共查询到20条相似文献,搜索用时 187 毫秒
1.
采用有限元分析法和试验测定法,对内压与弯矩联合作用下外拱局部减薄弯管的极限载荷进行了研究。有限元计算结果及试验结果表明,不同的局部减薄,弯管的极限弯矩随内压变化规律不同;当缺陷尺寸参数α/b〉0.313时,极限弯矩随着内压的增加先增加后减小;当α/b≤0.313时,极限弯矩随内压的增加而减小。通过拟合有限元计算结果,得到了内压与平面闭合弯矩联合作用下外拱局部减薄弯管的安全评定方法。 相似文献
2.
对环形窄缝通道内单相水在双面处于不同的加热热流密度情况下的对流换热特性进行了数值计算.计算结果表明,环形通道内、外壁加热热流密度比值的不同,对环形通道内、外壁与单相水的对流换热特性有着显著的影响.内、外壁面加热热流密度比值较小时,内壁的换热强于外壁的换热,随着内壁加热热流密度的增大,外壁的换热得到增强.但是,当内、外壁加热热流密度比值增加到一定程度时,外壁的对流换热特性将超过内壁的对流换热特性,与文献报道的实验结果一致.此外,环缝间隙的减小将导致环形通道的换热性能下降. 相似文献
3.
4.
5.
秦山核电二期工程反应堆压力容器、稳压器出厂水压试验应变测试 总被引:1,自引:0,他引:1
根据测试的环境不同,选取不同性能的应变片.容器外壁为空气环境,选取普通的应变片;容器内壁为高压水环境,选取适合高压水下环境测试的应变片.根据测试的应变数据绘制相应的曲线,计算相应的应力强度;同时,建立有限元计算模型,从理论上计算出测试点的应力强度,使之与应变测试得到的应力强度进行比较,并对比较结果进行分析. 相似文献
6.
7.
8.
采用流-固耦合的方法,利用计算流体力学程序(CFX)软件,对方环管内超临界水传热特性进行数值模拟研究,得到方环管内加热管的温度分布,并对加热管温度分布的周向不均匀性进行分析评价.计算结果表明,方环管内加热管的外壁面温度的周向不均匀性高于内壁面,内壁面的温度周向不均匀性非常低,壁面周向平均温度满足一维导热公式.窄通道与角通道处流体先后通过拟临界区域,促使加热管外壁面温度的周向不均匀性随主流体比焓值的增加出现3个不同变化特征的区域.等壁面热流密度条件下,计算结果与等体积释热率条件有较大程度的不同.等体积释热率的假设与实际情况更加接近,说明实际情况下固体内部存在周向导热,促使周向温度分布更加均匀. 相似文献
9.
本文对LOCA工况长期稳定阶段安全壳非能动冷却系统的冷却能力进行分析计算。研究了安全壳外壁面与空气折流板之间内环廊的特性与参数。在假设安全壳内壁面温度的前提下,分析计算涉及的各传热过程,相关的安全壳外壁面冷却水膜蒸发量与未蒸发水温选用特定值。通过安全壳外壁面向内环廊空气散热量的两个相关等式形成闭环,进而修正假设的安全壳内壁面温度并重新迭代计算。计算结果表明,安全壳冷却导出热量为6.99 MW,而相应阶段安全壳内事故释放热量为6 MW,即对应本文分析的具体情况,安全壳非能动冷却设计是有效的。 相似文献
10.
预应力损失对安全壳在内压作用下的安全性能影响不可忽略,本文通过考虑安全壳不同龄期下的预应力损失来研究安全壳在设计基准期内40年及设计基准期后60年不同内压水平作用下的安全性能。采用ABAQUS有限元软件建立了精细化安全壳三维有限元分析模型,通过非线性有限元方法分析了钢衬里屈服、预应力筋屈服、混凝土裂缝演化等性能指标。研究结果表明,考虑预应力损失后,安全壳混凝土开裂与钢衬里失效时,所能承受的内压荷载减小;安全壳在极限内压作用下的变形表现为穹顶向外膨胀以及洞口向内收缩;安全壳穹顶部分在极限内压下破坏严重;考虑预应力损失后,安全壳变形明显增大。但安全壳在设计内压(0.4 MPa)作用下仍有足够的安全裕度。 相似文献
11.
The objective of this study is to validate a finite element analysis (FEA) simulation methodology to predict the out-of-plane behavior of piping elbows. Two out-of-plane elbow experiments and the corresponding FEA shell and elbow element models are presented. For load–displacements results, all the FEA predictions showed excellent agreement with measured experimental results, and for load–strain behavior, the shell FEA model results correlated quite well with the experimental results. 相似文献
12.
