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Investigation of vibration. Measurement of vibration. The effect of vibration on humans

We have been acquainted with such a science as physics since our school days. Oscillations, frequencies, acceleration - all these concepts for certain you are familiar. In this article, we will consider in more detail such an important topic as vibration. Each of us faces this phenomenon in everyday life.

What is vibration? Definition can be given the following: it is oscillatory mechanical movements, which are transmitted directly to the human body. Its main physical characteristics are the frequency and amplitude of the oscillations. Measurement of vibration in amplitude is carried out in centimeters or meters, and in frequency - in hertz.

How should I assess vibration by acceleration and speed?

For any vibrational motion, the velocity and acceleration change continuously. The acceleration is greatest on the centerline of the oscillation, and in the extreme positions it is the smallest. Taking this into account, vibration measurement is carried out by acceleration and speed. The decibel record is from a reference vibration velocity (conditional), which is equal to 5 ∙ 10 8 m / s, and also vibration acceleration - 3 ∙ 10 4 m / s 2 . Vibration acceleration and vibration velocity are expressed relative to the zero thresholds in decibels. The threshold of perception is approximately 70 dB. The frequency of vibration of low-frequency does not exceed 32 Hz, and the high-frequency frequency is more than 32 Hz.

Sources of vibration

It is widely used in construction, industry, everyday life, agriculture, transport, electrical and pneumatic mechanized hand tools, various equipment and machinery, vehicles, machine tools. Vibration is widely used not only in technology, but also in medicine for the treatment of muscular and nervous diseases (vibro-massage, vibration therapy).

Exposure to vibration

Vibration is a factor that has great biological activity. The direction, depth and nature of the physiological shifts of different systems of the human body are determined by its spectral composition, levels and physical properties of the human body. An important role in the genesis of these reactions is played by analyzers - cutaneous, visual, motor, vestibular, etc.

It should be noted that the biochemical properties of the human body play a big role in subjective perception of vibration. Its action on the body is mediated by such phenomena as the physical impact of contact on the surface, the propagation through the tissues of vibrations, the direct reaction in tissues and organs to the effect, stimulation of the mechanoreceptors that cause subjective and neuroreceptor reactions.

Today, significant clinical and experimental material on this problem has been accumulated. The study of vibration showed that the disorders of motor function arising under its action are caused both by direct damage to muscles and by disturbances in the regulatory effects of the central nervous system. The predominance of diffuse shifts in this case can be explained by changes in the functioning of superspinal structures, and the greater degree of local changes in muscles that are directly traumatized. The most sensitive to the impact of local vibration are the departments of the sympathetic nervous system, which regulate the tone of the peripheral vessels, and the peripheral nervous system, which are associated with tactile and vibrational sensitivity.

The study of vibration gave the right to assert that the parameters of its effect primarily determine the direction of vascular disorders. At mechanical oscillations with a frequency of more than 35 Hz, spastic phenomena occur in the capillaries, and below is a picture of the atony of the capillaries. The most dangerous from the point of view of the possible development of vasospasm is the frequency range from 35 to 250 Hz.

Negative impact in the performance of work operations

Vibration can interfere with the direct way of performing work operations, and also indirectly affect the working capacity of a person by reducing it. Some authors, conducting a study of vibration, consider it as a strong stress factor, which has a negative impact on psychomotor performance. Besides, mental activity and emotional sphere suffers, and likelihood of accidents increases.

Vibrational speed

It is established that noise and vibration energetically act on the human body. Therefore, the latter began to be characterized by the spectrum of the vibrational speed expressed in centimeters per second or measured in decibels, as well as noise. The velocity, which is 5 ∙ 10 6 cm / sec, was conventionally accepted as the threshold value of mechanical oscillations. Only with direct contact of the body with the shuddering body or through the other solids touching it, mechanical vibrations are perceived (perceived). When they come into contact with their source, which generates a bass sound, vibration (the lowest frequencies), a concussion is also perceived with sound.

General and local

Distinguish between general and local vibration, depending on the spread of mechanical vibrations in parts of the human body. With a local, only a part of the body that is directly in contact with the surface is shaken, which shudders. Most often these are hands. This happens when working with some hand tools or when holding parts of the machine and other quivering objects.

Local vibration is sometimes transmitted to parts of the body that are connected by joints to organs directly exposed to it. But the amplitude of fluctuations of these parts of the body is usually lower, because as they pass through the tissues (especially soft) vibrations they gradually fade. On the contrary, the general vibration affects the whole body. This occurs mainly from mechanical vibrations of the surface where the worker is located.

Vibration disease

When the human organism is exposed to vestibular stimuli, the evaluation and perception of time are violated, and the speed of processing of information decreases. Violation of the coordination of motion causes low-frequency vibration. The most pronounced changes are noted at frequencies in the range from 4 to 11 Hz.

