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在核电站设计中,地震是需要考虑的基准载荷,需要评估地震载荷产生的动态响应,以确保核电站物项(系统、结构及部件)的完整性。目前,国内外抗震设计的计算机仿真软件门类众多,功能各有侧重,但对地震载荷的计算方法主要有静力法、反应谱分析法和时程分析法。以管道有限元计算软件PIPESTRESS为工具,研究PIPESTRESS软件动力分析方法的理论公式;介绍反应谱分析法、通用响应分析法及真时程分析法3种分析方法的特点;总结3种分析方法的实现命令流和求解设置。以某核电站主蒸汽管道为例,对地震响应分别采用反应谱分析法、通用响应分析法及真时程分析法进行计算,并将计算结果进行对比分析,分析3种方法的保守性,为管道抗震计算方法的选取提供参考。 相似文献
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针对并联摇摆台的支撑特点,采用节点载荷分配系数的方法将动平台的交叉梁系拆分为简支梁,根据同一节点处变形量相等的条件,建立关于各节点载荷分配系数的方程,进而计算出交叉梁系的最大变形量。分别计算交叉梁系在非冗余和冗余驱动时的最大变形量,并采用有限元的方法对其进行验证,表明节点载荷分配系数法计算交叉梁系的变形量是合理的。当机构存在驱动误差时,动平台可以通过自身刚度的变化减小由于误差而产生的系统内力。 相似文献
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采用有限元技术,应用ANSYS仿真软件分析复合材料结构弹翼在单位载荷矩阵作用下的结构响应,通过建立计算模型,施加边界条件及多步载荷并进行求解,得到复材弹翼结构的位移情况,提取计算模型的节点位移值形成弹翼的柔度系数矩阵,该种计算方法能够充分考虑到复合材料结构特性为气动吹风试验设计与气动外形研究提供可靠的结构数据。实现了气动与结构的联动设计同步更新。 相似文献
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Vibration has severely increased at the branch pipe of the main steam header since the beginning of commercial operation of
nuclear power plants. Intense broadband disturbance flow at a discontinuous region such as elbows, valves or headers generates
an acoustical pulsation which is propagated through the piping system. The pulsation becomes the source of low frequency vibration
at the piping system. If it coincides with the natural frequency of the pipe system, excessive vibration results. High-level
vibration due to the pressure pulsation related to high dynamic stress, and ultimately, to failure probability fatally affects
the reliability and confidence of the plant piping system. This paper discusses steady-state high vibrations appearing in
the branch piping system due to the effect of acoustical pulsations transmitted from the large main steam header by broadband
turbulence in a 700 MW power plant. The excitation sources and response of the piping system are investigated by using on-site
measurements and analytical approaches. Energy absorbing restraints with additional stiffness and damping factor were designed
and installed to reduce vibration damage. 相似文献
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《Measurement》2015
There have been many reports of fatigue failures of small-bore piping systems such as drain piping, vent piping and instrumentation piping in nuclear power plants that arise from vibration sources such as pumps. To prevent the failures, integrity evaluation of piping is conducted by measuring and analyzing vibration stress in the piping. But, a more efficient and economical measurement method is desirable to evaluate the vibration fatigue in small-bore piping. In this study, a non-contacting measurement method was proposed that is based on optical displacement sensors using light emission diodes (LEDs) to measure the vibration stress. The applicability of the method was discussed based on the vibration experiments using pipe elements and a mock-up piping system. From the experimental results, the proposed method was clarified to be sufficiently applicable and practically useful for the vibration measurement and stress evaluation in small-bore piping systems. 相似文献
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为了分析功率二分支齿轮传动系统的动力学特性,构建由斜齿分扭传动级与人字齿并车传动级构成的分扭 并车纯扭转动力学模型;通过高斯消元去除状态方程中的冗余变量,解决了系统动力学方程的奇异性并采用 4 阶 Runge-Kutta 法数值求解;分析了无量纲时间下不同齿型构成的 2 级传动动载特性,采用模态分析法,确定该系统的固有频率与固有振型,并结合三维瀑布图分析激振频率对系统共振特性的影响。研究结果表明:该齿轮传动系统由人字齿构成的并车传动级动力学特性优于由斜齿构成的分扭传动级;系统啮合位移与动态啮合力响应瀑布图表明,在该系统激振频率为 1820 Hz 时,系统出现超谐波共振。 相似文献
