Transient thermal stresses and displacements in a transversely isotropic semi-infinite circular cylinder subjected to an arbitrary surface heat generation and a convective heat loss

The transient thermal stresses and displacements in a traction-free, transversely isotropic, semi-infinite circular cylinder subjected to a convective heat loss on the end surface is analyzed by means of a set of stress functions and a generalized Fourier-integral representation for exponential function.The purpose of this paper is to present the results of theoretical analysis which considers the effects of the thermal and elastic anisotropes of the material properties on the thermal stresses and displacements in the transversely isotropic, semi-infinite circular cylinder due to an arbitrary cylindrical surface heat generation.A detailed numerical result of the thermal stresses and displacements is given for various values of the ratios of the thermal conductivity coefficients, Young's moduli and linear thermal expansion coefficients in the axial and radial directions and it is demonstrated that the sensivity of the maximum stress and displacement to the anisotropy of the thermal conductivity coefficient is significant.     

Three-dimensional transient thermal stresses of reactor graphite subjected to internal heat generation and asymmetric surface heating

The present paper is concerned with three-dimensional transient thermal stresses of graphite in a nuclear reactor. In analyzing this problem, reactor graphite may be approximated by a transversely isotropic finite circular cylinder subjected to internal heat generation and asymmetric heating on an end surface. Thermal stresses are analyzed by means of the transversely isotropic potential functions method proposed by Takeuti and Noda. Numerical calculations were carried out for a special type of heating conditions, and time variations of temperature and thermal stresses of graphite are shown in figures.     

碳纤维复合材料薄壁圆筒的轴向导热系数测试

碳纤维复合材料薄壁圆筒为各向异性导热,其轴向导热系数是筒体温度场理论计算、成型工艺优化的重要参数。碳纤维复合材料圆筒由于较小的截面面积给筒体加热、热量有效传递带来了较大困难。本文以平板材料导热系数的稳态法测试国家标准为基础,基于傅里叶一维稳态导热原理,设计了一套用于薄壁圆筒轴向导热系数测试的装置,采用双试件对称加热、辐射换热防护及热对流环境控制等实现了热量沿筒体轴向的有效传导,利用该装置对导热系数已知的铝筒进行测试,验证了该装置设计的可行性,得到了碳纤维复合材料薄壁圆筒的轴向导热系数为（4.60±0.13） W/(m•K)。     

Conjugate heat transfer and thermoelastic analysis of heat-generating rods

The exact mathematical formulation and solution of a number of problems dealing with temperatures and stress fields in canned cylinders with arbitrary internal power distribution and fully developed axial turbulent flow are discussed. The problem areas are: (1) the exact linear, thermal, thermoelastic and mechanical stress analysis for a rod in symmetric flow with general integral end force/displacement relations; (2) heat transfer from a clad cylinder with a symmetric heating and temperature dependent conductivity; and (3) asymptotic linear thermal analysis of a rod and associated sub-channel from a square or triangular array.     

对流换热条件下换热器管板的应力分析

给出对流换热条件下换热器管板中应力场的有限元分析方法。分析中将管板布管区折算为受管孔削弱并被管束支承的横观各向同性均质等效板；在计算位移场时采用具有附加内部自由度的ｗｉｌｓｏｎ非协调元，以保证计算应力的精度与温度场精度相匹配。计算结果得到了试验验证。典型算例说明过厚的管板将引起过大的温度应力。对于核工业中各种以温度载荷为主的换热器，应注意合理选择管板厚度。     

MOSSBAUER STUDIES OF MAGNETIC ANISOTROPY OF AMORPHOUS Fe-(Co, Cr)-Zr ALLOYS

Magnetic anisotropies and hyperfine fields of amorphous a-Fe-(Co, Cr)-Zr alloys, their temperature and thermal stress effects were studied by using a Mossbauer spectroscopy. The results are in the following: A tensile stress field is easily created during the material production process, having the plane anisotropy to be increased for the alloys containing strong ferromagnetic coupling such as Fe-Co and Fe-Ni; a pressure stress field is easily produced, making the perpendicular anisotropy increase for the alloys containing antiferromagnetic coupling such as Fe-Cr and Fe-Mn. Introducing the new idea of attractive and repulsive forces, the fact was explained well that the dependence of anisotropies on the average outer electron concentration of 3d transition metal is similar to that of the average hyperfine field.     

