Containment of explosions in cylindrical shells

An experimental and theoretical investigation of the high explosive containment ability of circular cylindrical shells is presented. Approximate expressions for final circumferential strain or radial displacement as a function of cylinder length are developed in terms of elementary functions, based upon an assumed rigid-plastic material relation for the containment vessel. The material relation includes strain hardening and approximate strain-rate sensitivity. The expressions are presented in a form convenient for containment design purposes and are shown to be in reasonable agreement with experimental results for several container materials and radius-to-thickness ratios.     

航空发动机涡轮叶片包容模拟试验研究

为消除航空发动机非包容失效,首先需要通过叶片包容试验了解发动机部件的撞击、变形和破裂过程。在高速旋转试验台上进行模型的叶片包容试验,使用高速相机和高速数据采集系统构建特别的触发系统,记录叶片撞击机匣时的转子转速、机匣外壁上的应变波及叶片的运动轨迹。试验结果表明,叶片长度和动能对部件的撞击变形及破坏结果有极大的影响。高能量长叶片撞击将引起大变形,叶片弯曲成U形,机匣在第二次撞击处被撕裂击穿。相反地,叶片较短时,即使具有较高的撞击能量,对机匣的破坏作用也是极小的。叶片包容试验可以为结构优化设计和叶片包容仿真软件的开发提供大量有价值的数据。     

充砂爆炸容器动态响应的试验研究

通过试验研究了爆炸容器在充砂和空气两种环境下的动态响应规律,分析了填砂厚度、装药量对容器动态响应影响的机制,根据试验结果从装药密度、装药比例距离、容器壁厚与药径比三个方面分别提出了有利容器力学安全的临界值。试验结果表明：对与文中几何相似的钢质爆炸容器来说,当装药比例距离大于0．40m／kg^1/3。左右时,容器内填砂对其力学安全有利,即填砂情况下容器的环向应变峰值较大气环境下显著降低;从装药密度来说,当装药密度小于2．05kg／m^3时,容器内填砂对其力学安全有利;从容器厚度与药柱半径之比δ／RTNT,来说,当δ／RTNT值大于0．70时,容器内填砂对其力学安全有利。     

A method of prediction of the phase change front

Solidification on the outside wall of a convectively cooled tube is investigated. Experiments on solidification of an initially stagnant liquid onto a convectively cooled vertical tube situated concentrically within the containment vessel are carried out. The transient temperatures of the tube at various axial locations are obtained as a function of time. Using these data for the wall temperatures, the transient position of the phase change front is predicted by the optimization technique proposed in Choi, H.O. and Chun, M.H. (1985). Transient shapes of the solid-liquid interface are photographically recorded at pre-selected times in order to compare with the preditions of the optimization technique. The natural convection flow due to the temperature variations developed in the liquid phase has shown a drastic influence on the freezing process and the shape of the frozen-layer.     

AP1000主蒸汽管道镗孔壁厚设计分析

AP1000主蒸汽管道与蒸汽发生器连接。根据设计要求,主蒸汽管道与蒸汽发生器管嘴连接的焊缝需要进行役前和在役检查,同时位于安全壳内的主蒸汽管道需要满足先漏后破原则。为了满足上述设计和运行要求,主蒸汽管道需要进行镗孔加工并且满足镗孔后的最小壁厚要求。通过分析设计给出的主蒸汽管道外径及公差和蒸汽发生器管嘴内径及公差要求,发现主蒸汽管道镗孔后其壁厚可能无法满足设计要求,从而判断设计要求自身耦合出现偏差,建议修正主蒸汽管道外径公差值。     

A new x-ray interface and surface scattering environmental cell design for in situ studies of radioactive and atmosphere-sensitive samples

We present a novel design of a purpose-built, portable sample cell for in situ x-ray scattering experiments of radioactive or atmosphere sensitive samples. The cell has a modular design that includes two independent layers of containment that are used simultaneously to isolate the sensitive samples. Both layers of containment can be flushed with an inert gas, thus serving a double purpose as containment of radiological material (either as a solid sample or as a liquid phase) and in separating reactive samples from the ambient atmosphere. A remote controlled solution flow system is integrated into the containment system that allows sorption experiments to be performed on the diffractometer. The cell's design is discussed in detail and we demonstrate the cell's performance by presenting first results of crystal truncation rod measurements. The results were obtained from muscovite mica single crystals reacted with 1 mM solutions of Th(IV) with 0.1 M NaCl background electrolyte. Data were obtained in specular as well as off-specular geometry.     

