共查询到18条相似文献,搜索用时 171 毫秒
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在实验室内对自增强厚壁管的残余应力衰减规律进行了一系列模拟强化实验 ,在总结试验结果的基础上用单因素叠加理论得出工程实用的残余应力衰减率的计算式[1] 。该计算式虽然得到一个工程实例的验证 ,这是不够的 ,还应经足够数量的工程实例的检验。然而 ,对昂贵的反应管进行破损检验是不现实的 ,这必然要求找到一种能够对高压聚乙烯反应管内壁残余应力进行无损检测的有效方法。另外 ,反应器内壁残余应力的大小可作为反应器安全的一个重要指标来加以检验。因此 ,研究反应管内壁残余应力无损测量方法是十分必要的。到目前为止 ,国内还没有自增… 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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某新型反应堆压力容器内壁设计了环形锻件与筒体内壁焊接的环形焊接结构。该种结构形式的焊缝首次在反应堆压力容器中出现,无成熟经验可以借鉴。为了了解该种复杂结构形式及大厚度焊缝的焊接残余应力幅值及分布规律,基于ANSYS有限元分析软件,建立了反应堆压力容器内壁环形锻件多层多道焊接三维有限元模型。在此基础上,以带状移动温度热源作为焊接热源模型计算出多层多道焊接的瞬态温度场结果,采用热-力间接耦合法,得到了焊接应力场计算结果。模拟结果表明,焊缝区域环向应力从上表面到下表面分布趋势为拉应力-压应力-拉应力,呈现自平衡的分布形式。根部焊道区域的环向应力为拉应力。焊缝上轴向应力最大为300 MPa左右;焊缝上下表面径向应力较大,达到400~500 MPa左右;峰值等效应力出现在焊缝根部区域,幅值最大约700 MPa。 相似文献
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基于三剪统一强度准则,考虑材料应变强化效应、包辛格效应、拉压异性及中间主应力的影响,采用双线性强化材料模型对厚壁圆筒进行自增强分析,得到了厚壁圆筒加载应力、残余应力和工作应力的解析解,提出了最佳自增强压力的计算方法,探讨了拉压比、强度准则变化参数的影响,比较了自增强处理和非自增强处理及双线性强化模型和理想弹塑性模型厚壁圆筒的应力分布差异。研究结果表明:厚壁圆筒的最佳自增强压力随半径比和强度准则参数的增大而增大;工作时的最大等效应力随半径比和强度理论参数的增大而减小,随拉压比的增大而增大;自增强等效应力的最大值在弹塑性分界面处,且应力沿壁厚的分布较均匀;与理想弹塑性模型相比,双线性强化模型所对应的弹塑性分界面半径和残余应力较小,且随着自增强压力的增大,两种模型的差值越来越大;等效应力随半径比的变化规律可为厚壁圆筒选择合理的壁厚提供一定的参考;自增强技术可改善厚壁圆筒工作时的实际应力分布,提高其极限承载能力。 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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1 简介为提高高压圆筒的承载能力和疲劳强度,常采用自增强处理工艺,使简体内壁产生残余压应力。残余应力的无损检测方法有X射线法、磁测法、超声法等。X射线法和磁测法只能测定试件表面一薄层材料的残余应力,超声法也只能测定简单应力状态的构件(如螺栓的轴向拉力),而对于象厚壁圆筒经自增强处理后的残余应力,用该法测定十分困难。残余应力的 相似文献
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为了提高超高压聚乙烯管式反应器的弹性操作范围和抗疲劳能力,该反应管在制造时进行了自增强处理,但由此而产生的残余应力会随着长期使用而有所衰减。为了分析残余应力衰减对该反应管安全性的影响,合肥通用机械 相似文献
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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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Seung-Kee Koh 《Journal of Mechanical Science and Technology》2000,14(9):935-946
Elastic-plastic stress analysis has been performed to evaluate the fatigue life of an autofrettaged pressure vessel containing cross-bores subjected to pulsating internal pressure of 200 MPa. Finite element analyses were used to calculate the residual and operating stress distributions of the pressure vessel due to the autofrettage process and pulsating internal pressure, respectively. Theoretical stress concentration factors of 3.06, 2.58, and 2.64 were obtained at the cross-bore of the pressure vessel due to internal pressure, 50%, and 100% autofrettage loadings, respectively. Local stresses and local strains determined from the elastic-plastic finite element analysis were employed to calculate the failure location and fatigue life of the pressure vessel with radial cross-bores, incorporating the low-cycle fatigue properties of the pressure vessel steel and fatigue damage parameters. Increase in the amount of overstrain by autofrettage process moved the crack initiation location from the inner radius toward a mid-wall, and extended the crack initiation life, Predicted fatigue life of the fully autofrettaged pressure vessel with cross-bores increased about 50%, compared to the unautofrettaged pressure vessel. At the autofrettage level higher than 50%, the failure location and fatigue life of the pressure vessel were not significantly influenced by the autofrettage level. 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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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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基于失效评定图技术理论,根据贮氢压力系统结构、材料和载荷特点,制定结构安全评定程序及项目。缺陷检测结果表明:贮氢压力系统主缺陷为焊缝底端未焊透。将其表征为三参量矩形环向缺口,结合材料性能数据,通过有限元应力求解可知:离心及内压综合载荷作用下最大等效应力出现在未焊透根部两侧尖端,随缺陷深度增加而增大,且变化趋势基本成线性关系;随宽度减小而增加,但宽度值大于0.5 mm后,最大等效应力基本不再变化。计算贮氢前后不同深度缺陷失效评定点Lr和Kr值,绘于失效评定图中,评定结论如下:当未焊透缺陷深度不超过60%壁厚时,结构是安全的,安全系数大于1.5;结构失效模式为塑性失稳,长期贮氢后由于材料断裂韧度的下降及缺陷的扩展,失效模式将逐步由塑性失稳转为弹塑性断裂,但效应并不显著。 相似文献