谈运动学中的两个基本定义

讨论了点的牵连运动与刚体的定轴转动的定义, 并就这两个定义的科学性进行了阐述, 给出了一个建议.     

火灾后钢筋混凝土异形板的极限均布荷载

本文基于塑性铰线理论确定了钢筋混凝土异形板的破坏机构，并利用有限差分法计算了火灾时板内的温度场，根据高温后钢筋和混凝土的力学性能对塑性铰线截面的弯矩及灾后极限均布荷载进行了分析，为钢筋混凝土板火灾后的评估和维修提供依据．     

扇形截面杆扭转问题的差分线法

导出了扇形截面杆扭转问题偏微分方程的差分线法常微分方程组, 并解析求解了该方程组, 得到了扭转应力函数的半解析解, 计算了扭转应力及扭转刚度. 计算过程中, 用追赶法计算 常微分方程组的特解, 用公式计算三对角矩阵的特征值与特征向量, 利用实对阵矩阵的特征 向量相互正交的特性避免矩阵求逆计算, 利用复化梯形公式计算扭转刚度. 整个求解过程在 角度方向离散微分方程和用复化梯形公式进行面积积分时引入了误差, 其他求解过程是精确 的. 计算结果与已有结果进行了对比, 显示了算法的正确性. 该算法对工程中扇形截面扭 转杆的设计有一定的实用价值.     

提高能量法确定压杆临界荷载精度的一种方法

通过杆件的弯矩位移关系消去能量法确定压杆临界荷载公式中的位移导数项,大大地提高了其计算精度,文后给出的两个算例证明了这一结论.     

弹性悬链线方程参数变换法及其工程应用

建立了弹性锚泊线模型,该模型根据微段垂向力学平衡关系,通过引进一个变换参数$u$(${\rm sinh} u=\d y/\d x$),得到了弹性悬链线的参数方程. 结合工程实际,将该模型用于海洋工程中的锚泊线,给出锚泊线拉力公式,与求解算法. 该算法简单有效,易于编程实现.     

漫谈热胀冷缩的``功''与``过''

 热胀冷缩现象在我们周围随处可见，只有更好地掌握它的规律，才能避免或减小它的危害， 利用它为人类造福.     

持久极限简化折线与构件的持久极限

非对称循环下构件的持久极限点的选取, 现行不同的教科书的论述多含糊不清甚至有误, 本文给出较为明确的选取方法.     

三铰拱弯矩影响线的图解法

介绍了三铰拱弯矩影响线的一种图解方法, 并给出了完整的证明.     

带弹簧支撑超静定结构位移的简化计算方法

针对带有弹性支撑的超静定结构的位移计算问题, 对利用虚功原理得到的位移计算一般公式进行了进一步推导, 提出了该类结构位移的简化计算方法. 文中计算公式表达形式简洁, 且与一般刚性支撑超静定结构的位移计算方法一致. 通过与有限元分析结果的对比,证明了该公式的正确性.     

最速降线问题解充分性的证明

利用可动边界的变分公式,通过广义环路积分导出Hilbert不变积分,在此基础上说明了最速降线问题解的充分性.     

Enhanced model of load distribution along the line of contact for non-standard involute external gears

The presence of undercut at the tooth root, non-equal addendum on pinion and wheel, non-standard tooth height or non-standard center distance may have decisive influence on the load distribution along the line of contact of spur and helical gear teeth. The curve of variation of the meshing stiffness along the path of contact, quite symmetric respect the midpoint of the interval of contact, loses its symmetry for non-standard geometries and operating conditions. As a consequence, the critical contact points for bending and wear calculations may be shifted from their locations for standard gears. In this paper, a non-uniform model of load distribution along the line of contact of standard spur and helical gears, obtained from the minimum elastic potential criterion, has been enhanced to fit with the meshing conditions of the above mentioned non-standard cylindrical gear pairs. The same analytical formulation of the initial model may be used for the non-standard gears by considering appropriate values of a virtual contact ratio, which are also presented in the paper.     

The simplified buckling criterion applied to plates with partial edge loading

The development is outlined of the first author's Simplified Plate Buckling Criterion which is based on nonlinear theory. For the case of uniaxial, symmetric, partial-edge loading, the work of the first author is compared with the numerical solutions of the second author and with the results of Yamaki by energy theory. The Simplified Criterion gives results with a minimum of computational effort well within practical accuracy requirements.

