行线性化分析，确保应力结果符合标准应力强度要求，从而达到利用软件指导现有设备设计及操作的目的，同时也确定了在模型建立中模型的合理简化方式。     

氨合成塔封头结构设计与应力分析

按GB 150规范对氨合成塔的封头进行了结构设计和强度校核；利用ANSYS软件建立封头模型并对该模型进行了应力分析;选择封头对应处的ANSYS计算结果与经典公式计算结果作对比,检验了ANSYS结果的正确性.     

基于Abaqus软件的轮胎有限元模型建立及仿真分析

基于Abaqus软件建立轮胎有限元模型,对305/75R24. 5全钢载重子午线轮胎的充气外缘尺寸、胎肩应力分布、带束层应力分布、胎圈与轮辋接触应力分布进行预测分析。有限元仿真结果表明:轮胎的充气外缘尺寸符合国家标准要求,静负荷状态下沉率满足轮胎的整体刚度要求;胎肩应力最大处位于3~#带束层端部;在充气和静负荷状态下,2~#带束层的应力均小于3~#带束层;胎圈与轮辋过盈配合处及其周围应力较大。     

基于AWE的阀体强度分析与结构优化设计

在ANSYS Workbench集成平台下,建立阀体结构的有限元分析模型,分析阀体结构的强度,得到了阀体等效应力的分布,进而找出了结构的薄弱环节。从阀体安全、可靠和经济的角度出发,针对阀体应力集中的现象,采取以阀体集中应力处的最大等效应力为目标函数,结合阀体壁厚和阀体流道壁厚进行有限元分析和优化设计,同时结合应力敏感度分析,为提高阀体强度提出指导意见,得到了理论最优的阀体结构尺寸。     

基于有限元法的二甲苯吸附塔底封头补强设计及应力分析

利用ABAQUS分析软件建立了二甲苯吸附塔整体的三维有限元模型,分析了扩能改造后吸附塔在操作工况下的整体应力分布,发现底部封头局部应力过高,易发生强度失效。因此,提出在底部封头与中心管连接的支撑区域外壁加设环形补强板进行补强,并通过有限元分析对比了不同厚度补强板的补强效果。结果表明:采用的补强板结构能有效减小底部封头应力水平,应力分布得到改善,各部分应力强度评定均合格,为二甲苯吸附塔的工程改造提供了依据。     

100m跨下承式钢管混凝土系杆拱桥设计

本文以某跨江桥梁为背景,详细论述了100m跨下承式钢管混凝土系杆拱总体布置及构造特点;建立主桥有限元分析模型,采用联合截面与双单元双肢截面法对主桥钢管混凝土拱肋进行了对比分析;通过对拱脚节点建立三维局部分析模型分析最不利应力区域,最终进行了配筋设计;同时分析了运营状态桥梁的稳定性,为类似桥梁提供参考。     

基于有限元法的旋转挤压式污泥脱水机整体结构强度分析

采用有限元法,对新型旋转挤压式污泥脱水机进行力学分析。考虑到对各构件分别建模分析时难以确定载荷和边界条件,建立了整体结构有限元模型,得到了von-Mises应力和变形分布,并进行了强度和刚度校核。结果表明:对于所分析的污泥脱水机,最大应力发生在挡门与外隔板接触的局部区域,大小为187.2 MPa,最大位移出现在支撑板外侧,大小为0.016 mm,强度和刚度都满足要求。     

两种焦炭塔裙座连接结构应力对比分析

以某石化公司焦炭塔为研究对象,首先分析焦炭塔受力情况,进而对比新型板焊结构和整体锻件结构的优劣性,为此后大型焦炭塔裙座连接部位的结构设计提供参考。两种结构的对比主要围绕结构内应力分布的对比。运用有限元分析软件ANSYS建立新型板焊结构以及整体锻件的二维模型,对结构只受重力和内压、升温、降温三种工况分别进行分析,分别得出在三种工况下结构内的机械应力和热应力。根据分析结果,对比两种结构的等效应力强度大小和应力集中点的位置。通过对比,可以得出以下结论:新型板焊结构在三种工况下的最大应力均出现在上部角焊缝上方的塔体上,最大值达到371.5 MPa,是焦炭塔开裂的主要原因;整体锻件的最大应力出现在裙座与塔体连接的圆弧过渡处,最大值为273.3 MPa,应力分布状况要优于新型板焊结构。     

