There are four main forms of vibration transmission to human body:
1) vibration is transmitted to the whole human body surface or other external surfaces at the same time.
2) Vibration is transmitted to the whole human body through a supporting surface, such as the feet of a standing person, the hips of a sitting person or the supporting surface of a lying person. This condition is usually called whole body vibration.
3) Vibration acts on some individual parts of the human body, such as the head or limbs. This kind of vibration (generally different from the whole body vibration) which is applied to some individual parts of the human body and only transmitted to a certain part of the human body is called local vibration.
4) There is another situation. Although vibration does not directly affect the human body, people can feel vibration through vision and hearing, and vibration will also affect people. This kind of vibration that does not directly affect people is called indirect vibration.
The harm and influence of vibration on operators are mainly manifested in two aspects:
1) Workers who work in vibration environment are often disturbed by vision, hindered by hands, and their energy is difficult to concentrate, which often leads to the decrease of working speed, production efficiency, fatigue of workers, and the possibility of quality accidents and even safety accidents.
2) If the vibration intensity is large enough, or the workers work in a vibration environment with the same intensity for a long time, the workers may cause injury or influence in nervous system, digestive system, cardiovascular system, endocrine system, respiratory system and so on.
The impact of vibration on residents mainly interferes with their daily activities such as sleeping, resting, reading and watching TV. It is worth noting that if residents live in an environment disturbed by vibration for a long time, over time, their long-term worries will also cause harm to their health.
2. Harm of vibration to buildings
When vibration acts on buildings, the structures of some buildings will be damaged due to the different vibration intensity and frequency. Common failure phenomena include cracking of foundation and wall, peeling of wall skin, sliding of stones, deformation and subsidence of foundation, etc. Even buildings may collapse.
3. The influence of vibration on precision instruments and equipment
The influence of vibration on precision instruments and equipment is mainly manifested in the following three aspects:
1) vibration will affect the normal work of precision instruments, affect the accuracy and reading speed of instrument calibration, and even make the calibration unreadable. If the vibration is too large, it will directly affect the service life of the instrument and even damage it.
2) For some sensitive electrical appliances, such as sensitive relays, vibration may even lead to their misoperation, thus causing some major accidents.
3) Vibration will reduce the machining accuracy of precision machine tools, increase the roughness, and make the quality impossible to guarantee. Excessive vibration will directly damage the tools and precision parts of precision machine tools.
4. Vibration produces noise
Vibrating objects can radiate noise directly into space, which is air sound. Vibration will spread in the soil, which will cause vibration of building foundation, wall, beam and column, ceiling, doors and windows, pipes and so on. The vibration of these objects will radiate noise again, which is called solid sound transmission. Obviously, solid sound increases the harm and influence of noise.