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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 :( g; `7 j/ \; E3 r' e9 G% X( |9 m
The oscillating member is moved backwards and forwards through an angle of 90° (45° on : n$ v, n( U- d' e8 C
either side of the vertical), the number of flexings being 20 000 and the rate of flexing 60 per
- s4 C9 h8 \, t0 {8 @; zmin. A flexing is one movement, either backwards or forwards. After 10 000 flexings, the % ~3 x v& L% X7 _8 x
sample is turned through 90° about the centre line of the cord guard. % o, @* }: j% I* j
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8 h$ j! s% ]5 f翻译成中文的主要意思就是：/ N7 c+ t' i, s! | r
" X' M) Z$ a# _The oscillating member is moved backwards and forwards through an angle of 90° (45° on
7 v9 P/ K+ g I) W% m" Peither side of the vertical), the number of flexings being 20 000 and the rate of flexing 60 per 1 k) N) ^4 N* r+ J, o2 e
min. - 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。, A* {5 S* q# r) r/ y9 B! W
$ O: H; W( _. x; ~& c2 q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。
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' k2 s; E% N3 F) D3 K5 |After 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°。
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5 m3 t& R" ^8 v: m" b: a' y0 e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。
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2 l* b' |- ~7 A4 a- D) M0 u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°。5 g% l/ k# {5 s7 S2 l. s
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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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