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某柴油机出现了喷嘴断裂失效现象,通过对其进行理化分析及金相组织分析,找出了喷嘴断裂的原因是零件热加工工艺不当,渗碳层深度不均匀,颗粒状碳化物分布不规则,渗碳层氢脆,出现明显的晶粒粗大的过热组织缺陷,且阀座处的应力集中安全系数偏低。 相似文献
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启喷压力与针阀落座冲击应力间关系和理论分析 总被引:1,自引:0,他引:1
本文作者详细地评述了针阀落座冲击应力的影响因素,以及目前用来计算座面冲击应力的公式对不同类型喷嘴的适用性。通过对启喷压力与针阀落座冲击应力之间关系的分析,根据应力波理论推导了新的针阀座面冲击应力的计算公式。该公式可适用于各种不同类型的喷嘴,从而为喷嘴的设计和选择合适的启喷压力提供了可靠的理论依据。 相似文献
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对某母管制背压式汽轮机机组的主汽-调节阀在定参数快速冷启动过程中的结构强度进行了研究,利用ABAQUS软件建立了主汽-调节阀三维有限元模型,得到主汽-调节阀在启动过程中的温度场和瞬态应力场,将主汽阀测点位置温度计算值与测量值进行了对比,并分析了不同主汽阀开度对主汽阀阀座应力交变行为的影响。结果表明:主汽阀测点位置温度计算值与测量值吻合较好;主汽阀阀座在启动过程中出现了明显的应力交变现象;通过改变主汽阀开度可以有效缓解主汽阀阀座的应力交变现象,降低主汽阀阀座疲劳损伤。 相似文献
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大型罐体运输车结构强度和刚度的有限元分析 总被引:1,自引:0,他引:1
《内燃机与动力装置》2016,(1):46-50
以大型罐体运输车为研究对象,对其进行有限元分析,从而确定该运输车结构的薄弱和危险部位,以便对其进行结构优化改进。首先,利用ANSYS Workbench平台建立大型罐体运输车有限元模型;其次,根据工程实际中的受力和约束情况,为其施加合理约束和载荷;最后求得该大型罐体运输车各个部件的变形和应力情况。计算表明,罐体运输车最大应力点在端部支架处,最大应力值为250MPa,安全系数为2.196,处于安全范围。论文还利用材料力学的知识对罐体的中间横截面所受到的最大应力进行了强度计算,验证了有限元计算的准确性。 相似文献
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D6114ZQ柴油机活塞三维有限元分析及其结构改进 总被引:2,自引:0,他引:2
杨俊武 《柴油机设计与制造》2000,(1)
通过对D6114ZQ柴油机活塞在最高爆发压力和最大侧压力作用下的三维有限元分析,获得了其温度场和应力分布情况等,根据分析结果,对活塞工作的疲劳安全系数进行了计算。计算结果表明:侧压力的作用及销座下部与裙部侧壁间过渡处的应力集中是影响活塞裙部裂纹产生的主要原因,据此,提出了相应的结构改进措施。 相似文献
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柴油机喷嘴喷孔内气液两相湍流场三维数值模拟 总被引:7,自引:0,他引:7
柴油机喷嘴内部空穴流动是影响喷雾特性极为重要的因素。在开发了喷嘴流动区域三维实体参数化生成软件的基础上,对完全发展了的空穴流动建立起三维空穴两相流动数学模型,提出将计算区域的出口边界延伸至气缸内部,以减小出口对喷孔内部求解区域的影响。对多孔垂直喷嘴进行了喷孔内部空穴两相湍流流动的三维数值模拟,得出喷嘴内部燃油流动的压力降基本发生在喷孔入口处,喷孔入口锐边过渡,使得该处必定出现空穴现象,且会延伸至喷孔出口,增加液流紊乱,引起燃油在喷孔出口的初次雾化。 相似文献
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4100QBZ柴油机高压共轨系统喷油嘴匹配及优化 总被引:1,自引:0,他引:1
为将BOSCHCR高压共轨系统应用在4100QBZ柴油机上,进行了BOSCH喷油嘴与4100QBZ柴油机燃烧室的匹配。遵循油束沿燃烧室轴向和径向分布均匀匹配的原则,计算了喷油嘴的结构参数;用KIVA软件建立喷油嘴和燃烧室燃烧网格模型,优化喷油嘴参数。用等圆弧分布和等体积的方法得到四组BOSCH喷油嘴方案;对不同喷油嘴进行燃烧计算,以最高燃烧压力和燃油消耗率为指标,选取合理的喷油嘴参数。 相似文献
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基于亚克力(PMMA)透明喷油嘴内流动的试验研究结果,构建了透明喷油嘴的三维模型,通过流固耦合(FSI)方法对透明喷油嘴的固体变形及应力分布情况进行模拟研究。模拟结果表明,透明喷油嘴的变形与应力均主要集中在压力室及喷孔入口处,其中压力室入口处应力最大,超过胶粘剂的粘黏强度是造成透明喷油嘴产生裂缝失效的主要原因。同时分析了孔内流体体积随入口压力的变化情况及固体变形对孔内流体流动特性的影响。结果表明:在使用透明喷油嘴喷油时,固体产生的变形会造成在针阀关闭后柴油完全断流的时间较实际喷油嘴有所延后,最后喷出的质量也略大,导致试验过程中在喷油结束后存在较长时间的滴落现象。 相似文献
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发动机缸体瞬态强度分析 总被引:1,自引:0,他引:1
针对发动机缸体结构复杂,工作过程中受到多种交变激振力作用的特点,建立了较详细的缸体瞬态强度分析有限元模型,模拟了缸体在发动机工作过程中的动态强度变化历程。得出:缸体与缸盖及变速器相连的紧固螺栓孔周围的整体应力水平较高,但随发动机工作负荷变化的波动量较小;缸体主轴承座周围动态应力和变形成分较高,且随发动机工作负荷变化的波动量较大;而缸体两侧壁的动态变形和应力与静态变形和应力水平较低。研究表明:在建模时考虑活塞和曲轴对缸体的接触作用,合理简化缸体结构,准确深入揭示工作过程中缸体的动态强度随时间的变化,为缸体动态结构强度设计提供可靠依据。 相似文献
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《International Journal of Pressure Vessels and Piping》2001,78(7):485-493