Simulation of wall film condensation with non-condensable gases using wall function approach in component thermal hydraulic analysis code CUPID

In the containment of nuclear power plants, wall film condensation occurs with non-condensable gases under accident conditions. With non-condensable gases, condensation heat transfer on the containment wall can be degraded significantly because of the accumulation of non-condensable gases near the condenser wall; therefore, an investigation into the wall condensation heat transfer is of great importance to nuclear reactor safety. In this study, wall film condensation with non-condensable gases was simulated using the CUPID code. To evaluate the heat and mass transfer coefficients, a wall function approach was adopted to save the computational cost. To validate the model, a COPAIN condensation experiment was simulated using CUPID. The calculation results were compared with the COPAIN experiment data and results from the commercial CFD code (STAR-CCM+) results, which used the resolved boundary layer approach. From the comparison, good agreements were obtained between the CUPID code and the other results.     

钢管混凝土构件的爆炸荷载试验研究

针对钢管混凝土结构构件在爆炸冲击荷载作用下的动力响应进行研究,试验对象为相同管径三种不同壁厚的钢管混凝土结构构件在简支状态下,受到两种不同爆炸冲击荷载的作用,测量了两种不同爆炸空气冲击波的压力时间曲线、构件跨中的应变时间曲线和构件跨中的最终挠度值,并对测量结果进行分析,为钢管混凝土构件的抗爆炸荷载设计提供有益的试验成果,也为后续进一步研究提供有效的基础数据和可靠的对比参照.     

Distributed model reference adaptive containment control of heterogeneous uncertain multi-agent systems

In this paper, a distributed model reference adaptive control (MRAC) design framework is proposed for containment control of heterogeneous uncertain multi-agent systems (MAS). Both groups of leaders and followers are considered to have general linear dynamics with the leaders subject to bounded external inputs and the followers subject to uncertain system dynamics. Two distributed adaptive control protocols are developed under this framework. The first protocol assumes measurable leaders’ input signals for a subset of the followers, and employs distributed observers with state-feedback adaptive controllers to achieve exact containment control performance. The second protocol incorporates robust adaptive control with nonlinear compensator techniques to handle a more challenging scenario of unmeasurable bounded leaders’ inputs. Convergence of the containment control errors to an arbitrarily adjustable neighborhood of the origin is guaranteed with the second protocol. The proposed MRAC framework provides a promising alternative solution over the prevailing cooperative output regulation framework for heterogeneous linear MAS containment control. It enables us to handle more general system settings under more stringent control environments with limited accessibility of leaders’ information and uncertain follower dynamics. Effectiveness and usefulness of the proposed approaches are demonstrated through extensive simulation studies, including an application to containment control of multiple nonholonomic mobile robots.     

Computational study of the mixed cooling effects on the in-vessel retention of a molten pool in a nuclear reactor

The retention of a molten pool vessel cooled by internal vessel reflooding and/or external vessel reactor cavity flooding has been considered as one of severe accident management strategies. The present numerical study investigates the effect of both internal and external vessel mixed cooling on an internally heated molten pool. The molten pool is confined in a hemispherical vessel with reference to the thermal behavior of the vessel wall. In this study, our numerical model used a scaled-down reactor vessel of a KSNP (Korea Standard Nuclear Power) reactor design of 1000 MWe (a Pressurized Water Reactor with a large and dry containment). Well-known temperature-dependent boiling heat transfer curves are applied to the internal and external vessel cooling boundaries. Radiative heat transfer has been considered in the case of dry internal vessel boundary condition. Computational results show that the external cooling vessel boundary conditions have better effectiveness than internal vessel cooling in the retention of the melt pool vessel failure.     

