共查询到20条相似文献,搜索用时 15 毫秒
1.
Seung-Kee Koh 《Journal of Mechanical Science and Technology》1993,7(3):194-202
Residual stress analysis of an autofrettaged thick-walled pressure vessel containing an external groove was described in order
to calculate the stress concentration at the external groove. The autofrettage residual stress distributions of the external
grooved thick-walled pressure vessel were simulated using an equivalent thermal loading from the analogy of thermal and autofrettage
residual stress fields. Thermal stresses due to the simulated thermal loadings for various degrees of autofrettage overstrain
level were computed using finite element methods. Very high stress concentration factors due to autofrettage loadings were
obtained at the external groove root that contained a sharp root radius. Experimental measurement of residual stresses for
a fully autofrettaged smooth thick-walled pressure vessel using an equivalent saw cut method resulted in very close agreement
with the theoretical autofrettage residual stress distributions. The stress analysis results implied that the autofrettage
residual stress concentration might cause a cracking problem at the external groove root of the thick-walled pressure vessel,
indicating that lower autofrettage overstrain and a groove geometry change were desirable for enhanced durability. 相似文献
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Qiu-Ming Yang Young-Shin Lee Eun-Yup Lee Jae-Hoon Kim Ki-Up Cha Suk-Kyun Hong 《Journal of Mechanical Science and Technology》2009,23(11):2913-2920
A program for the residual stress analysis of an autofrettaged compound cylinder is designed using a Matlab graphical user
interface (GUI) and program design technique. The high-pressure vessels are autofrettaged in order to increase their operating
pressure and fatigue life. An autofrettage process causes plastic expansion of the inner section of the cylinder, adding residual
compressive stress to the bore after relaxation. Such a compound cylinder is produced via a shrink-fit procedure that incorporates
a monobloc tube that has previously undergone autofrettage. This paper presents a simple and visual tool to calculate the
residual stress and describe the distribution of residual stress for both the elastic-perfectly plastic model and the strain-hardening
model. 相似文献
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自增强是通过提高压力容器的残余应力来增强他们的承载能力和疲劳寿命。自增强复合圆筒可以承受比一个具有相同尺寸的单层圆筒更高的压力。引入了应变硬化模型,对自增强复合圆筒的残余应力进行了分析,并对其分布进行了预测。研究表明:复合圆筒内壁的切向残余应力和应力幅随着超应变度的增大而增大。缩套是提高压缩残余应力的一个非常有效的方法。 相似文献
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考虑渗碳、磨齿、喷丸等工艺产生的齿面残余应力,建立齿面接触应力与残余应力的复合应力场,提出一种螺旋锥齿轮接触疲劳裂纹萌生-扩展寿命计算方法。构建齿轮有限元接触分析模型,计算多轴交变接触应力场。考虑空间螺旋曲面残余应力分布的复杂性,将变曲率齿面离散为网状节点;测量各节点表面与次表面的残余应力,建立齿面残余应力场。基于Dang Van多轴疲劳准则,构建齿面裂纹萌生模型;计及残余应力与裂纹闭合效应,构建齿面裂纹扩展模型。计算复合应力场下齿轮接触疲劳寿命,研究残余应力对齿面裂纹萌生-扩展寿命的影响规律。结果发现:复杂齿面空间变曲率会影响喷丸等工艺产生的残余应力分布,中心区域的残余压应力高出齿面边缘区域约20%;复合应力场下齿面裂纹萌生位置与寿命主要取决于接触应力,残余应力会改变齿面节点平均应力进而影响疲劳寿命;齿面裂纹扩展寿命约占全寿命的10%,表征齿轮接触疲劳快速失效至迅速断裂。上述研究对于高性能齿轮传动的长寿命、高可靠性设计具有一定的参考价值。 相似文献
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Autofrettage process analysis of a compound cylinder based on the elastic-perfectly plastic and strain hardening stress-strain curve 总被引:1,自引:0,他引:1
Eun-Yup Lee Young-Shin Lee Qui-Ming Yang Jae-Hoon Kim Ki-Up Cha Suk-Kyun Hong 《Journal of Mechanical Science and Technology》2009,23(12):3153-3160
The autofrettage process enhances the carrying capacity and fatigue lifetime of pressure vessels by increasing their residual
stress. A compound cylinder was introduced in order to increase residual stress. An autofrettaged compound cylinder can resist
a higher pressure than a single cylinder having the same dimension. This residual stress can be measured through experimental
or calculation processes. In this study, residual stress analysis of an autofrettaged compound cylinder was conducted. The
elastic-perfectly plastic and strain hardening models were investigated. The residual stress distribution of the autofrettaged
compound cylinder with shrink fit tolerance was predicted. Shrink fit is a very efficient way to extend compressive residual
stress. The compressive residual stress of the strain-hardening model is smaller than that of the elastic-perfectly plastic
model because of the Bauschinger effect. The compressive residual stress of the strain hardening model decreased by up to
80% overstrain level. 相似文献
7.
