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发表于 2009-5-8 15:06
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引用第10楼franco于2009-05-07 20:39发表的 :
/ [- V' o" h: N$ \6 D* ZThe oscillating member is moved backwards and forwards through an angle of 90° (45° on
* Y* \4 M6 S0 P3 v& x: w" a6 eeither side of the vertical), the number of flexings being 20 000 and the rate of flexing 60 per & u1 r* H2 K* A4 L& K
min. A flexing is one movement, either backwards or forwards. After 10 000 flexings, the 6 \2 k" {0 I0 T K+ d! Q
sample is turned through 90° about the centre line of the cord guard. " Y. v2 j2 m1 L- N8 r, ?, X
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.......
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- s8 j- b* J R% |/ D翻译成中文的主要意思就是：
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& s/ ]) | F& H% ]* I2 h* vThe oscillating member is moved backwards and forwards through an angle of 90° (45° on
& k# r; C. ?. x5 O( e, U7 x. leither side of the vertical), the number of flexings being 20 000 and the rate of flexing 60 per
: ~' n4 E: Y) y$ Dmin. - 摇摆装置能够在90°的范围内前后摆动（其中这个90°指的是沿垂直位置两边各45°），以每分钟60次的频率摇摆20000次。0 f9 J8 O @0 X q1 m! E, c
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这句话讨论的是仪器的摆动机构要满足的特性，就是要能在90°的范围内前后摆动，如果只能在45°的范围内摆动的话，这个设备就是不符合要求的。这句话并没有涉及到一个摆动周期如何定义啊。1 { T& E0 E U) t& z7 j {9 R
* E- d: L9 Y M- b8 H s Z+ j) A' fAfter 10 000 flexings, the sample is turned through 90° about the centre line of the cord guard. - 10000次摆动之后，将样品沿着电线防护套的中心线转动90°。. z/ B4 f6 [9 O4 N0 K
7 @/ Q. T8 x+ D p1 a A; M" t* p这句话说的是总共20000次的摆动样品应该在两个位置分两次完成而已，同样没有涉及到摆动周期的解释和说明。. ]$ D8 r, I6 B* ?* n8 l4 P) \
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最重要的一句话应该是：A flexing is one movement, either backwards or forwards. - 一次摇摆就是一次移动，无论是向后还是向前的。
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这句话虽然容易引起歧义，但是仔细考虑一下也不是很难理解。可以看出，1个摆动周期就是单次的向前或者向后的移动。摇摆机构是在总共90°范围内摆动，那不管是向前还是向后的摆动角度都是45°了。由此可以得出1个摇摆周期就是45°而不是我们通常认为的90°。
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摘抄UL 745-1标准中的相关章节如下，关于这个问题解释的非常清楚，供大家参考参考：
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A flexing is one movement, either backwards or forwards. That is, from vertical to 45° in one direction is the first flex, from there back to vertical is the second flex, from vertical to the opposite 45° is the third flex, from there back to vertical is the fourth flex, continuing until 10000 flexes have occurred. |
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发表于 2009-5-7 20:39
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