Transient thermal stresses in a bonded composite hollow circular cylinder under symmetrical temperature distribution

A general treatise for the transient thermal stress problem of a composite circular cylinder made by bonding is described under a symmetrical temperature distribution. Analysis is developed by stress function method by the aid of Laplace transforms. Numerical examples are illustrated for the hollow composite cylinder with several radius-ratios made by the different materials due to transient heating at the internal surface by liquid.     

About the validity of analytical approximations for temperature and stress for actively cooled windows during thermal loading

The verification of analytical approximations for temperature and stresses during thermal loading is done for ceramic edge-cooled windows for the stellarator W7-X by comparison with more accurate numerical calculations. Numerical calculations show that a steady state temperature and stress approximations assuming edge-cooled circular plates can be applied only in the case when radiative cooling from a surface is neglected. The prediction for poor thermal conductivity ceramics under high heat flux load based on simple analytical equations can result in considerable mistakes in the temperature and, consequently, stress values. Even the prediction of the qualitative tendency of temperature and stress behaviour as a function of the window size can be wrong.     

A structural analysis of the circular cylinder with multi holes under thermal loading

A structural analysis of the circular cylinder with multi holes is performed using the finite element analysis program . This structure is an analytical model of the capsule used for material irradiation tests. The temperature distributions of the cylinder due to gamma heating are obtained and various parameters, such as specimen size, quantity of specimens and gap sizes between the holder and the specimen are considered in the analysis to obtain the thermal and mechanical characteristics. To assess the structural integrity of the capsule, stress analysis under thermal loading is also performed. The analysis results show that, in all specimens, the peak temperature occurred, and is significantly dependent on gap sizes between the holder and the external tube or the specimen. The stress of the cylinder, under thermal loading, is lower than the allowable stress of the material used.     

Thermal stress in a bimodulus thick cylinder

Certain materials are known to behave differently under tension and compression. This reports an investigation of a simple thermal stress problem based on the bimodulus elasticity in the framework of the classical-type uncoupled thermoelasticity. Because of an unavoidable complexity of three-dimensional analysis in bimodulus elasticity, as a fundamental illustration we consider herein an axisymmetric plane strain state of a thick orthotropic circular cylinder under axisymmetric heat conditions. A system of transcendental simultaneous algebraic equations with respect to eight unknowns are derived. Numerical analyses are carried out for a steady-state temperature field and for a quasi-stationary state with internal heat generation. Results of calculations show that the states of a cylinder are affected significantly by the difference between tensile and compressive moduli of elasticity.     

Length effects of unsteady thermal stresses in a finite short circular cylinder with an arbitrary heat supply

An unsteady thermoelastic study, taking consideration of the length effects, was made of a finite short circular cylinder under an arbitrary heat supply along its cylindrical surface in the longitudinal direction. The analysis was treated by the thermoelastic potential method using a general form of the Love's displacement function which has not so far been used. The results obtained were compared with those of an approximate solution for the finite cylinder using Saint-Venant's principle. From the results the effects of the length-to-diameter ratio evidently appear in the transient thermal stress distributions for the finite short cylinder.     

Symmetric thermoelastic stress in cylinders by the lanczos-chebyshev method

The Lanczos-Chebyshev method is used to reduce the linear heat conduction equation to a set of ordinary differential equations. The eigenvalues and eigenvectors defining the axial decay of temperature components in a solid cylinder are obtained. The thermal stresses are found by applying the same reduction technique to the linear displacement equations, considering thermal and self-equilibrating stress fields separately. Numerical examples are used to illustrate the speed and accuracy of the method in comparison with semi-analytical Bessel function type solutions and to show the end effects in cylinders.     

Effects of thermal load and cooling condition on weld residual stress in a core shroud with numerical simulation

Stress corrosion cracking (SCC) in the heat affected zone is the primary damage form due to weld residual stress, corrosion and neutron irradiation environment in the core shroud of a boiling water reactor. The distribution of weld residual stress around a weld is necessary to be clarified to evaluate the structural integrity of core shroud for SCC. Moreover, studying the effects of welding parameters on residual stress on reducing the residual stress is very important to suppress the initiation and propagation of SCC.In this paper, we used a finite element method (FEM) to clarify the distribution of weld residual stress around the sixth horizontal weld (H6a) between the lower ring and the cylinder in the core shroud. The simulation results of axial stress were consistent with the experimental results at the inside and outside surfaces of the core shroud, respectively. The effects of thermal loads and cooling conditions were also investigated with the same model. We simulated the welding progress with water cooling on the inside and outside surfaces of the core shroud in order to study the influence of cooling conditions on the residual axial stress around the weld. The simulation results indicated that water cooling decreased the residual axial stress at the same side due to changing the temperature-affected fields. Moreover, with fixing the peak temperatures of weld passes, the simulation results of the distribution of residual axial stress by the thermal loads with different heating time were compared. The simulation results suggested that the heating time was expected to be longer and the heat flux to be smaller for reaching the small tension residual axial stress or even compression stress around the H6a weld.     

