Beneficial effects of resonance. Resonance is a physical phenomenon. Theory and real examples. Resonance method of ice destruction

05.11.2022

The word "resonance" is used by people every day in a variety of different ways. It is pronounced by politicians and TV presenters, written by scientists in their works, and studied by schoolchildren in lessons. This word has several meanings relating to different areas of human activity.

Where does the word resonance come from?

We all learn what resonance is for the first time from a school physics course. In scientific dictionaries, this term is given a detailed explanation from the point of view of mechanics, electromagnetic radiation, optics, acoustics and astrophysics.

From a technical point of view, resonance is a phenomenon of the response of an oscillatory system and not an external influence. When the periods of influence and response of the system coincide, resonance occurs - a sharp increase in the amplitude of the oscillations in question.

The simplest example of mechanical resonance is given in his works by the medieval scientist Toricelli. A precise definition of the phenomenon of resonance was given by Galileo Galilei in his work on pendulums and the sound of musical strings. What is electromagnetic resonance, explained in 1808 by James Maxwell, founder of modern electrodynamics.

You can find out what “resonance” is not only in Wikipedia, but in the following reference publications:

physics textbooks for grades 7-11;
physical encyclopedia;
scientific and technical encyclopedic dictionary;
dictionary of foreign words of the Russian language;
philosophical encyclopedia.

Resonance in polemics and rhetoric

The word “resonance” acquired another meaning in the field of social sciences. This word refers to the public’s response to a certain phenomenon in people’s lives, a certain statement, or incident. Typically, the word “resonance” is used when something causes many people to have a similar and very strong reaction at the same time. There is even a commonly used expression “wide public resonance”, which is a speech cliche. It is best to avoid it in your own speech, written or oral.

In the philosophical dictionary, resonance is interpreted as a concept that has a figurative meaning and is understood as agreement or like-mindedness of two people, two souls in compassion, sympathy or antipathy, empathy or indignation.

In the meaning of “strong response”, “unanimous assessment”, the word resonance is very popular with politicians, speakers, and announcers. It helps to convey an emotional upsurge, a unanimous impulse, and emphasize the significance of what is happening.

Where do we meet resonance?

In the literal sense, the word resonance should be used in relation to many natural processes occurring around us. All children who ride on a regular swing or carousel on a playground exploit mechanical resonance.

Housewives, heating food in the microwave, use electromagnetic resonance. The television and radio broadcasting network, the operation of mobile phones and wifi for the Internet are built on the principles of resonance.

Sound resonance allows us to enjoy music or indulge in echoes in mountains and indoor spaces where the walls do not have sufficient sound insulation. The operation of echo sounders and many other measuring instruments is based on the principle of acoustic resonance.

Why is resonance dangerous?

In the natural scientific sense, resonance as a phenomenon can not only be useful to humans, but also dangerous. The most striking example is construction.

When designing buildings and structures, structural calculations for resonance are strictly necessary. This is how all high-rise buildings, towers, power line supports, transmitting and receiving antennas, as well as high-rise buildings that resonate with winds at high altitudes are calculated.

All bridges and extended objects must be checked for resonance. In 2010, a video of a bridge across the Volga, which spread like a silk ribbon, spread all over the Internet. The results of the investigation showed that the bridge structures resonated with the wind.

A similar incident occurred in the USA. On November 7, 1940, one of the spans of the Tacoma Suspension Bridge, located in Washington state, collapsed. Even during construction, experts noted vibrations of the bridge deck associated with the wind and the low height of the supports. As a result of the collapse, numerous studies and calculations were carried out, which became the basis for modern bridge construction technologies. Among specialists, even the term “Tacoma Bridge” arose, meaning the poor quality of construction calculations.

Each of us encounters resonance every day. You need to remember this phenomenon in everyday life, whether you decide to swing on a pedestrian bridge or put metal utensils in the microwave (this is prohibited by the rules). And the word “resonance” itself can be used in your speech to decorate it and enhance the impression of what you said.

From the course of study at school and institute, many learned the definition of resonance as the phenomenon of a gradual or sharp increase in the amplitude of vibrations of a certain body when an external force is applied to it with a certain frequency. However, few can answer the question of what resonance is with practical examples.