This paper contains a stress analysis of a cylindrical pressure vessel loaded by axial and transverse forces on the free end of a nozzle. The nozzle is placed such that the axis of the nozzle does not cross the axis of the cylindrical shell. The method of finite elements was applied to determine the state of stress in the cylindrical shell. The values obtained for stress in the nozzle region were used to determine the following: envelopes of maximum stress values; maximum values on these envelopes; and distances between maximum values on envelopes and the outer edge of the nozzle. Algebraic functions were determined, which enable easy and simple determination of these numerous stress values. The stress values obtained from the algebraic function were within −12.5 and +12.8% of those from finite elements. The difference between stresses deduced from strain gauge readings on experimental and calculated stresses was a maximum of 12%. 相似文献
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W. Brocks D. Noack H. Veith H.-H. Erbe 《International Journal of Pressure Vessels and Piping》1982,10(3):219-234
The paper presents the results of an elastic-plastic three-dimensional finite element analysis for a nozzle corner crack in a pressurised reactor test vessel. The calculations were performed by the finite element program ADINA incorporating von Mise's yield condition and isotropic hardening. The crack plane was taken parallel to the axis of the vessel and the crack front straight and perpendicular to the symmetry line of the nozzle corner in order to obtain the worst position for a nozzle corner crack. The calculations were performed up to that pressure level where general yield of the ligament in the nozzle corner section takes place.For the chosen crack length, which is relatively small in comparison to the ligament, the crack opening stress as well as the crack opening displacement have a maximum in the centre of the crack. The differences between the maximum and minimum values along the crack front increase rapidly in the plastic range when the pressure load is raised above half of the general yield pressure. The results of the finite element analysis are compared with figures obtained from analytical procedures of elastic-plastic fracture mechanics. 相似文献
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The main purpose of this paper is to perform a comparative study of strength behavior for cylindrical shell intersections with and without pad reinforcement under out-of-plane moment loading on nozzle. Three pairs of full-scale test vessels with different d/D ratios were designed and fabricated for testing and analysis. A three-dimensional nonlinear finite element numerical analysis was also performed. The maximum elastic stress for each vessel under per unit moment on nozzle is provided. The plastic limit moment on nozzle is obtained by load–displacement and load–strain curves for each test vessel. The results indicate that the effect of pad reinforcement on decreasing maximum elastic stress and increasing plastic limit load is obviously effective. The study results will serve as the available data for understanding the usefulness of pad reinforcements and as the basis for developing an advanced design method by limit analysis for pad-reinforced cylindrical vessels under external loads on nozzle. 相似文献