国产S30408奥氏体不锈钢应变强化低温容器许用应力及应变确定

对奥氏体不锈钢低温压力容器常规设计与应变强化设计进行比较,可知应变强化技术可大幅提高奥氏体不锈钢材料的许用应力,减薄简体壁厚,减轻容器重量。根据预应变拉伸试验确定国产S30408奥氏体不锈钢应变强化压力容器的应变上限值,并建立国产S30408奥氏体不锈钢材料的ASME和双线性这两种应力应变曲线,对两者进行比较后,以ASME应力应变曲线为计算依据,考虑抗拉强度的影响,确定了国产S30408奥氏体不锈钢材料制造应变强化低温容器时的许用应力及其对应的应变。     

海洋环境下浮动堆设备闸门密封性能分析

浮动堆长期处于海洋环境中,其安全壳设备闸门处于海洋环境下浮动堆的随机运动状态中,同时外部的冲击事故也会对其结构造成严重破坏,由设备闸门与安全壳一起形成第三层屏蔽,包容放射性物质,是安全壳压力边界的重要组成部分,也是安全壳压力边界较薄弱的环节,因此设备闸门密封性能对于浮动堆的核安全至关重要。结合水动力学和瞬态动力学,分析事故工况下设备闸门密封面上下法兰的变形,提取最大变形处相对位移值,构建二维密封面模型模拟事故工况下密封面变形情况,并基于二参数的Mooney-Rivlin本构模型描述密封圈材料的应变能函数,分析密封圈总体变形、应力分布、接触应力分布,结合试验数据判定海洋环境下浮动堆设备闸门事故工况下密封性能分析。     

80gTNT当量爆炸容器的研制

以现行的压力容器国家和行业标准为依据,结合爆炸强动态载荷瞬间作用的特殊性,运用动力系数法设计了一个可以重复使用的柱形爆炸容器。实验结果证明,该容器设计合理,工作安全可靠。     

多头等壁厚橡胶螺杆钻具定子有限元分析

利用三维设计软件,建立了常规螺杆钻具定子和等壁厚橡胶螺杆钻具定子的二维平面模型,在有限元分析软件环境下,进一步建立定子的有限元分析模型,并分析了定子橡胶衬套内表面在均匀压力作用下的应力、应变和位移的分布规律。结果表明,在相同压力下,等壁厚衬套比常规衬套有更好的抗形变能力;在相同的过盈量下,等壁厚衬套有更好的密封能力;在同等扭矩下,等壁厚定子的长度可以缩短,等壁厚橡胶衬套内表面相对位移变化小,使转子与定子间产生均匀的过盈,从而提高了螺杆钻具的工作性能。     

Interaction of bifidobacteria with the gut and their influence in the immune function

Bifidobacteria are predominant in the lumen of the large intestine and confer various health benefits on the host. They are also used in the preparation of new fermented milks (bioyogurts) or added to conventional yogurt to generate probiotic effects. The colonization of the gut by bacteria tends to be host specific due partly to the way in which bacteria adhere to the intestinal wall. Using a homologous strain of Bifidobacterium animalis in an experimental mouse model, we analyzed by immunofluorescence labelledbacteria and transmission electronic microscopy the importance of this bacterial interaction with epithelial an immune cells associated to the gut, and the effect of feeding of B. animalis in the immune response. It was able to adhere and interact with both small and large intestine. In spite of this interaction with the gut, no modifications in the immune state (secretory or systemic response) were observed.
A heterologous strain of Bifidobacterium adolescentis from human faeces, was neither uncapable of binding to the intestine, nor influence the immune system activation, when it was administered during 2, 5 or 7 consecutive days; we believe that using a homologous strain, oral tolerance is developed even when the microorganism interacts with the immune cells associated with the intestine. However, we cannot ignore the beneficial effect of these microorganisms, especially in the prevention of intestinal infections. We think that this property exerted by bifidobacteria is more related to other mechanisms such as competitive inhibition, acid production or others, than enhancement of the immune state.     

