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1.
将双模量板等效为两个各向同性小矩形板组成的层合板,假定该层合板的中性面即为两个小矩形板的交界面。根据中性面上应力为零且薄板全厚度上应力的代数和为零,推导了双模量矩形薄板的中性面位置。本文采用严宗达提出的带补充项的双重正弦傅里叶级数通解,该通解可以适用于任意边界条件的矩形薄板且不需要叠加或者重新构造。联立边界条件和控制方程,求得通解中的待定系数并代入到通解中,即可得到任意边界条件下双模量矩形薄板的弯曲解析解。与有限元结果比较,本文结果符合工程精度要求。  相似文献   
2.
Yanshuang Kang 《中国物理 B》2022,31(5):56104-056104
Based on the free-energy average method, an area-weighted effective potential is derived for rectangular corrugated nano-pore. With the obtained potential, classical density functional theory is employed to investigate the structural and thermodynamic properties of confined Lennard-Jones fluid in rectangular corrugated slit pores. Firstly, influence of pore geometry on the adsorptive potential is calculated and analyzed. Further, thermodynamic properties including excess adsorption, solvation force, surface free energy and thermodynamic response functions are systematically investigated. It is found that pore geometry can largely modulate the structure of the confined fluids, which in turn influences other thermodynamic properties. In addition, the results show that different geometric elements have different influences on the confined fluids. The work provides an effective route to investigate the effect of roughness on confined fluids. It is expected to shed light on further understanding about interfacial phenomena near rough walls, and then provide useful clues for the design and characterization of novel materials.  相似文献   
3.
自适应光学校正技术可有效提升固体板条激光器的光束质量,但随着激光器输出功率的提升,输出光束口径逐渐增加,系统体积逐渐增大,自适应光学校正系统的设计难度也增加了。因此,在满足自适应光学校正系统中共轭探测等需求的前提下,统筹优化系统的尺寸参数,同时实现波前相位、光束质量评估等多参数的检测具有一定的研究意义。本文在系统整体尺寸为350 mm×180 mm×220 mm(长×宽×高)的条件下,研究实现了板条激光器输出160 mm×120 mm矩形光束多参数的检测。针对探测口径大、筒长限制、长出瞳距等技术要求,首先,利用双高斯初始结构的消像差特点,结合非球面技术,采用大倍率光束压缩后分光探测的设计方案,实现多参数的同时探测。其次,基于摄远成像和共轭成像等原理,确定系统初始参数。接着,建立仿真模型分析系统的成像质量和公差,为实验的搭建提供依据。最后,搭建实验平台验证设计结果。结果表明:所设计系统可在满足物像共轭、尺寸约束等条件下,实现对大口径矩形光束的共轭波前探测、光强均匀度检测和光束质量评估。实验测得被测光束β因子为1.24倍衍射极限,均匀度为73.8%,满足技术指标要求。  相似文献   
4.
Based on the primal mixed variational formulation, a stabilized nonconforming mixed finite element method is proposed for the linear elasticity on rectangular and cubic meshes. Two kinds of penalty terms are introduced in the stabilized mixed formulation, which are the jump penalty term for the displacement and the divergence penalty term for the stress. We use the classical nonconforming rectangular and cubic elements for the displacement and the discontinuous piecewise polynomial space for the stress, where the discrete space for stress are carefully chosen to guarantee the well-posedness of discrete formulation. The stabilized mixed method is locking-free. The optimal convergence order is derived in the $L^2$-norm for stress and in the broken $H^1$-norm and $L^2$-norm for displacement. A numerical test is carried out to verify the optimal convergence of the stabilized method.  相似文献   
5.
极端工况双矩形腔静压推力轴承动态特性   总被引:1,自引:0,他引:1  
静压推力轴承动态特性受润滑油黏度、油膜厚度和油腔面积等因素影响, 极端工况运行过程中经常承受阶跃载荷或正弦载荷作用, 突加载荷将导致静压推力轴承动态特性改变, 表现为轴承的抗冲击能力和恢复平衡所需时间的变化. 为获得高速重载微间隙极端工况条件下双矩形腔静压推力轴承动态特性, 分别在不同油膜厚度、不同润滑油黏度以及不同油腔尺寸条件下对双矩形腔静压推力轴承的动态性能进行理论分析, 探讨了阶跃载荷作用下润滑油黏度、油膜厚度和油腔面积对轴承动态性能的影响, 揭示了油膜动态变化规律, 探究了正弦载荷作用下双矩形腔静压推力轴承的稳定性. 结果表明: 润滑油黏度、油膜厚度和油腔尺寸变化对其动态性能有很大的影响. 润滑油黏度越大、油膜厚度越小、油腔面积越大突加载荷作用下润滑油膜抵抗冲击的能力越强, 旋转工作台受到突加外力作用下恢复至平衡状态所用时间越短. 双矩形腔静压推力轴承油膜具有较大的阻尼系数, 轴承具有极强的抵抗正弦加载作用的能力   相似文献   
6.