高温法兰连接结构的有限元模拟及安全评定

利用ANSYS软件分析了高温螺栓法兰连接系统在预紧、承压及热-机操作工况下的应力和变形行为,并基于强度分析和密封分析对螺栓法兰连接进行了安全评定.结果表明：不同工况下,应力具有相似的分布规律,法兰最大应力在螺母与法兰接触面的内侧,上、下法兰应力分布具有对称性;螺栓应力呈现拉弯组合形变,最大应力出现在由中间向两端第一个螺纹根部;垫片应力在各工况下均呈现为外大内小,密封面压力均大于满足密封要求的最小压紧力,法兰的转角均小于0.3°,满足法兰刚度要求,强度分析和密封分析均满足要求,具有良好的紧密性,给出了一种工程分析方法.     

Process-induced residual stresses in compression molded UHMWPE

Non-isothermal cooling during processing causes the development of residual stresses, which are analyzed for compression molded UHMWPE, and affects the dimensional stability. The development of thermal residual stresses was predicted using an incremental stress analysis that included temperature-dependent material properties. Strain gauges were used to measure the residual stresses as layers were removed from a molded disk using a Process Simulated Laminate (PSL) approach. The PSL technique has not previously been applied to a compression molded neat polymer. For initial surface cooling rates of ～ 11°C/min, the model predicted a compressive stress at the bottom surface of 14 MPa and a tensile stress near the center of 2.5 MPa and matched the experimental distribution well. Because the compressive residual stress was 70% of the yield strength (～20 MPa), a lower cooling rate was also tested (2.6°C/min). The maximum tensile and compressive stresses for this cooling rate were, 0.91 MPa and 2.5 MPa, respectively. The model demonstrated its use for predicting thermal residual stresses in compression molded parts, instead of trial-and-error experimentation. UHMWPE is shown to develop residual stresses continually from ～ 120°C to 23°C.     

Thermal Stresses in Circular Ceramic Rod Specimens Subjected to Sudden Radiative Cooling

The thermal stresses which result from sudden radiation heat losses in a ceramic circular cylinder were calculated by the finite-element method. It was shown that, for a given value of coefficient of thermal expansion and Young's modulus, the magnitude of the maximum stress increases with increasing emissivity and cylinder diameter and decreasing thermal conductivity. In terms of the initial temperature, T, the maximum stress was found to be proportional to T^x, with 3.3 ≤ x ≤ 3.5.     

Angle of Hertzian Cone Cracks

This paper discusses the difference between the experimentally observed angle of Hertzian cone cracks and the angle defined by the trajectories of the preexisting stress fields. It is argued that there is no reason why these angles should be the same, as has usually been assumed. A finite element method has been used to model the growth of cracks in the Hertzian stress fields. In this model, the crack is incrementally advanced along the direction of maximum strain energy release, as calculated by the evolving, rather than the preexisting, stress fields. For the modeled Hertzian indentation system, a cone crack is observed to grow, but at an angle which is significantly different from that defined by the normal to the maximum preexisting tensile stress. The angle of the cone crack, as grown in the model, is in excellent agreement with observations on experimentally grown cone cracks in glass, with the same Poisson's ration. It is proposed that, in general, cracks will grow along paths that result in the maximum release of strain energy. For asymmetric, nonuniform preexisting stress fields, such paths do not necessarily coincide with the normal to the maximum preexisting tensile stress.     

Effect of Spatially Varying Thermal Conductivity on the Magnitude of Thermal Stress in Brittle Ceramics Subjected to Convective Heating

The effect of a spatial variation of the thermal conductivity on the magnitude of the maximum tensile thermal stress in a solid circular cylinder subjected to sudden convective heating was calculated by finite element methods. The general results show that by lowering the thermal conductivity in the surface region of the cylinder, the magnitude of the maximum tensile thermal stress at the center of the cylinder is reduced significantly. The negative temperature dependence of the thermal conductivity in dielectric materials, which indirectly creates a spatial variation in thermal conductivity, also causes a significant decrease in the magnitude of the tensile thermal stresses, as demonstrated by a numerical example for aluminum oxide. It is also shown that a spatial variation in thermal conductivity can significantly affect the time to maximum tensile stress as well.     

