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排序方式: 共有3383条查询结果,搜索用时 15 毫秒
991.
992.
It is shown that stable and unstable limit cycles are born at a certain value of the follower force. As the absolute value of the force increases, the cycles move with different velocities in opposite directions. The unstable limit cycle moves toward the origin in the four-dimensional phase space. At a certain value of the follower force, this cycle gets at the origin, disturbing its stability as a singular point of the dynamic system. If the absolute value of the follower force decreases, then death of both cycles is possible. In this case, the attraction domain of the origin becomes infinite 相似文献
993.
Markus Lazar 《Journal of Elasticity》2007,88(1):63-78
In this paper, following Noether’s theorem we investigate the Lie point symmetries of linear micromorphic elastodynamics (linear
elastodynamics with microstructure). Conservation and balance laws of linear, micromorphic elastodynamics are derived. We
generalize the J, L and M integrals for this theory. In addition, we give the Eshelby stress tensor, pseudomomentum vector, field intensity vector,
Hamiltonian, angular momentum tensor and scaling flux generalized to micromorphic elastodynamics.
相似文献
994.
一类高精度TVD差分格式及其应用 总被引:2,自引:0,他引:2
构造了一维非线性双曲型守恒律的一个新的高精度、高分辨率的守恒型TvD差分格式。其构造思想是:首先,将计算区间划分为若干个互不相交的小区间,再根据精度要求等分小区间,通过各细小区间上的单元平均状态变量,重构各细小区间交界面上的状态变量,并加以校正;其次,利用近似Riemann解计算细小区间交界面上的数值通量,并结合高阶Runge—Kutta TVD方法进行时间离散,得到了高精度的全离散方法。证明了该格式的TVD特性。该格式适合于使用分量形式计算而无须进行局部特征分解。通过计算几个典型的问题,验证了格式具有高精度、高分辨率且计算简单的优点。 相似文献
995.
A. A. Kaminskii 《International Applied Mechanics》2004,40(8):829-846
The laws of stable crack growth are analyzed using fracture mesomechanics models for polymeric materials under long-term subcritical tension. A review is given of experimental and theoretical studies of crack-tip process zones. The studies were conducted using physical and mechanical methods and fracture mesomechanics models, allowing for the structural and rheological features of process zones. Theoretical and experimental results on the behavior of process zones are generalized and the theory of stable crack growth in viscoelastic polymers, which assumes the autonomy of the process zone during crack development, is justified 相似文献
996.
A numerical approach for structural analysis of masonry walls in plane stress conditions is presented. The assumption of a perfectly no-tension material (NTM) constitutive model, whose relevant equations are in the form of classical rate-independent associated flow laws of elastoplastic material, allows one to adopt numerical procedures commonly used in computational plasticity. An accuracy analysis on the integration algorithm employed in the solution of constitutive relations has been carried out. The results obtained for some relevant case-studies and their comparison with data, available in the literature show the effectiveness of the proposed method.
Sommario Si presenta un approccio numerico per l'analisi strutturale di pareti in muratura in stato piano di tensione. L'assunzione di un modello costitutivo per materiale perfettamente non resistente a trazione (NTM), le cui equazioni sono esprimibili nella classica forma incrementale delle leggi dello scorrimento plastico di tipo associato per materiali elastoplastici, consente di adottare procedure numeriche comunemente utilizzate in plasticità computazionale. Si conduce un'analisi di accuratezza dell'algoritmo utilizzato nell'integrazione delle equazioni costitutive del modello esaminato. I risultati ottenuti per alcuni casi analizzati ed il confronto effettuato con esempi riportati in letteratura mostrano l'efficienza dell'approccio proposto.相似文献
997.
998.
999.
将Jin's的界面方法应用到求解双曲守恒型方程的半离散中心迎风方法中,给出了一种新的求解浅水波方程的半离散中心迎风差分方法。对于源项,不是采用传统的单元均值而是采用单元界面处的值来近似,使所得格式对稳定态的求解是均衡的。且已证明所给的二阶精度的求解格式保持水深的非负性,这一特性使其能够较好的处理干河床问题。使用该方法产生的数值粘性(与O(Δ2r-1)同阶)要比交错的中心格式小(与O(Δx2r/Δt)同阶),而且由于数值粘性与时间步长无关,从而时间步长可根据稳定性需要尽可能的小,因此适用于稳定态的求解。 相似文献
1000.
Vasilly M. Goloviznin Vladimir N. Semenov Ivan A. Korotkin Sergey A. Karabasov 《Transport in Porous Media》2007,66(3):439-456
The paper is devoted to a new computational method for problems of transport in highly non-uniform media. In particular, the
method is applied to the problem of anomalous contaminant transport in a field with a randomly distributed permeability, which
was modelled as a stochastic advection process governed by a stochastic advection model. The stochastic advection model is
used to generate different realisations of micro-dispersion parameters required for direct numerical simulations. The new
numerical method combines the merits of finite-volume and finite-difference approaches and is demonstrated to be efficient
and robust in several benchmark advection tests. For the stochastic advection problem considered the results of the new computational
method are in a good agreement with analytical predictions available for different stochastic advection regimes. 相似文献