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圆柱面绕任意轴回转形成的包络面分析 总被引:1,自引:1,他引:0
在分析及计算椭圆上距离任意已知点最远或最近的点基础上,分析了最远点及最近点在圆柱面绕任意轴回转形成包络面过程中的作用,从而由最远点及最近点的计算公式导出了多种形式的包络面方程,并由此找出了包络面受各种因素影响的规律. 相似文献
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本文利用动态位移的回转周期变化规律,将变厚度圆板弯曲振动的二维问题化为一维形式.并将环形单元的位移函数以频率的升幂形式展开,作为动态形状函数,进而推导了动态环形元的质量和刚度矩阵及其一次动态修正矩阵,并以简洁的形式给出.最后作为本文方法的直接应用,计算了叶盘组合件的固有特性与实验值及其它方法进行了比较,说明动态的变厚度环板元的优越性. 相似文献
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为了对回转切削钻机凿岩速度进行预测,采用BP神经网络方法,对胜利露天矿钻机的钻进参数进行分析,选择钻进参数中的轴压、转速、回转压力作为BP神经网络模型的基本特征量,建立了回转切削钻机凿岩速度的BP神经网络模型.研究结果表明:凿岩速度的BP神经网络模型具有极强的非线性逼近能力,预测结果均达到预期要求,具有良好的泛化能力,能真实地反映出凿岩速度与特征量间的复杂非线性关系. 相似文献
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为研究影响回转切削钻机凿岩速度的因素的主次关系以进一步提高钻机的工作效率,在内蒙某露天矿穿孔爆破施工现场进行现场对钻机工作时的数据进行采集,运用灰关联分析理论,并且采用DPS和MATLAB7.0对试验数据进行统计和分析,得出了影响回转切削钻机凿岩速度各因素的主次关系.试验结果表明,影响钻机凿岩速度的主次关系为轴压、扭距、回转速度、岩石硬度;因此合理钻进参数的选取对提高钻机工作效率有显著的影响和重要作用. 相似文献
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根据介质的力学性能,正如Cowin及Nunziato一样,导出多孔弹性层覆盖在多孔弹性半空间上时,研究其刚性边界对扭转表面波传播的影响.导出了速度方程并对其结果进行了讨论.发现介质中可能存在两类扭转表面波阵面,而Dey等(Tamkang Journal of Science and Engineering,2003,6(4):241-249.)给出的没有刚性边界面时,存在3类扭转表面波阵面.研究还揭示,多孔弹性层中Love波也可能随同扭转表面波一起存在.值得注意的是,刚性边界面多孔弹性层中Love波的相速度,不同于自由边界面多孔弹性层中的相速度.实际观察到扭转波的色散性,以及速度随着振荡频率的增大而减小. 相似文献
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《数学的实践与认识》2020,(17)
塔机消摆控制系统是一个非线性、强耦合的复杂系统,传统PID控制效果往往欠佳.对此,建立了一个含阻尼的塔机偏摆系统数学模型,并提出模糊自抗扰控制策略.通过自抗扰控制器对塔机回转与变幅运动进行解耦,模糊算法对自抗扰控制器各参数实施在线调整,并对解耦后的回转、变幅子系统分别进行控制.在仿真实验中,对比其他典型方法,提出的方法摆角消失速度更快,这表明在负载运动过程中,所设计控制器实时性和鲁棒性较好. 相似文献
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We characterize all of the ways to represent the wheel matroids and whirl matroids using frame matroids of signed graphs. The characterization of wheels is in terms of topological duality in the projective plane and the characterization of whirls is in terms of topological duality in the annulus. 相似文献
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Normally rotor unbalance causes synchronous forward whirl of rotor‐stator systems, even if rub occurs due to rotorstatorcontact. This synchronous forward whirl has to be stable in order to avoid destructive self‐excited dry friction backward whirl, chaotic motions or sub‐ and superharmonic vibrations. However, friction between rotor and stator can cause the synchronous forward whirl to become unstable within certain rotor speed ranges. In the present paper the stability of the synchronous forward whirl caused by unbalance is investigated for rotor motions under contact with the stator. To analyse the stability of synchronous forward whirl the equations of motion are linearised around the stationary synchronous motion. The characteristic polynomial of the perturbations is calculated and the stability is checked by the Hurwitz criterion. 相似文献
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In this paper, the whirl characteristics of a flexible liquid-filled rotor subjected to thermal shock are investigated. On the basis of the Hamilton principle, the whirl frequency equation of the rotor system is derived. Using Laplace transform, the analytical model of the temperature field of the rotor is obtained. The validity of the developed temperature model is demonstrated by comparing with the finite element results. Then, the thermal axial force exerted on the rotor is calculated and the influence factors are studied. The system stability is analyzed in terms of the whirl frequency equation. The reasonability of the predict model for system stability is verified, and a good agreement can be seen in the comparison of the obtained results based on the presented analytical method with published data. Finally, the critical spinning speed of the rotor system is analyzed, and the effects of some main parameters on system critical speed are investigated. 相似文献