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Zusammenfassung Die Ableitung des auf nichtlineare Theorie begründeten vereinfachten Plattenbeulungskriterium des ersten Verfassers ist skizziert. Für den Fall der einachsig, symmetrisch, teilweis belagerten Platte werden die Ergebnisse des ersten Verfasser mit den rein numerischen Ergebnissen des zweiten Verfasser und mit dem auf Energietheorie begründeten Ergebnissen Yamakis verglichen. Mit sehr minimaler Rechnungsbemühung kann das vereinfachte Plattenbeulungskriterium Koeffiziente erzielen deren Exaktheit innerhalb der üblichen Sicherheitsgrenze liegt.

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Based in part on a paper presented to the 19th Midwestern Mechanics Conference, Ohio State University, Columbus, Ohio, Sept. 9–11, 1985.     

The calculation of free electron density in Cassandra

Cassandra is an AWE opacity code used to model plasmas in local thermal equilibrium: there is a desire to expand its use to calculating plasma equations of state. Cassandra's self-consistent field calculation (scf) uses the local density approximation for bounds states and has a free electron contribution based upon the Thomas-Fermi model [B.J.B. Crowley et al., J. Quant. Spectro. Radiat. Trans. 71, 257(2001)]. Whilst this is applicable for very high temperature or low density plasmas; in hot and dense matter the effect of ionization will lead to discontinuities in the effective ionisation, Z^?. The electron contribution to hydrostatic pressure is associated with Z^?, thus these discontinuities produce unphysical jumps in the resulting calculated material pressure.We describe a procedure to mitigate the effect by calculating the free electron wave functions within the generalized ion-cell model [B.J.B. Crowley et al., Phys. Rev. A 41, 2179(1990)], and thus explicitly calculate free-electron resonances.     

土质边坡极限荷载上限计算方法研究

以边坡极限分析的上限解析式为标准,在无重力情况下利用不同屈服准则的数值方法计算了相同工况下边坡的极限荷载。针对一个实际边坡工况使用解析和FLAC方法计算了边坡的极限荷载上限,并且基于强度折减法使用FLAC确定了各种荷载下边坡的安全系数。通过与解析方法计算结果的比较发现,基于Mohr-Coulomb准则的FLAC软件计算出的边坡极限荷载更加接近解析解。不同边坡顶角或不同内摩擦角的计算结果显示FLAC计算出的边坡极限荷均稍大于解析解,并且内摩擦角越大差值越大,但两者的差别最大不超过5%。     

A note on the maximum number and density of distribution of members in elastic structures of minimum weight under multiple loading conditions

The problem of minimum weight design of elastic structures under multiple loading conditions is considered. It is shown that the problem can be expressed as a search for feasible deflection patterns coupled with repeated searches for structures of minimum weight for given stiffness. The latter is a Linear Programming Problem and implies an upper limit, different from that set by connectivity, on both the number and distribution density of elements present in the minimum weight design.     

表面裂纹准静态扩展的有限元模拟计算

由于现有断裂准则未能考虑表面裂纹前沿各点实际断裂阻力的变化，所作的表面裂纹准静态扩展模拟计算不能很好地预测几何形貌的真实变化规律。本文提出了一个考虑应力状态不同对实际断裂阻力影响的变阻力断裂准则；并以该准则作为表面裂纹前沿局部断裂扩展的判据，通过三维有限元法进行了表面裂纹准静态扩展的模拟计算；还将模拟预测值与用多试件法测得的实验值进行比较，验证了变阻力断裂准则作为裂纹稳态扩展判据的有效性     

The calculation of the density field from axisymmetric schlieren interferograms by the image processing techniques

The schlieren interferograms used to be analyzed in a qualitative way. In this paper, by means of the powerful computational ability and the large memory of computer; the image processing method is investigated for the digitalization of an axisymmetric schlieren interferogram and the determination of the density field. This method includes the 2-D low-pass filtering, the thinning of interferometric fringes, the extraction of physical information and the numerical integration of the density field. The image processing results show that the accuracy of the quantitative analysis of the schlieren interferogram can be improved and a lot of time can be saved in dealing with optical experimental results. Therefore, the algorithm used here is useful and efficient.