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基于管道振动的模态分析及谐响应分析,计算管道的声辐射效率,建立结构体振动与其辐射噪声之间的关系。文中首先建立管道的圆柱壳模型,进行管道结构动力学分析,采用有限元方法获得结构表面振动速度;然后根据结构声辐射理论,并且采用边界元法离散积分方程,通过建立管道的声场模型,得到管道结构在谐波激励下的声辐射效率,为降低噪声提供理论依据。计算结果表明,本文所建立的振动和声辐射模型及算法是有效的。 相似文献
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Doo Ho Cho Seung Wan Woo Yoon-Suk Chang Jae-Boong Choi Young-Jin Kim Myung Jo Jhung Young Hwan Choi 《Journal of Mechanical Science and Technology》2010,24(3):681-686
This paper is to report enhancement of engineering J estimation for semi-elliptical surface cracks under tensile load. Firstly, limitation of the sole solution suggested by Zahoor is shown for reliable structural integrity assessment of thin-walled nuclear pipes. An improved solution is then developed based on extensive 3D FE analyses employing deformation plasticity theory for typical nuclear piping materials. It takes over the structure of the existing solution but provides new tabulated plastic influence functions to cover a wide range of pipe geometry and crack shape. Furthermore, to facilitate easy prediction of the plastic influence function, an alternative simple equation is also developed by using a statistical response surface method. The proposed H 1 values can be used for elastic-plastic fracture analyses of thin-walled pipes with a circumferential surface crack subjected to tensile loading. 相似文献
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《流体机械》2016,(2):34-38
为了解决某装气站放空管线排气放空时引起的管路振动问题,建立流固耦合三维动力有限元模型,采用瞬态时间历程分析方法对放空管道进行冲击气流下管道动力响应仿真分析。其中管道内流体分别选择氮气和液化气,建立现有管道流固耦合三维动力有限元模型;进行2种流体介质下管道结构动力响应对比。通过研究管道在冲击气流作用下的振动机理和振动特性,从管道结构入手提出了该放空管道振动控制的措施,给出了减振方案。建立减振方案中管道的流固耦合动力有限元模型,进行仿真分析并与原方案计算结果进行了对比,发现管道系统的振动得到大幅度的降低,验证了所提出的减振方案可以对管道振动进行合理有效的控制,确保了管道振动幅度在安全裕度内。 相似文献
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核级恒力弹簧吊架回转臂的应力分析 总被引:1,自引:0,他引:1
恒力弹簧吊架是核电站管道支撑及悬吊主要设备.由于核电站项目的特殊性,恒力弹簧吊架零部件的应力分析与强度计算是设计过程中必不可少的环节,是恒力弹簧吊架正常稳定工作的保证.这里对三连杆恒力弹簧吊架进行力学分析,得到弹簧力与回转臂转角的关系曲线.应用三维造型软件建立了回转臂的实体几何模型,给出了回转臂模型简化方法.利用有限元方法对回转臂进行应力分析,得到回转臂不同转角下应力分布规律.分析结果表明本设计满足核级电站产品的设计要求. 相似文献
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Sang-Nyung Kim Seon-Hong Hwang Ki-Hoon Yoon 《Journal of Mechanical Science and Technology》2005,19(5):1206-1215
The thermal stratification phenomena, frequently occurring in the component of nuclear power plant system such as pressurizer
surge line, steam generator inlet nozzle, safety injection system (SIS), and chemical and volume control system (CVCS), can
cause through-wall cracks, thermal fatigue, unexpected piping displacement and dislocation, and pipe support damage. The phenomenon
is one of the unaccounted load in the design stage. However, the load have been found to be serious as nuclear power plant
operation experience accumulates. In particular, the thermal stratification by the turbulent penetration or valve leak in
the SIS and SCS pipe line can lead these safety systems to failure by the thermal fatigue. Therefore in this study an l/lO
scaledowned experimental rig had been designed and installed. And a series of experimental works had been executed to measure
the temperature distribution (thermal stratification) in these systems by the turbulent penetration, valve leak, and heat
transfer through valve. The results provide very valuable informations such as turbulent penetration depth, the possibility
of thermal stratification by the heat transfer through valve, etc. Also the results are expected to be useful to understand
the thermal stratification in these systems, establish the thermal stratification criteria and validate the calculation results
by CFD Codes such as Fluent, Phenix, CFX. 相似文献