THERMAL ELASTIC-PLASTIC STRESS ANALYSIS OF SYMMETRIC ALUMINUM METAL-MATRIX COMPOSITE LAMINATED PLATES UNDER UNIFORMLY DISTRIBUTED TEMPERATURE

In this study, a thermal elastic-plastic stress analysis is carried out on simply supported symmetric cross-ply (0°/90°) 2 and angle-ply (5°/85°) 2 , (15°/-15°) 2 , (30°/-30°) 2 , (45°/-45°) 2 , (60°/-60°) 2 , (15°/60°) 2 , (15°/75°) 2 , (75°/-75°) 2 aluminum metal-matrix laminated plates under the uniform temperature distribution across the thickness of the plates. The Tsai-Hill criterion is used as a yield criterion. Differential equations are solved with a sufficiently large number of integration intervals of the temperature. The composite material is assumed to be strain hardening linearly. The magnitude of the residual stress components in the cross-ply laminated plate are higher than those in the angle-ply laminated plates. Plastic yielding occurs in all the laminated plates at the same temperature.     

THERMALLY FORCED VIBRATIONS OF MODERATELY THICK POLYGONAL PLATES

Bruno A. Boley was among the first to analyze thermally induced vibrations of beams and plates, a subject of paramount importance in various fields of engineering and space technology. The present paper is concerned with moderately thick plates within the Mindlin theory. A correspondence of the solution to the simpler one of an auxiliary prestressed thin plate with effective parameters is derived. By another projection the solution of the thermal deflection can be further reduced to that of two effectively stressed membranes. The correspondence of deflections is extended to moments and shear forces in the case of neglected rotatory inertia. The class of solutions, however, is restricted to simply supported plates with straight edge elements. The representation in the frequency domain is understood and frequency response functions for the deflection of parallogram plates are presented, where a Boundary Element Technique with Green's functions of rectangular domains is used.     

GEOMETRICALLY NONLINEAR ANALYSIS OF TIMOSHENKO BEAMS UNDER THERMOMECHANICAL LOADINGS

Considering the axial extension and the transversal shear deformation, geometrically nonlinear governing equations for static deformations of Timoshenko beams subjected to thermal as well as mechanical loadings are formulated. As an example, on the basis of the governing equations, thermal postbuckling response of an immovably pinned-fixed Timoshenko beam subjected to a static transversely nonuniform temperature rise is numerically analyzed by using a shooting method. Characteristic curves showing the relationships between the beam deformation and temperature rise are presented. The thermal postbuckled configurations and the equilibrium paths of the beam are presented. In particular, the effects of shear deformation on the buckling response are quantitatively investigated. The numerical results show, as we know, that shear deformation effects become significant with decrease of the slenderness and with increase of the shear flexibility.     

NONLINEAR MAGNETOTHERMOELASTICITY OF ANISOTROPIC PLATES IMMERSED IN A MAGNETIC FIELD

A geometrically nonlinear theory of magnetothermoelasticity of electroconductive anisotropic plates in a magnetic field is developed. In this context, the Kirchhoff hypothesis is adopted for the plate modeling and the geometrical nonlinearities are considered in the von Kármán sense. In addition, the assumptions related to the distribution of electric and magnetic field disturbances through the plate thickness as proposed by Ambartsumyan and his collaborators are adopted. Based on the electromagnetic equations (i.e., the ones by Faraday, Ampère, Ohm, Maxwell, and Lorentz), on the modified Fourier law of heat conduction, and elastokinetic field equations, the three-dimensional coupled problem is reduced to an equivalent two-dimensional one appropriate to the theory of plates. The theory developed herein enables one to investigate the interacting effects among the magnetic, thermal, and elastic fields in orthotropic thin plates. As a special case, the problem of the free vibration of simply supported plate strips immersed in a transversal magnetic field is considered. Effects of the directionality property of the constituent material, magnetic and temperature fields, and electric conductivity, as well as thermal expansion coefficients, on the characteristics of vibrational behavior of the plate strips are investigated.     

THERMAL ELASTOPLASTIC ANALYSIS OF PLATES WITH CIRCULAR HOLES

The present paper deals with ehstoplastic thermal stresses in a thin plate with an insulated circular hole. The hole causes a disturbance in temperature distribution when the plate is heated uniformly through the thickness. A finite-difference method is utilized to determine the temperature distribution from the steady-state heat conduction equation. An incremental theory of successive elastic approximations is used in the analysis of the elastoplastic stresses in the plate.     

