FREE WAVE PROPAGATION IN PERIODICALLY SUPPORTED, INFINITE BEAMS
FREE WAVE PROPAGATION IN PERIODICALLY SUPPORTED, INFINITE BEAMS
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DOI：
10.1016/s0022-460x(70)80062-1
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发表时间：
1970-01-01
影响因子：
4.7
通讯作者：
MEAD, DJ
中科院分区：
文献类型：
--
作者：
MEAD, DJ
首先回顾了无限长梁在等间距支承上自由简谐运动的传播常数的概念。在此基础上，给出了刚性支承上施加弹性转动约束的梁和柔性支承上的梁的弯曲传播常数的表达式。刚性支承上的梁只有一个传播常数，而柔性支承上的梁在每个频率上都有两个传播常数，对传播常数的详细考虑可以得出这样的结论：在这种梁中自由传播的简谐弯曲波必须视为一个波群，其分量具有不同的波长、相速度和方向。分析了某些特殊情况下各分量的大小。定性地考虑了这些群与对流压力场之间的相互作用。有一种机制被证明是存在的，在这种机制下，缓慢的亚音速对流压力场可以产生能够辐射声音的超音速弯曲波。
The notion of propagation constants for the free harmonic motion of infinite beams on identical, equi-spaced supports is first reviewed. Expressions are then derived for the flexural propagation constants for beams on rigid supports which exert elastic rotational restraint, and also for beams on flexible supports. A beam on rigid supports has one propagation constant and a beam on flexible supports has two propagation constants for each frequency.Detailed consideration of the propagation constant leads to the conclusion that a freely propagating harmonic flexural wave in such a beam must be regarded as a wave group, having components of different wavelength, phase velocity and direction. The magnitudes of the components in some special cases are examined. The interaction between these groups and convected pressure fields is considered in qualitative terms. A mechanism is shown to exist whereby slow, subsonic convected pressure fields can generate flexural waves of supersonic velocity which can radiate sound.