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本文介绍了锅炉过热器对空排气管路的结构,以及排气管座开裂的宏观特征,从管座的结构、工作环境等方面进行了应力分析,分析认为该管座开裂的主要原因是振动疲劳应力及热应力的长期作用所致。并根据现场实际情况制定切实可靠的换管工艺方案。 相似文献
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针对某6缸发动机高镍铸铁排气管在试验过程中出现的裂纹故障,基于流固耦合方法,利用有限元分析软件对故障排气管进行温度场、应力场和低周热疲劳计算分析.计算结果表明,排气管应力幅值较大区域和低周热疲劳计算寿命较低区域均与试验过程中发生的裂纹故障位置相吻合;冷热冲击工况下较大应力幅值产生的塑性应变是造成排气管热疲劳的主要原因.... 相似文献
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王仁杰 《柴油机设计与制造》2018,(1):30-33,40
某轻型客车存在车内噪声大、振动比较剧烈的问题。车辆怠速时,后排区域噪声明显;车辆缓加速时,在某些转速下存在共振噪声。前期已通过试验,排除了动力总成悬置的影响。对可能产生的噪声来源——排气管吊挂,采用传递路径分析方法,通过采集与分析实车运行工况数据、测试从排气管吊挂至车内的噪声与振动频率响应函数,计算了各排气管吊挂输入的振动激励能量在整个问题中所占的比重,确定了排气管吊挂是导致车辆后排区域噪声和振动大的主要原因,并确定了对车内噪声与振动贡献最大的排气管吊挂位置。 相似文献
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针对某船用柴油机三层壁水套排气管内部衬管开裂的故障,对其进行结构优化,将原有的不锈钢冲压衬管改为铸造衬管,同时通过螺栓将衬管固定在水套排气管上。基于热机耦合方法,采用Abaqus软件对衬管进行温度场和低周疲劳分析,并对优化后的铸造衬管结构进行仿真验证。结果表明:优化后的衬管安装更加方便,且仅有一段衬管存在低风险,最低低周疲劳循环可达5 275次;优化方案有效地解决了柴油机三层壁水套排气管衬管开裂的问题,提高了柴油机的可靠性。 相似文献
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气缸盖在工作过程中受载复杂,包括装配载荷、热载荷和爆压载荷.因此,在有限元分析中需要采用热机耦合的方法才能得到可靠的计算结果.针对耐久性试验中出现的缸盖开裂问题,采用热机耦合方法计算分析了缸盖的温度场、应力场和高周疲劳安全系数.计算结果表明,缸盖确实因存在疲劳安全系数不足而导致开裂. 相似文献
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由于振动或者外部自然环境的影响,风力发电机组在运行过程中所承受的载荷不确定,导致风力发电机组疲劳问题很复杂。文章基于雨流计数法和Palmgren-Miner线性累积损伤理论,对在役机组各部件的疲劳损伤预估计算。结合机组实际运行数据和部件疲劳损伤的预估值,采用神经网络算法和K-Fold算法建立预测模型,利用该模型可有效预测同一风场其他非标杆机组的部件损伤。结果表明,疲劳损伤的预测误差精度可控制在3%以内,为及时调整相关控制参数和控制策略提供了可靠的依据,进而保证机组运行的稳定性,使风机达到最佳的疲劳寿命。 相似文献
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在发动机耐久试验过程中,某大型柴油机油底壳挡板焊缝处发生开裂,造成油底壳漏油故障。采用瞬态动力学仿真计算、振动测试等方法对油底壳进行分析研究。研究结果表明,焊缝的应力幅超出许用限值、焊接处振动大是造成油底壳开裂的主要原因。通过改变油底壳外形结构、增加加强筋的方式来提高油底壳侧壁刚度,以降低油底壳挡板焊缝处的应力幅和焊接位置的振动水平。改进后的油底壳通过验证试验,未发生开裂故障,说明改进措施有效。 相似文献
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《International Journal of Pressure Vessels and Piping》1998,75(1):1-5
After 23 yr of service, several circular fatigue cracks have been discovered at the bottom of the chest valve chamber in the actual (in existence) power station high pressure piping. Finite element analyses of transient thermal stresses, caused by power station startup, are carried out in this paper. The calculation results show good agreement between the theoretical locations of the maximum stresses and the actual locations of the cracks. There is also good agreement between theoretical evaluation and actual service life. A probabilistic approach to service life assessment is performed by assuming that the temperature change and fatigue properties of the chest valve material are distributed randomly. The idea of machining out of the cracks is examined here. Machining enables us to extend the power station component's life service. 相似文献
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针对某新型柴油机轴系扭振计算中曲轴扭振附加应力过大问题,对激励进行分析并开展扭转振动计算;尝试采取不同途径消减过大扭振合成应力。得到如下结论:当今柴油机强化指标不断提高,而CCS推荐的气体激励简谐分量幅值相对偏小,从安全角度出发,扭转振动计算时应按照柴油机厂提供的激励数据进行。共振区域的过大振动应力可通过确定主要贡献的谐次分量,调整节点位置部件参数的方法来消减;非共振区域的过大振动属正常的振动响应,可通过增强曲轴的抗扭振疲劳强度来适应,但其可行性应综合考虑柴油机设计因素。 相似文献