基于响应面法的高温高压染色机筒体壁厚优化设计

使用响应面法取代高精度工程模拟可以减少设计周期和成本,同时是解决复杂结构优化设计的有效途径。将有限元法和响应面法相结合,建立了染色机筒体壁厚与高温高压染色机最大主应力的函数表达式;并以染色机质量最轻为目标函数,对染色机筒体壁厚进行了优化设计;最后通过有限元仿真对优化结构进行了验证。优化后染色机的质量减轻了0.061 t,并且满足应力要求。结果表明,基于响应面法的染色机筒体壁厚优化设计具有很好的应用价值。     

Elevated temperature design evaluations for the ABTR internal structure

The preliminary structural analyses for an advanced burner test reactor (ABTR) internal structure are performed with regard to the elevated temperature design and the seismic design. In the elevated temperature design, three load cases enveloped from ABTR duty cycle events are studied for the structural integrity evaluation according to the ASME-NH design rule. The resulting stresses and strains are compared with the allowable design and service limits. An elastic approach, a simplified inelastic approach and a creep fatigue analysis are performed to provide a quantitative assessment of the deformations and strains. In the seismic design, the response spectrum analyses including the fluid-structure interaction effect are performed for isolated and non-isolated conditions. From the evaluation results, it is found that the seismic isolation capable of reducing the seismic input transmitted to the foundations is needed to satisfy the allowable design limits. For the isolated condition, three design cases for the variation of the wall thickness as 1.5 cm, 2 cm and 3 cm are studied for the design modification.     

某迫击炮身管结构优化分析

考虑采用新型工艺后材料最大弹性极限,研究了某迫击炮身管壁厚减薄的结构优化方法。首先,采用有限元方法进行静态分析,通过三维软件 UG建立了身管实体模型。对身管结构进行合理简化后,导入到 ANSYS中进行膛压分析计算,得到了身管不同位置管壁所受应力随壁厚减薄的变化曲线。综合分析各种壁厚减薄方案,得到了身管承载性能最优的方案,并采用流固耦合动态响应加以验证。结果表明,静态分析结果较动态分析结果更接近真实受力状况。最终,迫击炮身管结构重量经仿真优化后可减轻13%,因而,该身管轻量化方法有效而可靠。     

Improving profile accuracy in SPIF process through statistical optimization of forming parameters

In single-point incremental forming (SPIF) process, a number of parameters are involved and need to be adjusted before the commencement of the forming operation. The inappropriate selection of these parameters could be detrimental to process accuracy. In this paper, the effect of five parameters, namely, sheet thickness, tool radius, step size, wall angle, and pre-straining level of sheet, on the profile accuracy of the produced part of AA1060 with SPIF is experimentally investigated. A response surface method is employed for the experimental design and regression analysis. The experimental results are presented in the form of graphical three-dimensional response surfaces. The results of ANOVA show that the sheet thickness, wall angle, step size, and the interaction between the sheet thickness and wall angle are extremely significant in terms of their effect on profile accuracy. Furthermore, an empirical model is proposed to achieve improved profile accuracy in terms of the optimized parameters.     

国际高强度管线钢管的研究进展

介绍了高强度大壁厚管线钢管、基于应变设计的管线钢管以及酸性服役钢管的最新发展及应用。X80级管线钢管已经应用于北美及中国的天然气长输管线。高强度、大壁厚、优良的低温韧性、抗大变形性能及耐酸性等特殊性能为当前管线钢管的发展趋势。欧洲、北美及日本等钢铁企业在全尺寸试验等基础研究及高性能钢管的开发上处于领先地位。