Physical definition and binding to objects

Resonance, by definition, can be understood as A fairly simple process:

there is a body that is at rest or oscillates with a certain frequency and amplitude;
it is acted upon by an external force with its own frequency;
in the case when the frequency of the external influence coincides with the natural frequency of the body in question, a gradual or sharp increase in the amplitude of oscillations occurs.

However, in practice the phenomenon is considered as a much more complex system. In particular, the body can be represented not as a single object, but as a complex structure. Resonance occurs when the frequency of the external force coincides with the so-called total effective oscillatory frequency of the system.

Resonance, if we consider it from the standpoint of physical definition, must certainly lead to the destruction of the object. However, in practice there is a concept of the quality factor of an oscillatory system. Depending on its value, resonance can lead to various effects:

with a low quality factor, the system is not able to retain oscillations coming from outside to a large extent. Therefore, there is a gradual increase in the amplitude of natural vibrations to a level where the resistance of materials or connections does not lead to a stable state;
high quality factor, close to unity, is the most dangerous environment in which resonance often leads to irreversible consequences. These may include both mechanical destruction of objects and the release of large amounts of heat at levels that can lead to fire.

Also, resonance occurs not only under the action of an external force of an oscillatory nature. The degree and nature of the system's response is, to a large extent, responsible for the consequences of externally directed forces. Therefore, resonance can occur in a variety of cases.

A textbook example

The most common example used to describe the phenomenon of resonance is the case when a company of soldiers walked along a bridge and collapsed it. From a physical point of view, there is nothing supernatural in this phenomenon. Walking in step, soldiers caused hesitation, which coincided with the natural effective oscillatory frequency of the bridge system.

Many people laughed at this example, considering the phenomenon only theoretically possible. But advances in technology have proven the theory.

There is a real video online of the behavior of a pedestrian bridge in New York, which constantly swayed violently and almost collapsed. The author of the creation, which with its own mechanics confirms the theory when resonance arises from the movement of people, even chaotic ones, is a French architect, author of the Millau Viaduct suspension bridge, a structure with the highest supporting columns.

The engineer had to spend a lot of time and money to reduce the quality factor of the system footbridge to an acceptable level and ensure that there are no significant vibrations. An example of the work on this project is an illustration of how the effects of resonance can be curbed in low-Q systems.

Examples that are repeated by many

Another example, which is even included in jokes, is the breaking of dishes by sound vibrations, from practicing the violin and even singing. Unlike a company of soldiers, this example was repeatedly observed and even specially tested. Indeed, the resonance that occurs when the frequencies coincide leads to the splitting of plates, glasses, cups and other utensils.

This is an example of process development under conditions of a high-quality system. The materials from which the dishes are made are sufficiently elastic media, in which the oscillations propagate with low attenuation. The quality factor of such systems is very high, and although the frequency coincidence band is quite narrow, resonance leads to a strong increase in amplitude, as a result of which the material is destroyed.

Example of a constant force

Another example where the destructive effect was manifested was the collapse of the Tacoma Suspension Bridge. This case and the video of the wave-like rocking of the structure are even recommended for viewing at university physics departments, as the most textbook example of such a resonance phenomenon.

The destruction of a suspension bridge by wind is an illustration of how a relatively constant force causes resonance . The following happens:

a gust of wind deflects part of the structure - an external force contributes to the occurrence of vibrations;
when the structure moves in reverse, air resistance is not enough to dampen the vibration or reduce its amplitude;
due to the elasticity of the system, a new movement begins, which strengthens the wind, which continues to blow in one direction.

This is an example of the behavior of a complex object, where resonance develops against a background of high quality factor and significant elasticity, under the influence of constant force in one direction. Unfortunately, the Tacoma Bridge is not the only example of structural collapse. Cases have been and are being observed all over the world, including in Russia.

Resonance can also be used under controlled, well-defined conditions. Among the many examples, one can easily recall radio antennas, even those developed by amateurs. The principle of resonance when absorbing energy is applied here electromagnetic wave. Each system is developed for a separate frequency band in which it is most effective.

