液化气体运输半挂车有限元分析及强度评定

应用有限元软件ANSYS建立液化气体运输半挂车整体模型,在几种运输载荷情况下,分别采用等效压力法和当量密度法进行应力分析,对应力集中位置进行应力分类并进行强度评定,确保半挂车满足运输安全要求。     

关于非标鞍座包角的探讨

通过对卧式容器的非标鞍座进行应力计算,分析相关应力随鞍座包角的变化趋势,得出包角小于120°的鞍座也可以使用的结论。自编计算程序,可对任意包角的鞍座进行强度校核。     

大型设备多鞍座卧式水压试验的力学分析

由于基础承重能力限制等原因,大型塔设备通常需要进行卧式水压试验。以一台进行非均布多鞍座卧式水压试验的塔设备为例,通过Zick法和有限元法求得了鞍座的约束反力和壳体的最大应力,对计算结果进行了比较,并对最大应力的出现位置、产生原因和组成成分进行了分析。此外,对试验压力和不均匀沉降对设备应力的影响进行了研究,指出了考虑试验压力的必要性,并分析了不均匀沉降对壳体应力的影响程度和影响机理。     

气体膜分离器中心管应力分析

建立了中心管计算模型,并对模型进行了应力分析,得出中心管危险截面在中心管上部区域的第一个开孔处,最大应力发生在危险截面与管道中性面相交的位置上。根据应力强度限制标准并考虑安全裕度得出中心管壁厚随压力变化的规律,这一规律可用于指导膜分离器中心管的设计。     

基于ANSYS的埋地热油管道弯管附近应力失效研究

研究了埋地热油管道在结构-热耦合应力作用下失效原因及锚固墩位置对其应力的影响。采用ANSYS对埋地热油管道进行应力模拟计算,得出在结构-热耦合应力作用下管道弯管处当量应力分布情况,并对不同角度的弯管进行结构-热耦合应力对比分析,得出不同角度弯管位置的应力数值,绘制变化曲线。同时改变弯管附近锚固墩位置,计算得出弯管处应力变化云图。结果显示,弯管处的最大当量应力随着角度的增加而逐渐减小,且调整锚固墩位置可进一步消减管道处最大当量应力,为防止埋地热油管道泄漏事故发生提供理论依据。     

荷载作用下膨胀压缩机组用输气管道三维数值模拟研究

以某膨胀压缩机组用输气管道为研究对象进行三维数值模拟方法的研究。考虑到输气管道的结构特点和输送的介质特征,在荷载分析的基础上,依据经典理论进行了管道的力学分析,建立了管道的三维数值模型,对内压作用和地基沉降下的管道变形与力学状态进行了数值模拟,分析并得到管道应力随地基沉降量的变化规律。结果表明:应用该方法可以比较真实地模拟出管道的应力和变形分布规律,确定管道的薄弱部位,为管道的现场施工、实时监测和安全性分析提供有价值的参考意见。     

高压氨分离器应力分析评定

基于ANSYS Workbench 16.0分析平台,计算了多层包扎式高压氨分离器的筒体应力,通过线处理法对应力进行均匀化和当量线性化处理,依据JB4732为标准进行应力分析与强度评定。分析结果表明:多层包扎式筒体在高压情况下受力状况良好,应力评定满足规定,这说明在给定工况下,该高压氨分离器强度符合要求,能够安全运行,为工程应力分析及应力评定提供参考。     

对《在用工业管道定期检验规程》(试行)几个问题的探讨

在用压力管道检验应该在保证管道安全性能和使用性能的前提下,在检验内容、项目、方法及安全等级评定诸方面具有科学性和可操作性。本文通过对《在用工业管道定期检验规程》的学习和实践体会,对规程在线检验中的位置与变形情况检查,蠕胀测点检查;全面检验中的管道结构检查、管道材质检查、耐压强度校核、管道应力分析;安全状况等级评定中的材料劣化和损伤、未焊透和未熔合等问题表述了作者自已的看法。     

基于ANSYS的液氯罐式集装箱有限元分析

以1CC型液氯罐式集装箱为例,建立有限元分析模型。将介质惯性力处理为静载荷和动载荷,分别采用等效质量法、平均压强法和冲击载荷法三种不同加载方式对1CC型液氯罐式集装箱进行有限元分析计算。结果表明,三种不同加载方式对罐体本身的应力强度差别较小,而对于罐式集装箱的框架和鞍座应力强度的差别则很大。     

高压工业管道焊缝应力分析和强度评定

某化工企业管道管件弯头与三通焊缝连接处存在焊缝未焊满的情况,基于弹性分析策略评价该管道和焊缝处高应力区的应力强度,并分析管道和焊缝温度场与应力场随时间变化的关系,得到以下结论:在使用工况下管道管件和焊缝处满足应力强度要求,在设计工况下管道管件满足应力强度要求,管道焊缝处在50 s时刻强度评定为不合格;为了保证管道在设计...     

