正高斯双曲空腹扁网壳连续化模型的等效刚度

对由正交拱架组成的正高斯双曲空腹扁网壳进行分析,探讨了基于连续化计算模型的拟壳分析法,给出正高斯双曲空腹扁网壳的等代薄膜刚度和弯曲刚度的表达式,按弹性小挠度薄壳理论进行分析,建立了正高斯双曲空腹扁网壳的基本方程式。

铝合金蜂窝板-杆组合网格结构的等效刚度研究

铝合金蜂窝板作为典型的轻质高强材料已被广泛应用于航空航天领域。由于大跨空间结构对自重特别敏感,为此将蜂窝板与单层铝合金网壳可靠连接,形成一种新型组合网壳,前期研究结果表明,该结构显著提高了单层铝合金网壳的整体刚度及稳定性。为探究蜂窝板与铝合金杆之间共同工作的性能,以及该类组合结构的简化计算方法,设计制作了3组铝合金蜂窝板-杆组合网格结构试件开展承载力试验,并建立精细化有限元模型,进行了弹塑性分析,最后在理论分析的基础上提出了等效抗弯刚度及等效薄膜刚度的计算公式。

静水压力下圆柱壳结构屈曲机理分析

针对静水压力下圆柱壳结构的屈曲机理问题,将圆柱壳的结构刚度分为薄膜刚度和弯曲刚度,分析了具有完整刚度下圆柱壳的失稳压力,并与已有的理论进行了比较,验证了方法的可靠性。通过消除圆柱壳结构各部分薄膜刚度获得了消除刚度后的临界屈曲载荷,分析了各部分薄膜刚度对静水压力下圆柱壳承载能力的影响,结果表明,静水压力下圆柱壳屈曲的原因是结构周向薄膜刚度的减少。

Electrochemical oxidation of reactive brilliant orange X-GN dye on boron-doped diamond anode

In this study,the electrochemical oxidation of reactive brilliant orange X-GN dye with a boron-doped diamond(BDD)anode was investigated.The BDD electrodes were deposited on the niobium(Nb)substrates by the hot filament chemical vapor deposition method.The effects of processing parameters,such as film thickness,current density,supporting electrolyte concentration,initial solution pH,solution temperature,and initial dye concentration,were evaluated following the variation in the degradation efficiency.The microstructure and the electrochemical property of BDD were characterized by scanning electron microscopy,Raman spectroscopy,and electrochemical workstation;and the degradation of X-GN was estimated using UV-Vis spectrophotometry.Further,the results indicated that the film thickness of BDD had a significant impact on the electrolysis of X-GN.After 3 h of treatment,100%color and 63.2%total organic carbon removal was achieved under optimized experimental conditions:current density of 100 mA/cm2,supporting electrolyte concentration of 0.05 mol/L,initial solution pH 3.08,and solution temperature of 60°C.

Effect of deposition temperature on properties of boron-doped diamond films on tungsten carbide substrate

Boron-doped diamond(BDD)films were deposited on the tungsten carbide substrates at different substrate temperatures ranging from 450 to 850°C by hot filament chemical vapor deposition(HFCVD)method.The effect of deposition temperature on the properties of the boron-doped diamond films on tungsten carbide substrate was investigated.It is found that boron doping obviously enhances the growth rate of diamond films.A relatively high growth rate of 544 nm/h was obtained for the BDD film deposited on the tungsten carbide at 650°C.The added boron-containing precursor gas apparently reduced activation energy of film growth to be 53.1 kJ/mol,thus accelerated the rate of deposition chemical reaction.Moreover,Raman and XRD analysis showed that heavy boron doping(750 and 850°C)deteriorated the diamond crystallinity and produced a high defect density in the BDD films.Overall,600-700°C is found to be an optimum substrate temperature range for depositing BDD films on tungsten carbide substrate.

Reinforcement by polyurethane to stiffness of air-supported fabric formwork for concrete shell construction

By spraying concrete on inner surface,air-supported fabric structures can be used as formwork to construct reinforced concrete shell structures.The fabric formwork has the finished form of concrete structure.Large deviation from the desired shape of concrete shells still remains as central problem due to dead weight of concrete and less stiffness of fabric formwork.Polyurethane can be used not only as a bonding layer between fabrics and concrete but also as an additional stiffening layer.However,there is little research on mechanical behaviors of the polyurethane shell structure.This paper presents experimental studies on an inflated fabric model with and without polyurethane,including relief pressure tests,vertical loading tests and horizontal loading tests.Experimental results show that the additional polyurethane layer can significantly enhance the stiffness of the fabric formwork.Compared with the experiment,a numerical model using shell layered finite elements has a good prediction.The reinforcement by polyurethane to improve stiffness of air-supported fabric formwork is expected to be considered in the design and construction of the concrete shell,especially dealing with the advance of shape-control.

Visible photoluminescence from ZnO/diamond-like carbon thin films

ZnO/diamond-like carbon (DLC) thin films are deposited by pulsed laser deposition (PLD) on Si (111) wafer. Visible room-temperature photoluminescence (PL) is observed from ZnO/DLC thin films by fluorescence spectrophotometer. The Gaussian curve fitting of PL spectra reveals that the broadband visible emission contains three components with λ=508 nm, 554 nm and 698 nm. The origin and possible mechanism of the visible PL are discussed, and they can be attributed to the PL recombination of ZnO and DLC thin films.