THERMOMECHANICAL ANALYSIS OF FUNCTIONALLY GRADED CYLINDERS AND PLATES

The dynamic thermoelastic response of functionally graded cylinders and plates is studied. Thermomechanical coupling is included in the formulation, and a finite element model of the formulation is developed. The heat conduction and the thermoelastic equations are solved for a functionally graded axisymmetric cylinder subjected to thermal loading. In addition, a thermoelastic boundary value problem using the first-order shear deformation plate theory (FSDT) that accounts for the transverse shear strains and the rotations, coupled with a three-dimensional heat conduction equation, is formulated for a functionally graded plate. Both problems are studied by varying the volume fraction of a ceramic and a metal using a power law distribution.     

DEFORMATION CONTROL OF LAMINATED COMPOSITE PLATES CONTAINING PIEZOELECTRIC LAYERS UNDER THERMAL LOADING

A composite plate containing piezoceramics on both the upper and bottom surfaces is considered. Based on the piezoelectricity with consideration for the coupling between the strain field and the electric field, a finite element formulation is developed. An eight-node three-dimensional brick element is used, and three-dimensional incompatible modes are introduced to take into account the bending behavior of the structure. The response of the structure and the sensor electrical outputs subjected to thermal loading as well as the required voltage that should be applied to reduce the deflection resulting from thermal loading are analyzed. In addition, this study also analyzes the effect of coupling between the strain field and the electrical field. It shows that the coupling effect may not be negligible; the larger the piezoelectric constant, or the thinner the main structure, the larger the coupling effect will be.     

HIGH TEMPERATURE THERMOMECHANICAL ANALYSIS OF CERAMIC COATINGS

This paper investigates the thermomechanicai response of ceramically coated metal parts in elevated thermal environments. This is made possible through the development of an improved finite element algorithm that enables the efficient and stable solution of the inherently nonlinear elastic-creep (inelastic) type thermomechanicai field equations associated with high temperature. Based on the improved algorithm, the results of several numerical experiments are presented. These illustrate the significant influence of inelastic behavior in generating residual stress fields.     

AN APPROXIMATE APPROACH TO NONLINEAR THERMAL BENDING OF SHALLOW SANDWICH SHELLS AND FLAT PLATES

By extending the well-known Berger approach for single-layer isotropic elastic plates, an approximate method of analysis for the nonlinear bending of shallow sandwich shells is proposed. Governing field equations are derived for shallow sandwich shells subjected to mechanical as well as thermal effects. Numerical calculations are carried out for large deflections of shells and flat plates due to a temperature difference between the upper and lower faces, and the applicability of the approximate field equations is discussed.     

NONLINEAR RESPONSE OF GEOMETRICALLY IMPERFECT STIFFENED FLAT PANELS UNDER THERMOMECHANICAL LOADING

A study of the nonlinear response of orthogonally stiffened isotropic flat panels exposed to a temperature rise and a lateral pressure field is presented. A theoretical analysis and the numerical results emphasize the effects played by the bi/uniaxial stiffeners and unavoidable initial geometric imperfections on the thermomechanical load-carrying capacity of stiffened panels, and pertinent conclusions are outlined.     

THERMAL BUCKLING ANALYSIS OF ISOTROPIC AND COMPOSITE PLATES WITH A HOLE

Abstract

We analyze thermal buckling of both circular isotropic plates and square antisymmetric angle-ply laminates with a hole in the middle, and subject to a uniform temperature rise, by either closed form solution for the former or finite-element method for the latter. Thin-plate theory is used to analyze the isotropic plates. However, a high-order displacement theory including high-order terms along the transverse direction taking into account transverse normal strain is used in the case of laminates. Results for the isotropic plates indicate that in contrast to the reduction in mechanical buckling loads due to the hole, the thermal buckling temperature actually rises as the size of the hole increases, which indicates that the effect on stress reduction exceeds that on stiffness decrease. Results are more complicated for laminated plates, due to anisotropy.     

