BASIC PRINCIPLES IN OCCUPATIONAL HYGIENE 职业卫生基本原则

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1 BASIC PRINCIPLES IN OCCUPATIONAL HYGIENE 职业卫生基本原则
Day 3 第3天

2 14 – VIBRATION 14-振动

3 VIBRATION 振动 Vibration is the mechanical oscillations of an object about an equilibrium point. 振动是物体围绕一个平衡点作机械振荡。 The oscillations may be regular such as the motion of a pendulum or random such as the movement of a tire on a gravel road. 振荡可能是有规律的（如钟摆的运动），也可能是随机的（如轮胎在砂石路上的移动）。 If we could watch a vibrating object in slow motion, you could see movements in different directions. 细看放慢后移动的振动物体，我们可以看到不同方向的运动。

4 VIBRATION 振动 振幅 时间 位移 振动物体 1个周期 个周期 个周期

5 VIBRATION 振动 Any vibration has two measurable quantities. How far (amplitude or intensity), and how fast (frequency) the object moves helps determine its vibrational characteristics. 所有振动都有两个可量值。振动距离（振幅或强度）和振动速度（频率）—有助于确定振动特性。 Frequency 频率 The number of cycles that a vibrating object completes in one second is called frequency. 频率系指振动物体在一秒钟内完成周期性振动的次数。 The unit of frequency is hertz (Hz). 频率的单位是赫兹（Hz）。 One hertz equals one cycle per second. 一赫兹等于每秒一个周期。 Amplitude - Amplitude is the distance from the stationary position to the extreme position on either side and is measured in metres (m). The intensity of vibration depends on amplitude. 振幅—振动物体离开平衡位置的最大距离，振幅单位为米（m）。振幅表示振动强度。

6 Acceleration (measure of vibration intensity) 加速度（振动强度的度量）
Acceleration is a measure of how quickly speed changes with time. 加速度是速度对时间的变化率 。 The measure of acceleration is expressed in units of (metres per second) per second or metres per second squared (m/s2). 加速度单位为米/每秒，或米/每二次方秒。 The magnitude of acceleration changes from zero to a maximum during each cycle of vibration. 加速度幅度是振动物体在一个振动周期内从零速度到最大速度 的变化。 It increases as vibrating object moves further from its normal stationary position. 振动物体离平衡位置越远，加速度越大。

7 Exposure to Vibration (1) 振动风险 (1)
Exposure to vibration normally occurs during the operation of powered machinery such as hand tools or whilst travelling on vehicles. 振动风险通常在采用手工具等的动力机械操作时或车辆行驶过程中发生。 Hand-arm vibration 手臂振动 Whole-body vibration 全身振动 Vibration induced health conditions progress slowly. 振动引起的健康风险通常发展较缓。

8 Exposure to Vibration (2) 振动风险 (2)
Vibration-induced white finger (VWF) 振动引起的白指（VWF） Attacks of whitening (blanching) of one or more fingers when exposed to cold. 一个或多个手指在零下温度时变白（热烫）。 Tingling and loss of sensation in the fingers. 手指刺痛和没有知觉。 Loss of light touch. 无轻触感。 Pain and cold sensations between periodic white finger attacks. 两次白指定期发作间出现疼痛和冷觉。 Loss of grip strength. 握力不佳。 Bone cysts in fingers and wrists. 手指和手腕出现骨囊肿。

9 Measurement of Vibration 振动测量
Vibration is usually measured by the use of accelerometers. 通常采用加速度计来测量振动。 Attached to the hand of a worker or tool. 将加速度计与工作人员的手或工具相连， 即可测量。 Unlike noise measurements, vibration ones have a subjective element. 与噪声测量不同，振动只有一个主观因素。