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41.
A solution is found to a plane problem for a composite material reinforced with two in-line fibers and subjected to longitudinal compression. The problem formulation is based on the piecewise-homogeneous model and the three-dimensional theory of stability. The dependence of the critical strain and buckling mode on the distance between the fibers is studied for various mechanical and geometrical characteristics of the composite components.Translated from Prikladnaya Mekhanika, Vol. 40, No. 9, pp. 65–74, September 2004. 相似文献
42.
A direct central collision of two identical infinite cylindrical bodies is studied. A nonstationary plane elastic problem is solved. The variable boundary of the contact area is determined. A mixed boundary problem is formulated. Its solution is represented by Fourier series. An infinite system of Volterra equations of the second kind for the unknown expansion coefficients is derived by satisfying boundary conditions. The basic characteristics of the collision process are determined numerically depending on the curvature of the frontal surface of the bodies 相似文献
43.
Li-Chun Bian Zouheir Fawaz Kamran Behdinan 《Archive of Applied Mechanics (Ingenieur Archiv)》2007,77(11):809-821
The maximum energy release rate criterion, i.e., G
max
criterion, is commonly used for crack propagation analysis. This fracture criterion is based on the elastic macroscopic strength
of materials. In the present investigation, however, the G
max
criterion has been modified in order to accommodate the consideration of plastic strain energy. This modified criterion is
extended to study the fatigue crack growth characteristics of mixed-mode cracks. To predict crack propagation due to fatigue
loads, a new elasto–plastic energy model is presented. This new model includes the effects of material properties such as
strain hardening exponent n, yield strength σ
y
, and fracture toughness and stress intensity factor ranges. The results obtained are compared with those obtained using the
commonly employed crack growth law and the experimental data. 相似文献
44.
单相旋转型驻波超声电机的数学模型及仿真 总被引:1,自引:0,他引:1
尽管单相驱动的旋转型驻波超声电机的原理样机早巳研制成功,但对这类电机的运动机理的研究却一直局限在定性分析上。本文将从能量角度,根据Hamilton变分原理,定、转子摩擦界面采用纯滑动模型建立了该种电机的数学模型;并根据此模型,用MATLAB语言作了计算机仿真,得到了该种电机的开、关过程动态响应。 相似文献
45.
For the N-degree-of-freedom of linear conservative vibratory systems, the corresponding potential functions can be viewed as N-hypersurfaces in (N + 1)-dimensional space. In this paper, a connection between the geometrical properties (principal curvatures, curvature lines) of potential surfaces and the vibratory characteristics (natural frequencies, linear modes) of the system is built. It is proved that the linear normal modes are exactly the projections of the lines of curvature on the potential surface onto the configuration space with metric mij (the mass-matrix); and that the squared natural frequencies are exactly the principal curvatures, at the origin of the configuration space, of the potential surface. 相似文献
46.
47.
运用复模态理论对考虑海洋平台结构与流体相互作用而引起的非经典阻尼问题进行了理论分析。水中耦合阻尼矩阵运用复模态解法,可以不必近似对角化。推导了随机波浪荷载作用下结构各种反应的能量谱密度函数及结构反应的统计特性,得到了结构反应的均方差和峰值的表达式。针对某典型平台在随机波浪荷载作用下动力反应用复模态法进行了计算并与运用实模态方法多重叠代方法的结果进行了比较。 相似文献
48.
Some basic concepts about the active structures were firstly explained, and the main subjects to study in the field of active structure dynamics were synthesized. For the linear active structures, the annotations on the modes were done in detail. The physical meanings of the right and left eigenvectors were explained. The right eigenvectors are the modal shapes and the modal responses of an active structure depend on the left ones. The adjoint structure of an active structure was defined and the reciprocity theorem was interpreted. For two active structures, which are adjoint to each other and with the reciprocal gain-matrices, the right and left eigenvector are reciprocal. The relationship between an active structure and the corresponding passive structure is expressed with the transfer functions, which is employed to resolve the estimation problems. 相似文献
49.
In this paper the analytical solutions of the impact of a particle on Timoshenko beams with four kinds of different boundary
conditions are obtained according to Navier's idea, which is further developed. The initial values of the impact forces are
exactly determined by the momentum conservation law. The propagation of the longitudinal and transverse waves along the beam,
especially, the effects of boundary conditions on the characteristics of the reflected waves, are investigated in detail.
Some results are compared with those by MSC/NASTRAN. 相似文献
50.
粘性可压混合层时间稳定性对称紧致差分求解 总被引:2,自引:0,他引:2
基于可压扰动方程组的一阶改型 ,将高精度对称紧致格式引入边值法数值线性稳定性分析。对所获非线性离散特征值问题给出了一个通用形式二阶迭代局部算法 ,实现了时间模式和空间模式的统一求解 ,并将扰动特征值及其特征函数同时得到。据此分析了可压平面自由混合层时间稳定性 ,涉及二维 /三维扰动波、粘性 /无粘扰动波、第一 /第二模态、特征函数、伪特征值谱等。研究表明 ,压缩性效应和粘性效应对最不稳定扰动波数和增长率呈相似的减抑作用 ;在 Mc=1附近 ,从高波数段开始 ,粘性效应可强化二维不稳定扰动波由第一模态向第二模态的过渡 相似文献