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Robert G. Payton 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1995,46(2):282-288
An unbounded, transversely isotropic, elastic solid, is subjected to a dislocation moving at constant speed. By means of an appropriate coordinate transformation, the transient version of this problem is used to obtain the steady state solution. The solution for the plane stress field is explicit and valid for dislocation speeds which are sub-, tran-, or super-sonic with respect to the material wave speeds. The previously discovered transonic speed at which the Mach head wave was annihilated for the transient problem, is found to be present in the steady state problem also. 相似文献
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Constitutive relations and field equations are developed for an elastic solid with voids subjected to electro-magnetic field. The linearized form of the relations and equations are presented separately when medium is subjected to a large magnetic field and when it is subjected to a large electric field. The possibility of propagation of time harmonic plane waves in an infinite elastic solid with voids has been explored. It is found that when the medium is subjected to large magnetic field, there exist two coupled longitudinal waves propagating with distinct speeds and a transverse wave mode. However, when the medium is subjected to a large electric field, there may propagate five basic waves comprising of four coupled longitudinal waves propagating with distinct speeds and a lone transverse wave. The effects of magnetic and electric fields are observed on the propagation characteristics of the existing waves. Under the limiting cases of frequency and for different electric conductive materials, the speeds of various waves are investigated. The phase speeds of different waves and their corresponding attenuations have been computed against the frequency parameter and depicted graphically for a specific material. 相似文献
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Pursuit evasion in a plane is formulated with both players allowed to vary their speeds between fixed limits. A suitable choice of real-space coordinates confers open-loop optimality on the game. The solution in the small is described in terms of the individual players' extremal trajectory maps (ETM). Each map is independent of role, adversary, and capture radius. An ETM depicts the actual real-space trajectories. A template method of generating constant control arcs is described. Examples of ETM for an aircraft flying at a constant altitude with fixed and varying speeds are presented. 相似文献
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Baljeet Singh 《Applied mathematics and computation》2010,217(2):705-715
The governing equations of thermoelasticity of transversely isotropic solid with initial stresses are formulated at uniform temperature. These equations are solved analytically in two-dimensions to show the existence of three plane quasi waves, namely, Quasi-Longitudinal (QL), Thermal (T-mode) and Quasi-Transverse (QT) waves. Reflection from a thermally insulated stress free surface of an initial stressed transversely isotropic thermoelastic solid half-space is studied. A particular model is chosen for the numerical computations of the propagation speeds, attenuation coefficients and reflection coefficients. Effects of initial stress parameter and thermal disturbances are observed on speeds of propagation, attenuation coefficients and reflection coefficients. 相似文献
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迟滞型材料阻尼转轴的分岔 总被引:8,自引:0,他引:8
应用平均法研究迟滞型材料阻尼转轴的分岔.首先用Hamilton原理推导出复数形式的转轴运动微分方程,然后用平均法求出各阶模态主共振时的平均方程,并分析定常解的稳定性,最后用奇异性理论分析正常运动和失稳运动响应(异步涡动)的分岔.研究表明,一定参数条件下,转轴在通过各阶临界转速(主共振)时,可能会因受到冲击而失稳(Hopf分岔).正常运动响应在不平衡量较大时有滞后和跳跃现象,而失稳运动响应是一类余维数较高的非对称分岔.由于内阻尼的非线性,响应随转速增加时还可能产生二次Hopf分岔,对应原系统的双调幅运动.做好动平衡及提高外阻尼水平是避免这种大幅值自激振动的有效措施. 相似文献