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排序方式: 共有591条查询结果,搜索用时 9 毫秒
61.
We present a multiscale model for anisotropic, elasto-plastic, rate- and temperature-sensitive deformation of polycrystalline aggregates to large plastic strains. The model accounts for a dislocation-based hardening law for multiple slip modes and links a single-crystal to a polycrystalline response using a crystal plasticity finite element based homogenization. It is capable of predicting local stress and strain fields based on evolving microstructure including the explicit evolution of dislocation density and crystallographic grain reorientation. We apply the model to simulate monotonic mechanical response of a hexagonal close-packed metal, zirconium (Zr), and a body-centered cubic metal, niobium (Nb), and study the texture evolution and deformation mechanisms in a two-phase Zr/Nb layered composite under severe plastic deformation. The model predicts well the texture in both co-deforming phases to very large plastic strains. In addition, it offers insights into the active slip systems underlying texture evolution, indicating that the observed textures develop by a combination of prismatic, pyramidal, and anomalous basal slip in Zr and primarily {110}〈111〉 slip and secondly {112}〈111〉 slip in Nb. 相似文献
62.
考虑辊系倾角的轴移式轧机辊系弹性变形计算 总被引:1,自引:1,他引:0
采用分段离散法 ,求解轴移式轧机辊系弹性变形 ,其方法主要特点是计算过程中考虑了轴移式轧机由于工作辊的窜动而引起的辊系倾角对辊系变形挠度的影响 ,为藕合计算板凸度时提供更为合理的辊系弹性变形模型。 相似文献
63.
对扭转多线切分轧制的斜配孔型进行了一定的孔型设计和实验研究,较为详细地介绍了孔型设计、斜配角度、坯料选择、对比轧制实验时的结果分析、轧制原理等一系列问题。 相似文献
64.
C. -A. Peng L. A. Jurman M. J. McCready 《International Journal of Multiphase Flow》1991,17(6):767-782
The origin of solitary waves on gas-liquid sheared layers is studied by comparing the behavior of the wave field at sufficiently low liquid Reynolds number, RL, where solitary waves are observed to form, to measurements at higher RL where solitary waves do not occur. Observations of the wave field with high-speed video imaging suggest that solitary waves, which appear as a secondary transition of the stratified gas-liquid interface, emanate from existing dominant waves, but that not all dominant waves are transformed. From measurements of interface tracings it is found that for low RL, waves which have amplitude/substrate depth (a/h) ratios of 0.5–1 occur while for higher RL, no such waves are observed. A comparison of amplitude/wavelength ratios shows no distinction for different RL. Consequently, it is conjectured that solitary waves originate from waves with sufficiently large a/h ratios; this change of form being similar to wave breaking. The dimensionless wavenumber is found to be smaller at low RL, where solitary waves are observed. This suggests that perhaps, larger precursor (to solitary wave) waves are possible because the degree of dispersion, which acts to break waves into separate modes, is lower. 相似文献
65.
何江川 《华侨大学学报(自然科学版)》1994,15(1):80-84
介绍自由分度式冷轧法轧制牵伸罗拉沟槽齿形的特点,设计和制造齿形轧轮的简易方法,适合于中小企业生产和开发. 相似文献
66.
A. Mielke 《Journal of Nonlinear Science》1997,7(1):57-99
Summary We introduce a new method for the analysis of sideband instabilities which are important for periodic patterns appearing in
systems close to the instability threshold. The method relies on a two-fold application of the Liapunov-Schmidt reduction
procedure, a first application to the nonlinear bifurcation problem and a second application to the linear spectral problem.
We obtain rigorous results on the spectrum of the associated linearization in spaces allowing for general sideband perturbations
by treating the sideband vector and the spectral parameter as small bifurcation parameters.
We apply the theory to the small roll solutions in the Rayleigh-Bénard convection and derive domains in Rayleigh, Prandtl,
and wave number space where the rolls are unstable. We recover the Eckhaus, zigzag, and skew-varicose instabilities obtained
earlier by formal methods.
This paper is dedicated to the memory of Juan C. Simo
This paper was solicited by the editors to be part of a volume dedicated to the memory of Juan C. Simo. 相似文献
67.
K. N. Gavrilova 《Journal of Applied Mechanics and Technical Physics》2004,45(1):37-44
A hyperbolic model of a shallow water flow is considered with allowance for nonlinear and dispersion effects. The structure of traveling waves above a flat bottom is studied. Stability of small disturbances of a homogeneous flow and development of instability of a nonstationary flow above an inclined bottom are analyzed. 相似文献
68.
69.
装药结构对传爆药柱起爆能力的影响研究 总被引:3,自引:0,他引:3
为了适应钝感弹药对传爆序列提出的新要求,根据炸药冲击起爆理论,研究了凹球形和半球形两种新结构传爆药柱,并对两种新结构传爆药柱与普通圆柱形传爆药柱的起爆威力进行了实验对比.研究结果表明,改变传爆药柱的结构可提高其输出威力,新结构传爆药柱较普通圆柱形传爆药柱的起爆威力有明显提高.研究结果对解决钝感弹药的可靠起爆问题具有重要意义. 相似文献
70.
讨论了利用SIEMENS6RA70系列直流传动控制器的主从控制模式解决中板生产线上双边剪夹送辊传动系统的速度同步和负荷均衡问题的方法。采用该方法,可以有效地防止剪切过程中出现钢板跑偏及负荷不平衡等现象,从而大大降低故障时间,提高生产率。 相似文献