3-D CONJUGATE ANALYSIS OF COOLED COATED PLATES AND HOMOGENIZATION OF THEIR THERMAL PROPERTIES

To predict the aerothermal behavior of a transpiration cooled plate, a multiscale approach based on the homogenization method of periodic material structures is presented here. This method allows calculation of effective equivalent thermophysical properties either for each layer or for the multilayer of superalloy, bondcoat, and thermal barrier coating (TBC). From the 3-D conjugate flow and heat transfer analysis, the stationary state is extracted and transferred to the microscale unit cell discretized by finite elements. The analysis proves for different cooling configurations a significant decrease in the amount of cooling fluid to obtain a desired superalloy temperature. Beyond, the hole outlet shaping leads to a reduction of the thermal gradients on the multilayer. The effect of the different cooling designs on the effective conductivities are discussed then. Finally, the influence of the selection of the unit cell position on these effective thermal properties is investigated.     

THERMOELASTIC ANALYSIS OF LAMINATED PLATES. I: SYMMETRIC SPECIALLY ORTHOTROPIC LAMINATES

Thermally induced deformations and stress resultants in symmetric laminated plates are analyzed. The method of M. Levy is used to study the transverse bending of a specially orthotropic laminate having two simply supported edges and subject to a temperature distribution that does not vary in a direction parallel to the simple supports. A solution is also obtained for the problem of in-plane stretching of the plate middle surface caused by a general three-dimensional temperature field. As an illustrative example, the thermoelastic response of a unidirectionally fiber-reinforced plate to a temperature variation that is linear in the thickness direction is computed.     

不同放电倍率条件下的锂电池温度场分析

锂电池作为可再生能源领域中储能系统的核心部件,其安全运行至关重要,然而锂电池在放电过程中的温升现象会严重影响其安全运行与使用寿命,甚至会导致事故的发生,因此,研究锂电池的工作温度对其安全的影响具有重要意义.本文首先根据实验数据分析了锂电池在充放电循环过程中的温度情况,分析发现:随着放电倍率的增大,锂电池在放电过程中的温...     

FLEXURAL CHARACTERISTICS AND LAYUP OPTIMIZATION OF LAMINATED COMPOSITE PLATES UNDER HYGROTHERMAL CONDITIONS USING LAMINATION PARAMETERS

The flexural characteristics and layup optimization of laminated composite plates are examined in environmental conditions of temperature and moisture. The deflection of laminated composite plates is analyzed in the design space of 12 lamination parameters. The layup optimization for minimizing the deflection of laminated composite plates is carried out using all 12 lamination parameters as design variables. Mathematical programming methods are used for optimization. In hygrothermal conditions, the maximum deflection of laminated composite plates with in-plane hygrothermal stresses can be reduced by optimized nonsymmetric laminate configurations.     

光伏组件在非标准测试条件下的能量分布

该研究基于非标准测试条件,结合五参数电学模型、热阻模型和损失模型,提出一种评估光伏组件能量分布的耦合模型.通过模拟数据和实验数据的对比,验证该模型在模拟光伏组件发电量和太阳电池温度方面的准确性,并研究非标准测试条件下光伏组件的运行状态和能量分布情况.结果表明,在某个晴天下,对于一个实际运行的光伏组件,21.9％的入射太...     

风速波动时风电场动态特性分析

为了分析风速波动时风电场的电压特性,建立了考虑风机组尾流效应的风机输入风速模型及考虑风机输入风速不同的风电场动态模型,并对风电场采用不同模型时风电场的输出进行仿真比较,结果表明在分析风速波动风电场动态特性时,采用考虑风机间尾流效应和风电场内机组排列布置的风电场模型能够相对准确地反映实际风电场的动态特性,而采用不考虑风机尾流效应的风电场单机模型,夸大了风电场对系统的影响.同时对风电场分别采用恒速风电机组和双馈变速风电机组时的输出特性进行仿真,分析了以上两种风电机组的无功电压特性.     

冰在平板上接触熔化的分析

分析了矩形平板下冰在压力与温差共同作用下产生的熔化过程。利用接触熔化理论求得压力分布、熔化边界层厚度、作用力与熔化速度关系的表达式,进而分析和得到圆形平板下冰熔化的结果,并分别与压力、温差驱动熔化的结果进行了比较,给出一些有益的结论。     

太阳辐照条件下土壤内温湿度场的动态模拟

根据质量守恒和能量守恒定律，同时对土壤非饱和区热湿迁移机理进行分析，建立了土壤非饱和区热湿迁移的理论模型。通过数值分析，模拟了太阳辐照条件下土壤内温度和含水率分布曲线。