MRI installations use a different type of phenomenon - different absorption of vibrations by cells and structures of the human body. The nuclear magnetic resonance process uses radiation of different frequencies. The resonance that occurs in tissues leads to easy recognition of specific structures. By changing the frequency, you can explore certain areas and solve various problems.

March 02 2016

Resonance is a sharp increase in the amplitude of forced oscillations, which occurs when the frequency of the external influence approaches certain values (resonance frequencies) determined by the properties of the oscillatory system. An increase in amplitude occurs when the external (exciting) frequency coincides with the internal (natural) frequency of the oscillatory system. With the help of resonant phenomena, even very weak harmonic vibrations can be isolated and/or amplified. Resonance is a phenomenon in which the oscillatory system is particularly responsive to the influence of a certain frequency of the driving force.

There are quite a few situations in our lives in which resonance manifests itself. For example, if you bring a ringing tuning fork to a stringed musical instrument, the acoustic wave emanating from the tuning fork will cause vibration of the string tuned to the frequency of the tuning fork, and it will sound itself.

Another example, the well-known experiment with a thin-walled glass. If you measure the frequency of sound at which a glass rings, and apply sound with the same frequency from a frequency generator, but with a larger amplitude, through an amplifier and speaker back to the glass, its walls resonate with the frequency of the sound coming from the speaker and begin to vibrate. Increasing the amplitude of this sound to a certain level leads to the destruction of the glass.

Bioresonance: from Ancient Rus' to the present day

Our Orthodox ancestors, tens of thousands of years before the arrival of Christianity in Rus', knew well about the power of bell ringing and tried to install a bell tower in every village! Due to this, in the Middle Ages, Rus', rich in church bells, avoided the devastating plague epidemics, unlike Europe (Gaul), in which holy inquisitors burned at the stake not only all scientists and knowledgeable people, but also all the ancient “heretical” books written in the Glagolitic alphabet that kept unique knowledge of our ancestors, including the power of resonance!

Thus, all Orthodox knowledge accumulated over centuries was prohibited, destroyed and replaced by the new Christian faith. However, to this day, data on bioresonance are prohibited. Even after centuries, any information about treatment methods that do not bring profit to the pharmaceutical industry is kept silent. While the annual multi-billion dollar turnover of pharmaceuticals is growing every year.

A striking example of the use of resonant frequencies in Rus', and this is a fact that cannot be avoided. When a plague epidemic broke out in Moscow in 1771 (1771), Catherine II sent Count Orlov from St. Petersburg with four Life Guards and a huge staff of doctors. All life in Moscow was paralyzed. In order to ward off the “pestilence”, the laity fumigated their homes, lit huge fires in the streets, and all of Moscow was shrouded in black smoke, since it was then believed that the plague spread through the air, but this did not help much. They also rang the alarm (the largest bell) and all the smaller bells with all their might for 3 days in a row, as they firmly believed that the ringing of the bells would ward off terrible misfortune from the city. A few days later the epidemic began to recede. "What's the secret?" - you ask. In fact, the answer lies on the surface.

Now let’s look at a well-known example of the use of bioresonance in our time. In order to maintain the purity of the experiment, doctors placed metal plates in the ward with cancer patients, similar to those used in ancient monasteries, so that the patients could not associate the bells with the church, and self-hypnosis, born involuntarily, could not significantly affect the results of the research. When selecting individual frequencies for each patient, many titanium plates of various sizes were used. The result exceeded all expectations!

After exposure to acoustic waves of a certain frequency on the biologically active points of the patients, 30% of the patients stopped having pain and were able to fall asleep, and another 30% of the patients stopped having pain that was not relieved by the strongest narcotic anesthetics!

Currently, to achieve the resonance effect, there is no need to use huge bells, but there is a unique opportunity to use the achievements of science and technology, created electronic devices based on frequency resonance, in other words, Smart Life bioresonance therapy devices.

The resonance effect in biological structures can be caused by:

Acoustic waves

Mechanical impact

Electromagnetic waves in the visible and radio frequency ranges

Magnetic field pulses

Pulses of weak electric current

Pulsed thermal effects

That is, the resonance effect in biological structures can be caused by external influences and any physical phenomena that arise during biochemical reactions inside a living cell. Moreover, each biological structure has its own unique frequency spectrum that accompanies biochemical processes and responds to external influences, both the main resonant frequency and higher or lower harmonics from the main frequency, with an amplitude as many times greater as these harmonics are distant from the frequency of the main resonance .

