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991.
轴对称冲击有限元一致质量矩阵迭代解 总被引:1,自引:0,他引:1
给出高速冲击动力有限元一致质量矩阵解的迭代过程,即把集总质量矩阵解作为初值进行有限次迭代得到满足工程需要的一致质量矩阵近似解.实际算例说明,一致质量近似解较集总质量解改善了对应力波传播过程的分析,而且在高速冲击计算中能给出与实验接近的计算结果. 相似文献
992.
报导了简支、固支方形管状截面铝合金梁在子弹撞击时动力响应的实验研究。实验中,采用电-光位移传感器记录了梁中点的位移-时间、速度-时间和加速度-时间历史曲线。实验结果表明,在子弹动能相同、质量不同时,其变形不同。梁中点最大位移和中点最终位移间有较大的差值,可见采用理想刚塑性模型很难描述这一现象,在分析中,必须考虑弹性效应。同时发现,由于方管局部变形而引起的变形软化效应将减少梁的动力承载能力。 相似文献
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995.
I. V. Shevchuk 《Fluid Dynamics》2003,38(1):18-27
An exact solution of the heat transfer problem for a uniform air stream impinging on a rotating disk is found. By introducing self-similar radial velocity and temperature profiles, the problem is reduced to a system of ordinary differential equations which are solved numerically. The Nusselt numbers are calculated for Prandtl numbers equal to 1 and 0.71 and various ratios of the free-stream velocity to the disk rotation velocity. The limits of the flow regime in which the heat transfer is determined solely by the impact jet parameters are found. The results are compared with experimental data for the stagnation point. 相似文献
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997.
The paper presents a detailed experimental study of an oblique-impact vibration system of two degrees of freedom. The primary
objective of the study is to verify the hypothesis of instantaneous impact in the oblique-impact process of two elastic bodies
such that the incremental impulse method works for computing the nonlinear dynamics of the oblique-impact vibrating systems.
The experimental setup designed for the objective consists of a harmonically excited oscillator and a pendulum, which obliquely
impacts the oscillator. In the study, the dynamic equation of the experimental setup was established first, and then the system
dynamics was numerically simulated by virtue of the incremental impulse method. Afterwards, rich dynamic phenomena, such as
the periodic vibro-impacts, chaotic vibro-impacts and typical bifurcations, were observed in a series of experiments. The
comparison between the experimental results and the numerical simulations indicates that the incremental impulse method is
reasonable and successful to describe the dynamics during an oblique-impact process of two elastic bodies. The study also
shows the limitation of the hypothesis of instantaneous impact in an oblique-impact process. That is, the hypothesis only
holds true in the case when the impact angle is not too large and the relative approaching velocity in the normal direction
is not too low. Furthermore, the paper gives the analysis of the tangential rigid-body slip on the contact surface in the
case of a large impact angle, and explains why there exist some discrepancies between the numerical simulations and the experimental
results. 相似文献
998.
Modeling an impact event is often related to the desired outcome of an impact oscillator study. If the only intent is to study
the dynamic behavior of the system, numerous researchers have shown that simpler impact models will often suffice. However,
when the geometric contours and material properties of the two colliding surfaces are known, it is often of interest to model
the contact event at a greater level of complexity. This paper investigates the application of a finite time impact model
to the study of a parametrically excited planar pendulum subjected to a motion-dependent discontinuity. Experimental and numerical
studies demonstrate the presence of multiple periodic attractors, subharmonics, quasi-periodic motions, and chaotic oscillations. 相似文献
999.
针对外边界支承的团支和简支环板,应用广义阶梯函数给出了环板在局部线性分布荷载作用下的极限荷载的计算公式。 相似文献
1000.
在交错网格中用MAC方法求解二维不可压N S方程 ,对圆截面液柱与固壁、液面斜撞击问题进行了数值模拟 ,得到了自由面随时间演化的图像。主要考察了 :(1)固壁和液面 ;(2 )牛顿、非牛顿流体 ;(3)碰撞入射角 ;(4 )Bingham流体近似本构式中参数q0 、K对计算结果的影响。结果表明 :液柱与液面碰撞形成的自由面更复杂。碰撞初期 ,Bingham流体和水的自由面相似 ;但碰撞后期 ,Bingham流体的自由面相对简单。对液柱与液面碰撞自由面的影响较大。本文条件下 ,当K 2 0时 ,K对自由面的影响不大 ;当q0 增大时 ,自由面变得相对简单。 相似文献