压力容器焊缝咬边疲劳裂纹的启裂寿命 总被引:1,自引:0,他引:1
针对某企业空气球罐焊缝咬边在压力波动时的受力情况,首先建立带咬边结构的受力模型,利用西田正孝的图表方法和有限元法分别计算咬边引起的弹性应力集中系数,然后计算出咬边尖端的名义应力,进而利用小缺口启裂寿命经验估算式估算咬边的疲劳裂纹启裂寿命。再采用与实物等厚度、与真实咬边等尺寸的模拟试样,进行与实际结构等应力范围条件下的模拟疲劳试验。结果表明,试验寿命与根据经验估算式得到的估算寿命非常接近,从而为咬边疲劳裂纹启裂寿命研究提供了理论依据和试验数据。在考虑一定的安全系数后,对所分析的球罐给出的剩余总寿命为9年,至启裂的剩余寿命为6年。 相似文献
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基于大型通用有限元软件ANSYS,对发生疲劳断裂的超高压管式反应器的端部结构进行数值模拟,分析了其在过盈套合、自增强处理以及服役期间开停工循环载荷三种工况下的局部应力场.结果表明:三种工况下,端部结构在过盈套合边缘局部范围内均存在较高的轴向拉应力,且大于环向应力;局部轴向应力随套合过盈量和自增强压力的增加而增大;半径过盈量为0.05 mm时,开停工循环载荷下的局部轴向平均应力最大值可达86.71 MPa,轴向交变应力幅值最大值达到62.2 MPa,裂纹垂直于轴向扩展的推动力较大.模拟分析结果对端部结构失效破坏原因的分析及其设计改进有一定的指导意义. 相似文献
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Common rail pipe in a clean diesel vehicle plays a key role in supplying fuel from a rail to an injector of each cylinder connecting engine under a repeated internal pressure. For satisfying EU emission standards, fuel injection pressure is increased to be over 200 MPa, and it causes stress concentration at the outer surface of neck part with discontinuity and complexity of shape of the pipe. For preventing folding defects and for improving a fatigue life, integrated design of a heading process and an autofrettage process are required because the methods for reducing the stress concentration by using changing design, material and adding heat treatments cause considerable effects on performance and price of the pipe. In this study, the heading process for checking folding defects of pipe head is performed by FEA, and an autofrettage process is designed for improving a fatigue life by considering the stress concentration at the complex and discontinuous shape. The optimal autofrettage pressure is required not only to relieve the stress concentration but also to be not beyond the allowable internal pressure for the process safety. The allowable internal pressure for the autofrettage process is determined by using theoretical analysis and FEA, and the stress distributions through the autofrettage process are obtained by using the commercial software, ANSYS-Workbench. On the basis of the FEA results, the autofrettage pressure is optimized, and SEM (scanning electron microscope) and fatigue tests were performed for prototypes to validate analysis of the integrated process design (Heading process and the autofrettage process). 相似文献
11.
合理划分缺陷周围有限元网格,并计算裂纹位置、跨度、裂纹所处角度对管道应力分布的影响,确定后续研究中使用的裂纹位置,跨度和裂纹角度。以此为基础分析裂纹尺寸、管道内压力和管道外部水流绕流所产生的激振力对管道应力和疲劳寿命的影响。结果表明,水流作用下含轴向裂纹悬空管道,水流激振力对管道峰值应力和疲劳寿命影响最大。 相似文献
12.
