湿热状态下倾斜复合材料板混沌运动区域分析

在考虑湿热影响的基础上,利用Melnikov函数研究了倾斜复合材料矩形板的混沌运动,并讨论分析了倾斜角、湿度、温度、长宽比、板厚对复合材料矩形板发生混沌运动区域影响。     

Thermal Stressed State of a Conducting Plate under the Action of Electromagnetic Pulses

We give the mathematical formulation of a dynamic boundary-value problem of electromagnetothermoelasticity for a conducting nonferromagnetic plate subjected to adiabatic deformation by a pulsed electromagnetic field. We find exact and approximate solutions of model problems for magnetic impacts with finite velocity or under the action of electromagnetic pulses and study the limits of applicability of polynomial approximations for the unknown functions across the thickness of the plate used for the determination of approximate solutions of the considered problems.     

纳米孔 SiO2多层隔热材料的制备和结构优化设计

以SiO2粉体为主要原料,加入石英纤维和硬硅钙石晶须作为增强材料,通过湿法工艺制备了纳米孔SiO2.制备的纳米孔SiO2密度为0.3g/cm3,孔隙率为85％左右.孔隙直径主要分布在20到80nm之间.由于大量纳米孔的存在,纳米孔SiO2中固相导热和对流传热大大降低.为了降低纳米孔SiO2的高温辐射传热,采用辐射屏蔽层与纳米孔SiO2叠层复合来制备纳米孔SiO2多层隔热材料.采用有限元方法,通过传热计算得到纳米孔SiO2多层隔热材料等效导热系数随辐射屏蔽层的发射率、层密度及工作温度的变化规律.提出了纳米孔 SiO2多层隔热材料的结构优化设计方案.     

Influence of Thermal Properties on the Sensitivity of Thermal Wave Interferometry for the Characterization of Plasma-Sprayed Coatings

Thermal wave interferometry (TWI) is used as a means for measuring the thermal properties of plasma-sprayed coatings. The solution of the inverse problem is influenced by the magnitude of the signal-to-noise ratio and the amount of data available. This is investigated using a sensitivity analysis. The critical factors that determine the accuracy and the limitations of the technique are discussed. Numerical and experimental thermal wave tests confirm the range of applicability and the accuracy of TWI for measuring thermal properties.     

保护热板法测量参考物质导热率的研究

保护热板法是测量绝热材料导热率的一种绝对方法.介绍了实验装置的测量原理以及实验过程,采用德国国家物理技术研究院(PTB)的参考物质,在此装置上进行导热率测量实验.与欧洲十七个国家实验室和研究机构的测量结果进行了对比,该装置测量的结果处于比对结果的中间,合成相对标准不确定度为0.8×10-2.结果表明,该装置对此参考物质的测量结果具有较好的可靠性.     

Active Damping of Nonstationary Vibrations of a Three-Layer Electro-Viscoelastic Composite Plate

Strength of Materials - A method for constructing nonstationary vibration equations for electro-viscoelastic composite plates with their active damping is described. The problem is solved in an...     

On One Method of Solving Nonstationary Heat-Conduction Problems for Multilayer Structures

As applied to the solution of the heat-conduction problem for a two-layer structure, the Fourier method is used jointly with the orthogonal Bubnov-Galerkin method. An important feature is the introduction of additional boundary conditions, the need for which is explained by the appearance of an additional parameter μ after the separation of the variables in the input differential equation. The additional boundary conditions are derived from the basic differential equation by differentiating it at the boundary points.__________Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 78, No. 2, pp. 24–28, March–April, 2005.     

Influence of Transverse Anisotropy and Type of Boundary Conditions on the Stress State of a Circular Transtropic Plate

Strength of Materials - On the basis of the equations of the nonclassical model of bending of transtructural plates of average thickness, which takes into account the influence of normal stress...     

换热边界下梯度功能材料板瞬态热应力研究

用有限元和辛普生法,研究了由ZrO2和Ti-6Al-4V组成的梯度功能材料板的瞬态热应力问题,检验了方法的正确性,给出了对流换热边界下的瞬态热应力场分布.结果表明:材料组分的分布形状系数M、对流换热系数和环境介质温度的变化对该材料板的瞬态热应力场分布均有明显的影响;在本研究相同条件下,该材料无限自由长板在金属和陶瓷附近板内为压应力,而在板中部为拉应力.此结果为该材料的设计制备提供了准确的理论计算依据.     

多层薄膜的热应力研究

薄膜的应力对薄膜性能有着重要的影响.考虑了各个膜层弹性模量不同的情况,建立了多层薄膜热应力的数理模型,计算了典型多层薄膜体系中应力的分布.如果使用0级近似,每层薄膜中的热应力是由基底和膜层之间的热失配决定的,而不受其它膜层的约束;而使用一级近似,每一膜层中的热应力受其它膜层的影响.这种方法为多层薄膜应力的评价提供了依据.     

介质多层膜的热吸收

根据薄膜光学基本理论,利用一级近似数学方法,给出S,P偏振态平行光在两弱吸收介质边界反射率及透射率的简单表达式,并依此研究了弱吸收介质单层膜及多层膜的热吸收。结果表明,单一膜层的热吸收率,在膜层参数确定的条件下,不仅取决于此膜层材料的消光系数,而且取决于相邻膜层的消光系数。     

The Influence of the Blade Airfoil Bend Angle on Its Thermal and Thermal Stress State under Nonuniform Heating

The author studied the influence of the turbine-blade-airfoil bend angle on the blade thermal and thermal stress state under nonsteady-state temperature conditions. It is shown that at nonuniform heating, the influence of the bend angle on the level of temperatures and temperature distribution over the airfoil is insignificant, whereas the level of thermal stresses on the blade edges changes appreciably due to internal constraint. It has been found that high levels of thermal stresses may occur in turbine rotor and nozzle blades irrespective of the magnitude of the bend angle when their thermal bending due to nonuniform heating is restricted by the external constraint.     

Determination of Thermal Diffusivity by Nonstationary Spot Heating

Technical Physics Letters - A thermographic express method for determining the coefficient of thermal diffusivity (a) of platelike objects is presented. It may be regarded as a modification of, and...     

Na2SO4/SiO2定形复合储热材料的性能研究

通过传统热分析法和差示扫描热分析仪(DSC)研究了Na2SO4/SiO2复合材料的储热性能。研究表明Na2SO4/SiO2有很高的储热密度(180～210J/g)和良好的抗热震稳定性,得出了这种材料较完整的热工性能参数,为蓄热器的设计提供了必要的热工计算参数。