Proposal of a new estimation method of thermal ratchetting behavior of fast breeder reactor components

A new method for estimating the thermal ratchetting behavior of a cylinder subjected to an axially moving temperature distribution is proposed in this paper. This method considers the contribution of both the hoop membrane stress and the axial bending stress to the ratchetting behavior. Work hardening of the material also is considered for the stress-strain behavior which is assumed in the estimation method. Results predicted by this method agree well with the results obtained by finite element modelling and experimental results.     

Seismic analysis of cracked reactor vessels

This paper deals with the dynamic response of a thin finite, elastic circular cylindrical shell representing a reactor vessel to time-dependent loadings symmetrical with respect to the axis of the cylinder. The shell contains an axial through-crack of length 2c. The dynamic counterpart of Donnell's shell equations are used in this investigation. Extensive numerical results are presented for stress intensity factors in aluminum and steel vessels and results are discussed.     

安全壳喷淋泵转子系统热冲击特性分析

为研究1 000 MW级核电站用安全壳喷淋泵的热冲击特性,对热冲击作用下泵内部流场进行了数值计算。热冲击工况下泵内径向力逐渐变大,波动更为剧烈;轴向力逐渐变小;径向力和轴向力的波动趋势与常温工况的一致。将内流场模拟得到的热载荷及压力载荷加载到结构体上,分析热冲击下转子系统过流部件的温度分布,并分析其热应力与机械应力分布规律。结果表明：热应力对结构的破坏占主要作用;最大的热应力集中在轮毂上,最大的机械应力在轮毂与叶片的交界处;叶片上热应力和机械应力分布均满足叶根至叶顶依次减小的规律。     

Transient thermal stresses in an orthotropic finite rectangular plate due to arbitrary surface heat-generations

The transient thermal stresses in an orthotropic finite rectangular plate due to arbitrary surface heat-generations on two edges are studied by means of the Airy stress function.The purposes of this paper are to present a method of determining the transient thermal stresses in an orthotropic rectangular plate with four edges of distinct thermal boundary condition of the third kind which exactly satisfy the traction-free conditions of shear stress over all boundaries including four corners of the plate, and to consider the effects of the anisotropies of material properties and the convective heat transfer on the upper and lower surfaces on the thermal stress distribution.     

Creep of a thin anisotropic circular plate containing a circular hole at the centre

An analysis to study the creep behaviour of a circular plate with a circular hole at the centre under uniform stretching at the boundary has been carried out. The material of the plate is assumed to be anisotropic and homogeneous. The analysis is based on a time-hardening law and the stresses and strains have been calculated using procedure of successive approximations. All the results have been obtained in a non-dimensional form and compared with the corresponding values for the isotropic case. The redistributed stress and the ultimate stress and strain distributions are found very much different from the initial distributions. At the outer boundary of the plate the effect of anisotropy on stress and strain is negligibly small, whereas at the inner boundary this effect is quite pronounced. All the important results obtained in this study have been presented graphically.     

TRISO燃料颗粒等效导热系数理论模型研究

三层各向同性碳包覆（TRISO）燃料颗粒由核芯和4层包覆层组成,具有良好的裂变产物包容能力,其等效导热系数是计算弥散微封装燃料等效导热系数的重要基础。本文首先从球坐标下基本导热方程出发,基于多相固体宏观等效导热理论,建立了TRISO燃料颗粒等效导热系数理论计算模型;然后,结合固-固二元复合材料等效导热系数Chiew-Glandt模型分析了锆基微封装燃料（M3）芯体等效导热系数。结果表明,本文开发的模型可有效模拟TRISO燃料等效导热系数。基于开发的TRISO等效导热系数模型计算获得了全陶瓷微封装燃料（FCM）的等效导热系数。