Hadi Taghizadeh Tajbakhsh Navid Chakherlou Afshin Babaei Aghdam 《Journal of Mechanical Science and Technology》2013,27(5):1415-1425
To predict fatigue crack initiation and fatigue crack growth lives in cold expanded double shear lap joints a numerical method has been employed. The total estimated fatigue lives were compared with available experimental fatigue test results for plain hole and cold expanded hole specimens of Al 2024-T3 in double shear lap joints. Three-dimensional finite element simulations have been performed in order to obtain the created residual stresses field due to cold expansion and subsequent far field longitudinal loading in the double shear lap joint. The obtained stress and strain distributions from the finite element analyses were employed to predict stress concentration factors to calculate fatigue crack initiation and fatigue crack growth lives using AFGROW computer code. The predicted fatigue lives demonstrate that there is a good agreement between the proposed method and experimental fatigue test results. 相似文献
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着重分析了零构件由于微动磨损而造成的疲劳失效机制 ,说明了在这种微动疲劳模式下疲劳寿命的组成情况 ,用门槛值应力公式估算了当磨蚀坑根部萌生扩展性裂纹时蚀坑的临界深度尺寸 ,并分析了微动裂纹尖端的应力强度因子 ,得出了计算微动裂纹萌生尺寸的表达式 ,最后用上述方法计算了螺纹联接件的微动磨损寿命与裂纹萌生尺寸 ,用局部应力应变法计算了微动裂纹的萌生寿命 ,所得到的估测寿命与试验值相符 ,由此可见 ,该微动疲劳寿命的估测方法是合理的、有效的 相似文献
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泵阀箱材质自增强与疲劳强度研究 总被引:3,自引:0,他引:3
以内壁带“V”型缺口的厚壁圆环为对象,对两种高压泵阀箱常用钢43CrNi2MoVa、42CrMoA在自增强处理前后的疲劳寿命进行了理论分析与实验研究。首先用弹塑性有限元法计算了自增强后所形成的残余应力,发现自增强处理后在缺口根部所形成的残余应力有一最大值,有明显的残余应集中现象。 相似文献
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为了确定残余应力松弛和自增强处理压力对在役高压容器安全性能的影响,通过分析测试结果获得了残余应力的松弛规律,计算了在工作压力、残余应力作用下的当量等效应力沿壁厚分布情况,模拟计算出了不同的工作压力、自增强处理压力下的安全系数,推导出了最佳自增强处理压力。结果表明所研究的高压聚乙烯反应管在使用10年后,环向应力在近内壁区衰减最快,从-600MPa衰减到-333MPa,衰减率达45%;在弹性区衰减较小,残余应力峰值位置外移,但其峰值大小变化不大。对于自增强处理后的压力容器,在工作压力作用下,随着残余应力的松弛,内壁面当量等效应力增大,当量等效应力在弹塑性交界处最大,应该按此处的当量等效应力计算安全系数。依据示例聚乙烯反应管尺寸,模拟计算出在工作压力分别为180、280、380MPa时,经过自增强处理压力分别为606、677、743MPa的最佳自增强处理后,其安全系数比残余应力全部衰减为0时分别高16%、26%、37%。压力容器工作压力越大,经最佳自增强处理后安全系数增大得越多,但残余应力衰减对其安全影响越大。 相似文献
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超高强度钢十亿周疲劳研究 总被引:12,自引:4,他引:12
利用20kHz压电超声疲劳试验技术,对六种抗拉强度高于1500MPa的低合金钢进行测试。结果表明,这些材料并不存在传统规范中所谓的“疲劳极限”,它们在超过10^7,甚至10^9应力循环后仍然继续发生破坏,而且其S-N曲线表现出“阶梯”型特征。研究还发现,这些材料都存在一个分界应力幅值区间(或应力循环数区间,大约在10^6到10^7的平台内),裂纹萌生由试件表面向其内部转换。实验证明了十亿周级超高周疲劳裂纹由试件内部萌生的机理。 相似文献
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基于循环J积分的压力容器疲劳寿命预测的数值模拟 总被引:3,自引:0,他引:3
开发出一种基于三维弹塑性循环J积分( J)的压力容器疲劳寿命预测的数值模拟技术。对1台含内壁纵向表面裂纹的实物压力容器进行有限元数值模拟计算和试验测试,结果显示:初始椭圆形表面裂纹在疲劳扩展过程中形状逐渐趋圆并保持圆形继续扩展。裂纹疲劳扩展过程是一个非等速的扩展过程,扩展速度呈现越来越快的趋势。基于J的疲劳寿命预测的数值模拟结果较之基于应力强度因子幅K的结果具有更高的精度,满足工程要求。该技术对于在役含缺陷压力容器的疲劳寿命预测具有重要的应用价值。 相似文献
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A study on the fatigue life prediction of tire belt-layers using probabilistic method 总被引:1,自引:0,他引:1
Dongwoo Lee Seongrae Kim Kideug Sung Jongsang Park Taewon Lee Sunchul Huh 《Journal of Mechanical Science and Technology》2013,27(3):673-678
Tire belt separation failure is occurred by internal cracks generated in #1 and #2 belt layers and by its growth. And belt failure seriously affects tire endurance. Therefore, to improve the tire endurance, it is necessary to analyze tire crack growth behavior and predict fatigue life. Generally, the prediction of tire endurance is performed by the experimental method using tire test machine. But it takes much cost and time to perform experiment. In this paper, to predict tire fatigue life, we applied deterministic fracture mechanics approach, based on finite element analysis. Also, probabilistic analysis method based on statistics using Monte Carlo simulation is presented. Above mentioned two methods include a global-local finite element analysis to provide the detail necessary to model explicitly an internal crack and calculate the J-integral for tire life prediction. 相似文献