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加氢压缩机气缸盖螺栓断裂故障分析 总被引:1,自引:0,他引:1
通过成份分析、硬度测试、金相检验和断裂分析等方法,对炼油厂加氢压缩机气缸盖螺栓的断裂故障进行了分析.结果表明,螺栓断口具有明显的疲劳断裂特征,由于螺纹存在加工误差,使得螺纹根部应力集中系数加大,较大的螺栓预紧力是最终导致螺栓断裂的主要原因. 相似文献
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拉伸及疲劳载荷对低碳钢磁记忆信号的影响 总被引:13,自引:1,他引:13
为探索金属磁记忆现象的物理本质,深入研究载荷对磁记忆检测信号的影响,在MTS810型液压伺服试验机上对低碳钢板状试件分别施加静载拉伸载荷及拉-拉疲劳载荷,采用EMS-2003型金属磁记忆与涡流诊断仪检测加载过程中磁记忆信号的变化。结果表明:施加载荷前试件表面的初始磁状态不同;加载过程中两种加载方式均使磁记忆信号曲线由初始的随机分布转变为较有规律分布,静载拉伸试件弹性变形阶段与塑性变形阶段的磁信号曲线具有明显差异,疲劳试验不同循环周次下磁信号曲线相似;断裂瞬间断口处磁信号激变,两端极性相反;疲劳加载过程中过零点由初始磁状态的随机位置逐渐漂移集中在断口处。 相似文献
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往复机余隙腔螺栓断裂原因分析与处理 总被引:1,自引:0,他引:1
对炼油厂加氢装置联合氢气压缩机余隙腔螺栓断裂原因进行了分析,通过宏观检查,强度分析,对螺栓材料成分分析,金相检验,硬度检测,对螺栓断口及螺纹进行电镜检验,得出机械加工不当是导致螺栓断裂主要原因,并提出了解决措施和预防方案. 相似文献
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对42CrMo钢缺口试件施加压扭复合动态载荷,进行疲劳试验和金属磁记忆在线检测。试验结果表明,金属磁记忆检测技术在压扭动载疲劳损伤检测中是可行的。采集的磁记忆信号切向分量能够表征整个疲劳过程中试件各部位的应力集中程度及其变化趋势。提取了磁记忆信号特征参量k max,通过对特征参量k max的分析,实现了对试件缺口附近的应力集中程度的定性与定量表征。建立了k max的疲劳损伤模型,对试件的疲劳寿命进行了初步预测,为钻具的工况检测提供试验依据。 相似文献
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针对螺栓联接结构中螺栓孔位置处裂纹损伤实时监测的需求,采用强化磁记忆检测技术,搭建了基于GMR传感器的环螺栓孔阵列的低周疲劳裂纹产生和扩展监测装置,对螺栓孔孔边的状态进行实时在位监测,并通过分析监测信号对拉伸试件的损伤断裂位置进行定位。结果表明,该装置可以有效预测裂纹萌生及试件断裂的位置,并且在损伤出现的早期阶段磁异变信号更加敏感。 相似文献
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To study the characteristics of metal magnetic memory (MMM) signals of different steels during tensile test, static tension tests were applied to 30 pieces of Q235 and 16MnR base metal and welded specimens. During the various deformation periods, MMM signals are tested, and micrometallographic is observed. Furthermore, the derivative of magnetic intensity (dHp/dx) is analyzed by mathematical and statistical methods to study the macro and micro corresponding relationships and difference among magnetic signals. Results show that despite the different magnetic intensity (Hp) curves of different materials, their dHp/dx patterns in the yielding and necking stages are the same; welded specimens have the similar magnetic signal curves with their base metal, and the welded structure does not interfere with its Hp distribution; different materials have their unique zero point (Hp=0) before being fractured, which is independent of the fracture location; there is a direct relationship between the intragranular slip and the changes of magnetic signals, which indicates the uneven plastic deformation. 相似文献
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中碳钢疲劳试验的磁记忆检测 总被引:5,自引:0,他引:5
金属磁记忆检测技术是无损检测领域新兴的检测手段,由于其具有独特的检测理念,被期望能够在铁磁性金属构件早期损伤阶段即进行准确的无损检验工作,但是该技术仍处于发展初期,需要开展大量基础性研究工作来探究其机理和应用范围.通过不同加载方式的疲劳试验,研究疲劳载荷作用下中碳45钢试件磁记忆信号的变化情况.研究表明:指定疲劳方式下试件磁记忆信号随疲劳循环次数增加呈现规律性变化;磁记忆检测高载疲劳损伤的能力优于低载疲劳损伤,对含缺陷试件疲劳损伤的判别强于无缺陷试件.分析磁记忆现象的成因,认为疲劳作用促使试件受载薄弱区域位错应力场形成和成长,使该区域磁畴分布明显异于正常区域,进而以特殊磁信号形式表现出来.试验表明:磁记忆检测技术有助于评判金属材料的损伤情况,但评判的准确性会受到加载条件和试件形貌等多种因素的影响. 相似文献
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磁记忆检测作为早期诊断的新兴技术已受到国内外无损检测界广泛关注,但现有的磁记忆检测技术主要以单一方向上的漏磁场信号(法向分量)来进行判断,没有充分利用磁记忆检测信号的全部信息,容易出现漏检、误检等问题。针对该项检测技术的不足,介绍一种将磁记忆检测信号法向分量存在过零点和切向分量存在极大值的特征曲线联合应用的二维检测方法。该方法同时采集法向和切向的磁记忆信号,利用矢量合成法获取切向最大值,然后求取法向、切向分量一阶微分后合成的李萨如图,利用李萨如图的面积对应力状态进行分析,并将自主研制的磁记忆二维仪器应用到工程实践中。实践证明,该二维系统及检测方法能高效地对应力集中进行判定,可望成为实现磁记忆检测定量分析的新方法。 相似文献
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Yiliang Zhang Ruibin Gou Jimin Li Gongtian Shen 《Frontiers of Mechanical Engineering in China》2010,5(2):226-232
To study the characteristics of metal magnetic memory (MMM) signals of different steels during tensile test, static tension
tests were applied to 30 pieces of Q235 and 16MnR base metal and welded specimens. During the various deformation periods,
MMM signals are tested, and micrometallographic is observed. Furthermore, the derivative of magnetic intensity (dH
p/dx) is analyzed by mathematical and statistical methods to study the macro and micro corresponding relationships and difference
among magnetic signals. Results show that despite the different magnetic intensity (H
p) curves of different materials, their dH
p/dx patterns in the yielding and necking stages are the same; welded specimens have the similar magnetic signal curves with their
base metal, and the welded structure does not interfere with its H
p distribution; different materials have their unique zero point (H
p = 0) before being fractured, which is independent of the fracture location; there is a direct relationship between the intragranular
slip and the changes of magnetic signals, which indicates the uneven plastic deformation. 相似文献
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根据理论公式及试验现象分析了R134a冰箱压缩机气缸头部积炭现象产生的原因,积炭对压缩机性能的影响,从降低气缸头部温度、提高冷冻油热稳定性,以及根据压缩机使用工况合理选用压缩机角度,提出了减少积炭现象的方法和措施。 相似文献