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由于柴油机结构的复杂性,在对其一些主要零部件进行强度分析时,采用传统的力学方法只能近似地反映其受力状况以及变形情况,远不能满足进一步分析的需要。而运用有限元法则可以大大地改善这种情况,本文运用有限元法针对某型柴油机排烟管由于振动引起的应力进行了探究,为分析在振动条件下零部件的强度提供了一种方法和途径。 相似文献
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柴油机连杆疲劳试验的数值模拟研究 总被引:1,自引:0,他引:1
结合某型柴油机连杆疲劳强度测试试验与结果分析,主要运用三维有限元数值计算方法和疲劳寿命预测理论,采用Abaqus有限元计算软件和FE-Fatigue疲劳寿命预估软件,对连杆疲劳耐久性试验进行了数值模拟。通过对比连杆疲劳试验与虚拟疲劳寿命预估结果,表明基于材料S-N曲线的疲劳寿命预估方法,在一定程度上能够对疲劳试验中连杆破坏的薄弱部位和疲劳寿命进行模拟与预测。最后,对影响连杆疲劳试验测试结果的一些主要因素做了进一步模拟与分析。 相似文献
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Mechanical damage, including dents and cracks to pipes, occurs frequently, mainly caused by operational activities and fabrication errors. Structural assessment of dented pipes with cracks is of importance, but reliability-based assessment is necessary to properly account for the uncertainties invloved. This paper proposes a new methodology for calculating the fracture strength of dented pipes with cracks. Comparisons between the predicted fracture strength based on the presented approach and test results are made and good agreement is observed. A fracture reliability model of dented pipes with cracks is predicted. Fracture reliability analysis of a damaged pipe is performed based on a design example and detailed parameter studies are also conducted. Calibration of the safety factor based on the reliability methods is carried out. 相似文献
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Rahul Mittal P.K. Singh D.M. Pukazhendi V. Bhasin K.K. Vaze A.K. Ghosh 《International Journal of Pressure Vessels and Piping》2011
A systematic experimental and analytical study has been carried out to investigate the effect of vibration loading on the fatigue life of the piping components. Three Point bend (TPB) specimens machined from the actual pipe have been used for the evaluation of Paris constants by carrying out the experiments under vibration + cyclic and cyclic loading as per the ASTM Standard E647. These constants have been used for the prediction of the fatigue life of the pipe having part-through notch of a/t = 0.25 and aspect ratio (2c/a) of 10. Predicted results have shown the reduction in fatigue life of the notched pipe subjected to vibration + cyclic loading by 50% compared to that of cyclic loading. Predicted results have been validated by carrying out the full-scale pipe (with part-through notch) tests. Notched pipes were subjected to loading conditions such that the initial stress-intensity factor remains same as that of TPB specimen. Experimental results of the full-scale pipe tests under vibration + cyclic loading has shown the reduction in fatigue life by 70% compared to that of cyclic loading. Fractographic examination of the fracture surface of the tested specimens subjected to vibration + cyclic loading have shown higher presence of brittle phases such as martensite (in the form of isolated planar facets) and secondary micro cracks. This could be the reason for the reduction of fatigue life in pipe subjected to vibration + cyclic loading. 相似文献