Impact strength of polymers 2: The effect of cold working and residual stress in polycarbonates

The influence of cold working on the toughness improvement in glassy amorphous polycarbonates was studied. Cold working processes, namely rolling and. Steckel rolling were used to produce thickness reductions up to 40 percent in flat-strip specimens. The notched Izod impact strength and tensile properties were measured as a function of strip thickness reduction. It was shown that the toughness enhancement in polycarbonates cold worked to low thickness reductions was due to the residual stress state present as opposed to molecular orientation which becomes significant at higher degrees of cold work. Residual stress measurements were made by using the layer removal technique. Residual tensile stresses as high as 2100 psi were present in 1/4-in. cold-rolled polycarbonate at the surface. The maximum stress in the center of the specimen was 1100 psi in compression. The residual stresses at the surface decreased with increasing thickness reduction. The residual stress state for Steckel rolled. 1/2-in. polycarbonate was also measured and found to be more complex than for the thinner samples, The results demonstrated that surface tensile stresses and interior compressive stresses can produce large values of impact strength if the notch is to be machined after cold working. Thus, the values of impact strength measured from the notch Izod specimen are sensitive to the residual stress state in the polymer. This behavior is in contrast to earlier studies on thermally quenched material in which the material was quenched after notching. The thermal quenching produced surface compressive stresses which were also present at the notch tip. The presence of compressive residual stresses at the center of the notch suppressed the formation of a craze leading to toughness enhancement in cold worked polycarbonate strips. It is shown that by control of residual stresses in polycarbonate, strips at least 1/2 in. in thickness can be made to exhibit ductile failure in the notched Izod impact test.     

Adhesion of two elastic conforming solids with a single interface gap

The adhesive contact between a half-space with a single surface micro-groove and a flat half-space is investigated. Surface interaction is described by the Maugis–Dugdale adhesion model. The contact problem is reduced to a singular integral equation for a height of the interface gap, which is solved analytically. For evaluating widths of the gap and the adhesion zone, a system of two transcendental equations is obtained, which is solved numerically. Three stable equilibrium states are found. The gap width-applied pressure curves are characterized by discontinuities and hysteresis. The effects of the maximum groove height and the adhesive stress on the adhesive contact are studied. It is shown that the adhesion hysteresis is greater for smaller grooves and larger adhesive stresses.     

Mapping of stress distribution in woven‐fabric composites

Mapping of the stress distribution in composite materials, both at the fiber/matrix interface and in the composite constituents, is important to understand the material mechanical response. Stress mapping can help predict composite behavior under certain stresses especially failure or delamination. In this work, two analytical models were proposed to map the stress distribution at fiber, matrix and fiber/matrix interface utilizing the concept of stress superposition. The first model dealt with the fiber in the longitudinal direction considering axisymmetric conditions. The second model addressed the fiber stress distribution in the transverse direction. Experimental data from four‐point flexural tests of woven fabric composites was processed using the Graphical Integrated Numerical Analysis (pcGINA) to obtain the maximum stress in the target laminate and this value was used as the input for the two analytical models. The value for the maximum interfacial shear stress was calculated using the models and results were compared to pull‐out fiber test values obtained from literature. Good agreement was observed between the model calculations and the literature data. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

基于ANSYS的多孔板应力应变分析

通过利用大型非线性有限元软件ANSYS对18种不同开孔数的多孔板进行数值模拟和分析,得出：多孔板的最大等效应力主要发生在多孔板开孔区最外侧开孔的对称中心处.随开孔个数的增加,最大等效应力呈增大趋势;最大等效应力的大小主要取决于Z方向的最大应力;孔的排列情况对多孔板应力有影响.结果对多孔板的设计研究具有一定参考价值.     

Mathematical analysis of the pressure distribution in powder in equilibrium in a conical vessel

A mathematical analysis of the distribution of pressure (vertical stress) in powder mass filled in a conical vessel is presented, taking into account the variation of pressure with the distance from the axis of the cone. The free surface of the powder mass is assumed to be heaped. It is assumed that vertical stress and horizontal stress are interrelated by Rankine's law. From the equilibrium condition of powder mass a fundamental equation has been derived to determine the pressure as a function of both the depth and the distance from the axis of the cone. A solution satisfying the boundary condition at the free surface has been obtained. It is shown that the analysis fits the experimental curves of the distribution of vertical stress