Young-Shin Lee Chung-Hyun Ryu Hyun-Soo Kim Young-Jin Choi 《Nuclear Engineering and Design》2005,235(20):546-2226
The package used to transport radioactive materials, which is called a cask, must be designed to keep its contents safe under normal and hypothetical accident conditions. The design requirements of the cask are verified by test or finite element analysis (FEA). Comparing evaluation procedures for the safety of a new cask, the cost of FEA is generally much less than that test. Therefore, FEA is mainly used to verify safety of a cask under the considered conditions. However, one commercial FEA code may show different results from another FEA code for the same problem due to the modeler's several assumptions for simplifying actual states into the FE model and due to modeling technique. Materials of the components of a cask display elastic–plastic or elastic–perfectly plastic behavior under the considered conditions in which large deformation, impact and contact mechanism are included. The behavior is simulated with difficulty and may have different results depending on FEA codes. In this paper, finite element analysis is carried out for the 9-m free drop and the puncture condition under the hypothetical accident condition by using LS-DYNA3D and ABAQUS/Explicit. Energy and effective stress on each component are presented and compared between the two FEA codes, where the effective stress designates the maximum von Mises stress on inner and outer shells. 相似文献
13.
The objective of this study is to validate a finite element analysis (FEA) simulation methodology to predict the global behavior of thin-walled elbows subjected to in-plane bending. Two in-plane closing mode bending tests and one in-plane opening mode bending test were conducted on 2″ schedule 10 elbows, and a nonlinear FEA procedure was used to simulate the tests. A detailed FEA study was carried out to determine the relative importance of weld size and location, measured wall thicknesses, and original cross-section dimensions on the reconciliation results. When the weld bead was included in the analysis, the reconciliation results for load–displacement behavior and some of the strain measurements were excellent. For those cases in which the strain measurements reconciliations were not so good, a possible explanation is provided. 相似文献
14.
《Fusion Engineering and Design》2014,89(7-8):985-990
The divertor is one of the most challenging components of “DEMO” the next step ITER machine, so many tasks regarding modeling and experiments have been made in the past years to assess manufacturing processes, materials and thus the life-time of the components. In this context the finite element analysis (FEA) allows designers to explore multiple design options, to reduce physical prototypes and to optimize design performance.The comparison between the hydraulic thermal-mechanical analysis performed by ANSYS WORKBENCH 14.5 and the test results [1] on small-scale mock-ups manufactured with the Hot Radial Pressing (HRP) [2] technology is presented in this paper.During the thermal fatigue testing in the Efremov TSEFEY facility to assess the heat flux load-carrying capability of the mock-ups, only the surface temperature was measured, so the FEA was important because it allowed to know any other information (temperature inside the materials, local water temperature, local stress, etc.). FEA was performed coupling the thermal-hydraulic analysis, that calculated the temperature distributions on the components and the heat transfer coefficient (HTC) between water and heat sink tube, with the mechanical analysis.The comparison between analysis and testing results was based on the temperature maps of the loaded surface and on number of the cycles supported during the testing and those predicted by the mechanical analysis using the experimental fatigue curves for CuCrZr-IG, that is the structural material in the component. Also the behavior for Cu-OFHC interlayer material based on the experimental fatigue curves was considered and the ultimate tensile strength for W, because their failure affects the heat removal capability of the component.The good correlation found between FEA results and testing campaign validated again the use of FEA itself for future design improved concepts. 相似文献
15.
Acrylic acid (AAc) and styrene (St) were grafted onto poly(vinylidene fluoride) (PVDF) powder or membrane samples by pre-irradiation graft copolymerization.The grafted chains were proved by FT-IR spectroscopy analysis.The degree of grafting (DG) of the grafted PVDF was determined by fluorine elemental analysis (FEA) method,and was compared with the DGs determined by weighing method,acid-base back titration method and quantitative FT-IR method.The results show that the FEA method is accurate,convenient and universal,especially for the grafted polymer powders. 相似文献
16.
Alaa Mohamed Maurice Lemaire Jean-Claude Mitteau Eric Meister 《Nuclear Engineering and Design》1998,185(2-3)
Nuclear engineering systems are designed to ensure safety criteria. To predict the behavior of mechanical systems, the finite element analysis (FEA) is actually the main tool for numerical analysis of mechanical problems. In order to design a system under data variability considerations, performance functions have to be defined by the relationship between the action effects and the material strengths. Then a certain level of safety should be satisfied with sufficiently high probability. This is the subject of the reliability theory. Controlling a FEA software in order to carry out the reliability analysis, it is to define a ‘combination method’. This paper proposes a general method for the reliability analysis combined with FEA codes. The method is efficient for independent, correlated and compound random variables. The proposed method is illustrated by numerical example of a cracked membrane exposed to thermal shortening. The risk to evaluate is represented by the crack propagation in the material. 相似文献
17.
18.
19.
20.
Dynamic contact impact from hydraulic flow-induced fuel assembly vibration is the source for grid-to-rod fretting in a pressurized water nuclear reactor (PWR). To support grid-to-rod fretting wear mitigation research, finite element analysis (FEA) was used to evaluate the hydraulic flow-induced impact intensity between the fuel rods and the spacer grids. Three-dimensional FEA models, with detailed geometries of the dimple and spring of the actual spacer grids along with fuel rods, were developed for flow impact simulation. The grid-to-rod dynamic impact simulation provided insights of the contact phenomena at grid-rod interface. It is an essential and effective way to evaluate contact forces and provide guidance for simulative bench fretting-impact tests. 相似文献