安装刮吸泥机前后污水沉降罐受力分析

针对污水沉降罐在安装刮吸泥机后的受力可靠性问题,建立了简化力学模型和三维弹塑性有限元模型。利用ANSYS软件计算了沉降罐在改建前、假设只有刮吸泥机载荷作用和改建后3种受力状态下的等效应力和位移的分布,以及滚轮位于导轨不同位置时整个装置的受力情况。结果表明,导轨和支撑肋板承担大部分的刮吸泥机载荷。     

Assessment of temperature-dependent fracture behavior with different fracture mechanics concepts on examples of unoriented and cold-rolled polypropylene

Applicability of different fracture mechanics concepts, including linear elastic fracture mechanics (LEFM), equivalent energy concept, and elastic-plastic fracture mechanics (EPFM), to assessing the temperature-dependent fracture behavior was compared using examples of an unoriented and a cold-rolled polypropylene under quasistatic and under dynamic loading. Under quasistatic loading, the fracture toughness values were determined from the recorded load versus load-line displacement curves on compact tension (CT) specimens. Fracture toughness values under dynamic loading were determined from the recorded load versus deflection curves on single edge-notched bend (SENB) specimens. In spite of its simplicity as an engineering design parameter, on the basis of the LEFM concept, the stress intensity factor K can only be validly used in a limited temperature range. Instead, the EPFM parameters (i.e., the J integral and the crack opening displacement (COD) concepts) can be applied over a wider temperature range. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1237–1249, 1997     

Analysis of a pull-out test with real specimen geometry. Part II: the effect of meniscus

This paper continues our study on the platelet model of the pull-out specimen, in which the matrix droplet shape is approximated by a set of thin parallel disks with the diameters varying along the embedded fiber. Using this model, the fiber tensile stress and the interfacial shear stress profiles were calculated for real-shaped matrix droplets, including menisci (wetting cones) on the fibers, taking into account residual thermal stresses and interfacial friction. Then, these profiles were used to numerically simulate the processes of crack initiation and propagation in the pull-out test and to obtain theoretical force-displacement curves for specimens with different embedded lengths and wetting cone angles. Our simulations showed that the interfacial crack in real-shaped droplets initiated at very small (practically zero) force applied to the fiber, in contrast to the popular ‘equivalent cylinder’ approximation. As a result, the equivalent cylinder approach underestimated the interfacial shear strength (IFSS) value determined from the pull-out test and at the same time overestimated the interfacial frictional stress; the smaller was the wetting cone angle, the greater the difference. We also investigated the effects of the embedded fiber length and interfacial frictional stress in debonded areas on the calculated IFSS. The simulated force–displacement curves for the real-shaped droplets showed better agreement with experimental curves than those plotted using the equivalent cylinder approach.     

鞍座参数对双鞍座卧式容器承载能力的影响

针对鞍座参数对卧式容器承载能力的影响进行了研究.采用有限元方法,计算了不同鞍座位置条件下,双鞍座支撑的卧式容器筒体应力的分布,得到了影响鞍座处筒体环向压缩应力的主要因素,初步探讨了垫板对鞍座处峰值应力的影响.研究结果表明:对于薄壁的卧式容器,应该使鞍座尽量靠近封头,而对于壁厚较大的卧式容器来说,最好将其设置在A/L=0.25的位置处;鞍座的宽度、包角以及鞍座反力都是影响鞍座处筒体上最大环向压缩应力的主要因素,在此基础上,提出了鞍座处筒体上最大环向压缩应力的计算公式.鞍座垫板对降低鞍座处筒体上峰值应力具有一定的效果,对于给定的垫板伸出角,有一个最佳垫板厚度值.这些研究结果为卧式容器的设计提供了参考依据.     

Analysis of a pull-out test with real specimen geometry. Part I: matrix droplet in the shape of a spherical segment

We compared two models of the pull-out specimen – the ‘equivalent cylinder’ and the platelet models in which the matrix droplet is represented as a set of thin parallel disks with the diameters varying along the embedded fiber to approximate the real droplet shape. Analytical expressions for the profiles of the fiber tensile stress and the interfacial shear stress have been derived for the matrix droplet in the shape of a spherical segment, including the effects of residual thermal stresses and interfacial friction. Using these expressions, we analyzed the process of crack initiation and propagation in the platelet model and investigated the effect of the specimen shape on the force–displacement curves. The interfacial stress near the loaded fiber end in the platelet model is higher than in the equivalent cylinder model, which gives rise to earlier crack initiation and smoother shape of the force–displacement curve. As a result, the calculated interfacial shear strength values may be underestimated by 10–20%, if the equivalent cylinder is used instead of the real droplet shape. A method of correction to the equivalent cylinder model in order to avoid this underestimation is proposed.     

