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991.
铝材轧制过程中润滑添加剂吸附特性研究 总被引:3,自引:5,他引:3
依据铝材轧制过程中润滑油添加剂浓度对摩擦因数的影响,同时以Temkin吸附理论为基础,设定添加剂分子在摩擦表面的覆盖率与摩擦因数的联系,提出了铝材轧制过程中润滑添加剂吸附有的求解方法,还定义了铝材轧制时润滑添加剂饱和吸附最低浓度的概念,通过二辊轧机测定了在不同添加剂浓度时纯铝材轧制过程中的摩擦因数,并且计算了相应的润滑添加剂的吸附自由能及其饱和吸附最低浓度,表明理论分析结果与实测结果具有良好的一致 相似文献
992.
Francesco Sorge 《Meccanica》1995,30(1):37-52
Turbocompressor surge in a line with a long suction duct and plenum chamber is analysed using a distributed parameter propagation model which accounts for dynamic damping. The results, though obtained with simplifying assumptions, show very good agreement with experimental data.
Sommario Si studia il pompaggio di un turbocompressore centrifugo con lungo condotto di aspirazione e volume di raccolta alla mandata, adoperando un modello a parametri distribuiti ove si considera lo smorzamento dinamico ad opera dello strato limite di parete. L'accordo tra previsioni teoriche e dati sperimentali è ottimo, nonostante le semplificazioni introdotte.相似文献
993.
本文根据修正势能原理通过广义协调方法提出了一种列式简单的平板型矩形壳元GCR24。它在四个角点处各有六个自由度,总共二十四个自由度。作为一种极限协调元,单元的收敛性得到保证,并且不发生薄膜闭锁现象。通过标准问题的数值检验,表明本文提出的平板型矩形薄壳元是性能可靠、计算精度高的优质单元。 相似文献
994.
995.
Effect of alkali metal ions on the viscoelasticity of concentrated kappa-carrageenan and agarose gels 总被引:1,自引:0,他引:1
The effect of the addition of the monovalent cations Li+, Na+, K+, and Cs+ on the gelation of agarose and kappa-carrageenan aqueous gels has been studied by the measurement of longitudinal vibration. The dynamic Youngs's modulusE of 2% w/w agarose and 0.4–6% w/w kappa-carrageenan gels containing the alkali metal salt LiCl, NaCl, KCl or CsCl of various concentrations from 0 to 4.5 mol/l has been measured at various temperatures. By the addition of the alkali metal salt, the value ofE for agarose gels is influenced only slightly, while for kappa-carrageenanE is increased substantially. Kappa-carrageenan has many sulphate groups. The addition of the alkali metal ions screens the electrostatic repulsion between these groups. As a result of this, the helical structure of kappa-carrageenan is stabilised and the helices may form densely packed aggregates, so increasingE. In contrast, agarose has a naturally stable molecular structure and therefore, the structure and henceE is not sensitive to added ions. The K+ and Cs+ ions increaseE more than Li+ and Na+ for kappa-carrageenan gels. This is interpreted on the basis that these ions are either structure ordering or structure disordering ions for water. 相似文献
996.
本文就薄板后屈曲问题建立一组新型的边界元计算公式,用这组公式求解能方便处理各种边界问题,另外文中将面内应力分解成基本部份和附加部份,并利用微分算子分解理论导得了挠度的一个不同形式的基本解,由于计算公式中,实现了面内位移和挠度的解耦,从而使迭代过程得到简化,文末还对圆板后屈曲路径进行了计算,得到了满意的结果。 相似文献
997.
悬索在考虑1:3内共振情况下的动力学行为 总被引:2,自引:0,他引:2
研究了悬索在受到外激励作用下考虑1∶3内共振情况下的两模态非线性响应.对于一定范围内悬索的弹性-几何参数而言,悬索的第三阶面内对称模态的固有频率接近于第一阶面内对称模态固有频率的三倍,从而导致1∶3内共振的存在.首先利用Galerkin方法把悬索的面内运动方程进行离散,然后利用多尺度法对离散的运动方程进行摄动得到主共振情况下的平均方程.接下来对平均方程的稳态解、周期解以及混沌解进行了研究.最后利用Runge-Kutta法研究了悬索两自由度离散模型的非线性响应. 相似文献
998.
A generalized finite spectral method is proposed. The method is of high-order accuracy. To attain high accuracy in time discretization, the fourth-order Adams-Bashforth-Moulton predictor and corrector scheme was used. To avoid numerical oscillations caused by the dispersion term in the KdV equation, two numerical techniques were introduced to improve the numerical stability. The Legendre, Chebyshev and Her-mite polynomials were used as the basis functions. The proposed numerical scheme is validated by applications to the Burgers equation (nonlinear convection- diffusion problem) and KdV equation (single solitary and 2-solitary wave problems), where analytical solutions are available for comparison. Numerical results agree very well with the corresponding analytical solutions in all cases. 相似文献
999.
1000.
Nix and Gao established an important relation between the microindentation hardness and indentation depth. Such a relation
has been verified by many microindentation experiments (indentation depths in the micrometer range), but it does not always
hold in nanoindentation experiments (indentation depths approaching the nanometer range). Indenter tip radius effect has been
proposed by Qu et al. and others as possibly the main factor that causes the deviation from Nix and Gao's relationship. We
have developed an indentation model for micro- and nanoindentation, which accounts for two indenter shapes, a sharp, conical
indenter and a conical indenter with a spherical tip. The analysis is based on the conventional theory of mechanism-based
strain gradient plasticity established from the Taylor dislocation model to account for the effect of geometrically necessary
dislocations. The comparison between numerical result and Feng and Nix's experimental data shows that the indenter tip radius
effect indeed causes the deviation from Nix-Gao relation, but it seems not be the main factor.
The project supported by the National Natural Science Foundation of China (10121202) and the Ministry of Education of China
(20020003023) 相似文献