To the persistent pathological disturbances in the human body results in a prolonged exposure to vibration. A comprehensive analysis of this pathological process led to its isolation into a separate nosological form of the disease of a professional - a vibrational disease. She continues to hold one of the leading places among other occupational diseases. It generates the use of non-compliant hand machines, as well as the increasing specialization of labor, which leads to an increase in the total time of exposure to mechanical vibrations on the body. With increasing duration and intensity of exposure to vibration, the probability of developing this disease increases. In this case, individual sensitivity is essential. Overfatigue, cooling, noise, alcoholic intoxication, muscle tension, etc. intensify the harmful effect.

Stages of vibration disease

There are 4 stages of the disease in terms of severity:

- initial (I);

- moderately expressed (II);

- expressed (III);

- generalized (IV, extremely rare).

Negative impact of general vibration

General low-frequency vibration, especially the resonance range, can cause long-term traumatization of bone tissue and intervertebral discs, displacement of organs located in the abdominal cavity, and back pain, degenerative changes of the spine, chronic gastritis, etc.

Women exposed for a long time to the similar effects of women are noted to have an increased incidence of gynecological diseases, premature births, spontaneous abortions. Vibration low-frequency in women causes a violation of blood circulation in the pelvic organs.

Mechanical vibrations in residential buildings

The study of vibration is very important not only in production buildings, but also in residential buildings. The fact is that it poses a danger not only for the health of workers, but also for some other groups of the population. In residential buildings, the impact of vibration on a person is due to the use of industrial installations, transport, engineering and technological equipment. The most influenced by the organism in terms of intensity fluctuations urban rail transport: railways, open sections of the underground.

The vibration arising from the movement of trains in buildings has a discontinuous regular character. The amplitude of the oscillations decreases with distance from its source. Speaking about the spread of oscillations along the floors of a multi-storey building, it should be noted that, depending on the resonance, both amplification and weakening of vibration can be observed. In this case, the types of constructions of the premises do not exert a significant influence on its levels in residential premises in conditions of identical soils. Sometimes high vibrational levels are noted from the engineering and technological equipment (elevators) located in the buildings themselves, as well as built-in objects.

Methods of protection

Protection from vibration is very important in enterprises. Normalization of its levels, hygienically justified, is the basis for the prevention of vibration sickness. In this case, the direction, nature, duration of action are taken into account. In Russia, sanitary legislation regulates the levels of mechanical fluctuations that must be met at workplaces.

Protection from general vibration

The influence of vibration on a person should be reduced as much as possible. Occupational safety is a system of quantitative and qualitative characteristics and indicators that form the specificity of elements that ensure the absence of harmful effects of mechanical vibrations on the human body. Vibration protection is provided by:

- use of vibration-proof machines;

- use of special means of vibration protection;

- designing of industrial premises and technological processes, which ensure the observance of sanitary norms in the workplace;

- organizational and technical measures, the purpose of which is to improve the operation of used machines, organize their timely repair, and control vibration parameters;

- the creation of optimal modes of work and rest.

Means of individual protection, used when exposed to general vibration, is vibration-isolating footwear, soles, insoles. The most effective among all means of protection can be considered the elimination of direct human contact with the trembling equipment. This is done by using industrial robots, remote control, replacement and automation of technological operations.

Vibration protection means local

Reduction of its negative impact is achieved:

- by reducing its intensity directly at the source (use of handles with cushioning or vibration damping devices);

- by using external protection means, that is, elastic-damping devices and materials placed between the operator's hands and the source of mechanical vibrations (vibration-isolating gloves, mittens, gaskets and liners).

An important role in a complex of measures aimed at reducing the negative impact of vibration on the human body is given to the regimes of work and rest. The total time of contact with it, according to the mode of work, should be limited during the shift. It is recommended to take two breaks for physiotherapeutic procedures, outdoor activities, etc. The duration of the first should be 20 minutes (this break should be done 2 hours after the start time of the shift). The duration of the second is 30 minutes, it should be 2 hours after lunch break. A lunch break lasts for at least 40 minutes. The duration of continuous single exposure to the body of mechanical vibrations should not be more than 10-15 minutes.

To general health and medical and biological measures, serving for the prevention of vibration disease, include the following:

- hydroprocedures for hands (baths with warm water (+ 37-38 degrees) or use of dry air heating;

- Production gymnastics;

- self-massage and massage of the shoulder girdle and hands;

- Ultraviolet irradiation;

- the use of vitamins, as well as other activities of a general strengthening nature (an oxygen cocktail, a room for psychological unloading, etc.).

The importance and relevance of this topic is confirmed by the fact that it is being studied in school. Vibration is considered, in particular, in the textbook "Physics" (11 class). Of course, at school it is studied in a more general way. In particular, the vibrations of the Earth are considered. The frequency of our planet is 7.83 Hz. This quantity is called the Schumann wave, or Schumann resonance frequency. Some, however, believe that the Earth's vibrations have recently changed. For example, Anka Dinke, a Romanian physicist, believes that by December 2012 they had to reach 12.6-12.8 Hz. Human vibrations must correspond to the vibrations of the planet. Those who can tune in to new frequencies will benefit from the spiritual plan, as Anku Dinke believes. Vibration of a person is the topic of a separate article.

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