Determination of the R-Curve from the Strength—Indentation Load Relation

Strength as a function of indentation load has been measured to evaluate toughness versus crack size curves (i.e., R -curves) of ceramics. In the past, this evaluation is achieved by generating a family of global stress intensity versus crack size curves (i.e., K -curves) at each indentation load and its corresponding strength, and then fitting an envelope of tangency points to these curves. This envelope yields the R -curve. A methodology is proposed in the present study to define the point in the K -curve at which the R -curve intersects. This methodology complements the conventional "tangency condition" approach in determining the R -curve from the experimental strength-indentation load relation.     

Determination of the In Situ Fiber Strength in Ceramic-Matrix Composites from Crack-Resistance Evaluation Using Single-Edge Notched-Beam Tests

A model for the single-edge notched-beam (SENB) test is presented which allows the load–displacement curve of fiber-reinforced ceramic-matrix composite (CMC) specimens to be calculated using the crack-opening function. This function considers the effects of the main parameters of the composite components that govern the fracture of the composite (e.g., fiber strength and interfacial properties). Then, in an experimental study, the SENB curves of an oxide–oxide composite are measured in the as-processed state and after exposure at elevated temperatures. Comparison between the measured and calculated SENB curves indicates that the characteristic loss of the maximum load in the SENB curves due to the annealing is caused by the corresponding reduction of the in situ fiber strength. This method then is proven to be an excellent tool to evaluate the actual fiber strength in CMCs, which is, otherwise, barely measurable. It will be shown that the SENB test is very much qualified for a proper investigation of the relationship between in situ fiber strength and composite strength (the maximum SENB load), because of the limited influence of other parameters (Weibull modulus of the fiber strength and the friction coefficient) on the maximum SENB load.     

基于冲压试验的聚乙烯力学性能预测

通过对5种不同曲率半径的高密度聚乙烯(PE?HD)圆棒试样进行单轴拉伸试验,重点分析了曲率半径对工程应力?位移曲线的影响;同时对PE?HD平板试样进行冲压试验,分析了压头直径和冲压速度对载荷?位移曲线的影响;建立了3种基于冲压载荷预测PE?HD单轴屈服应力的经验公式.结果表明,同一拉伸速度下,屈服强度随曲率半径的减小而...     

聚丙烯纤维混凝土-沥青混凝土复合切口梁弯曲韧性研究

对旧沥青路面进行铣刨处理后,加铺的白色罩面层多采用纤维混凝土,为了研究聚丙烯纤维和沥青层表面凿毛处理对复合切口梁弯曲韧性的影响,采用掺加聚丙烯纤维和对沥青层表面凿毛处理的高性能混凝土-沥青混凝土(AC-13)复合切口梁进行三分点加载试验,得到了荷载与挠度、裂缝张开距离之间的关系曲线,并对复合梁的抗折强度、能量吸收值、等效抗弯拉强度进行了计算.结果表明,聚丙烯纤维与凿毛处理均能提高复合切口梁的弯曲性能,聚丙烯纤维的掺加提高了复合梁的抗折强度,每当聚丙烯纤维掺量的增加0.45时,feq1、feq2大约增加0.035 MPa,混凝土的能量吸收值也增加8%左右;凿毛处理大幅度提升了等效弯拉强度,等效弯拉强度feq1、feq2分别提升了0.05 MPa、0.03 MPa,凿毛处理对feq1的提升效果比feq2更明显,使得复合梁的能量吸收值平均提升了20%.     

桩-桩帽-系梁复合结构加固路基特性研究

高强预应力混凝土管桩(PHC管桩)加固深厚软土地基时,桩帽偏心会降低桩承式路基的整体加固效果,影响路堤稳定性。本文以某高速公路桩承式路堤工程为依托,利用有限元软件ABAQUS建立桩承式路堤三维数值模型,研究了桩帽向路基外侧不同偏心距对路堤边坡稳定性的影响,并提出桩-桩帽-系梁复合结构改进措施。研究结果表明:桩帽偏心时桩体荷载分担降低,地基沉降和侧向位移显著增大,桩土差异沉降增大,边坡稳定性降低,桩帽极限偏心距离为10cm;桩帽用系梁相连后,地基土沉降和差异沉降均明显减小,边坡稳定性提高,桩-桩帽-系梁复合结构改进措施有效。