This review gives an overview of the evolution of the technology of condensed mode cooling, primarily for the case of ethylene polymerization on supported catalysts in fluidized bed reactors. It is well known that this mode of heat removal is quite effective in allowing polyolefin manufacturers to increase significantly production rates. What is perhaps less well understood are all of the issues that, in addition to the effect of the latent heat of vaporization of injected liquid components, also have an impact on the rate of production and behavior of the reactor. However, the liquid components injected into the reactor can vaporize rapidly under full‐scale conditions, leaving behind several heavy components (with respect to ethylene) that have numerous effects on how the particles behave, on the reaction rate, and on fluidization, fouling, and other parameters related to reactor and process performance.  相似文献   
7.
The current paper presents a thorough study on the pull-in instability of nanoelectromechanical rectangular plates under intermolecular, hydrostatic, and thermal actuations. Based on the Kirchhoff theory along with Eringen's nonlocal elasticity theory, a nonclassical model is developed. Using the Galerkin method(GM), the governing equation which is a nonlinear partial differential equation(NLPDE) of the fourth order is converted to a nonlinear ordinary differential equation(NLODE) in the time domain. Then, the reduced NLODE is solved analytically by means of the homotopy analysis method. At the end, the effects of model parameters as well as the nonlocal parameter on the deflection, nonlinear frequency, and dynamic pull-in voltage are explored.  相似文献   
8.
为了揭示中墩斜支承对连续箱梁力学性能的影响,本文考虑约束扭转和竖向挠曲耦合作用,建立了斜支承连续箱梁的力法方程,并获得了内力和变形的解析式。选取斜支承两跨连续箱梁为数值算例,分别计算了竖向对称和偏心均布荷载作用下的内力和变形,并用ANSYS软件计算了控制截面的弯矩。计算结果表明,本文方法计算的弯矩与ANSYS计算值吻合良好;与常规的连续箱梁相比,在竖向对称均布荷载作用下,斜支承连续箱梁的挠度减小不显著,而在竖向偏心均布荷载作用下,斜支承连续箱梁的挠度有显著变化,斜交角为45°时,挠度改变量可达到25%以上;无论是在竖向对称还是偏心均布荷载作用下,斜支承连续箱梁的扭转角均大于常规连续箱梁的扭转角,二次扭矩和双力矩都仅在斜支承点附近的局部范围出现较大值。  相似文献   
9.
CeO2-based catalysts are widely studied in catalysis fields. Developing one novel synthetic approach to increase the intimate contact between CeO2 and secondary species is of particular importance for enhancing catalytic activities. Herein, an interfacial reaction between metal–organic framework (MOF)-derived carbon and KMnO4 to synthesize CeO2−MnO2, in which carbon is derived from the pyrolysis of Ce-MOFs under an inert atmosphere, is described. The MOF-derived carbon is found to restrain the growth of CeO2 crystallites under a high calcination temperature and, more importantly, intimate contact within CeO2/C is conveyed to CeO2/MnO2 after the interfacial reaction; this is responsible for the high catalytic activity of CeO2−MnO2 towards CO oxidation.  相似文献   
10.
The development of high-efficiency electrocatalysts with low costs for the oxygen evolution reaction (OER) is essential, but remains challenging. Herein, a new synthetic process is proposed to prepare Ni3S4 particles embedded in N,P-codoped honeycomb porous carbon aerogels (Ni3S4/N,P-HPC) through a hydrogel approach. The preparation of Ni3S4/N,P-HPC begins with the sol–gel polymerization of tripolyphosphate, chitosan, and guanidine polymer that contains metal-binding sites, allowing for the uniform incorporation of Ni ions into the gel matrix, freeze-drying, and subsequent carbonization under an inert atmosphere. This synthesis resolves difficulties in synthesizing the pure Ni3S4 phase caused by the instability of Ni3S4 at high temperature, while affording good control of the porous structure and N,P-doping of carbon aerogels. The synergy between the structural advantages of N,P-carbon aerogels (such as easily accessible active sites, high specific surface area, and excellent electron transport) and the intrinsic electrochemical properties of Ni3S4 result in the outstanding OER performance of Ni3S4/N,P-HPC, with overpotentials as low as 0.37 V at 10 mA cm−2. The work outlined herein offers a simple and effective method for the development of carbon-based electrocatalysts for renewable energy conversion.  相似文献   
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