How can you use the power of resonance in everyday life, and what method of influence should you choose?

Acoustic waves

Guess what happens to tartar when it is removed, using ultrasound in the dentist's office or when breaking up kidney stones? The answer is obvious. And without a doubt, acoustic exposure is an excellent opportunity for healing the body, if not for one “but”. Bells weigh a lot, are expensive, create a lot of noise, and can only be used permanently.

A magnetic field

To cause at least any noticeable effect from the influence of a pulsating magnetic field on the entire body, it is necessary to make an electromagnet of enormous size and weighing a couple of tons; it will occupy half the room and consume a lot of electricity. The inertia of the system will not allow its use at high frequencies. Small electromagnets can only be used locally due to their short range. You also need to know exactly the areas on the body and the frequency of exposure. The conclusion is disappointing: using a magnetic field to treat diseases is not economically feasible at home.

Electricity Electromagnetic waves
For the frequency resonance method, you can use radio waves with a carrier frequency from 10 kHz to 300 MHz, since this range has the lowest absorption coefficient of electromagnetic waves by our body and it is transparent to them, as well as electromagnetic waves in the visible and infrared spectrum. Visible red light with a wavelength from 630 nm to 700 nm penetrates tissue to a depth of 10 mm, and infrared light from 800 nm to 1000 nm penetrates to a depth of 40 mm and deeper, also causing some thermal effects when braking in tissue. To influence biologically active zones on the surface of the skin, you can use radio waves with a carrier frequency of up to ~ 50 GHz

resonance

Dictionary of medical terms

Explanatory Dictionary of the Living Great Russian Language, Dal Vladimir

resonance

m. French sound, hum, paradise, echo, leave, hum, return, voice; the sonority of the voice, by location, by the size of the room; sonority, sonority of a musical instrument, according to its design.

In grand piano, piano, gusli: deck, deck, old. shelf, board along which strings are stretched.

Explanatory dictionary of the Russian language. D.N. Ushakov

resonance

resonance, plural no, m. (from Latin resonans - giving Echo).

The response sound of one of two bodies tuned in unison (physical).

The ability to increase the strength and duration of sound, characteristic of rooms, the inner surface of which can reflect sound waves. There is a good resonance in the concert hall. There is poor resonance in the room.

Excitation of vibration of a body caused by vibrations of another body of the same frequency and transmitted by an elastic medium located between them (mechanical).

The relationship between self-induction and capacitance in an alternating current circuit that causes maximum electromagnetic oscillations of a given frequency (physical, radio).

Explanatory dictionary of the Russian language. S.I.Ozhegov, N.Yu.Shvedova.

resonance

Excitation of vibrations of one body by vibrations of another of the same frequency, as well as the response sound of one of two bodies tuned in unison (special).

The ability to amplify sound, characteristic of resonators or rooms whose walls reflect sound waves well. R. violins.

adj. resonant, -th, -oe (to 1 and 2 values). Resonance spruce (for making musical instruments; special).

New explanatory dictionary of the Russian language, T. F. Efremova.

resonance

Excitation of vibrations of one body by vibrations of another of the same frequency, as well as the response sound of one of two bodies tuned in unison.

Encyclopedic Dictionary, 1998

resonance

RESONANCE (French resonance, from Latin resono - I respond) is a sharp increase in the amplitude of steady-state forced oscillations as the frequency of an external harmonic influence approaches the frequency of one of the natural oscillations of the system.

Resonance

(French resonance, from Latin resono ≈ I sound in response, I respond), the phenomenon of a sharp increase in the amplitude of forced oscillations in any oscillatory system, which occurs when the frequency of a periodic external influence approaches certain values determined by the properties of the system itself. In the simplest cases, R. occurs when the frequency of the external influence approaches one of those frequencies with which natural oscillations occur in the system, arising as a result of the initial shock. The nature of the R. phenomenon depends significantly on the properties of the oscillatory system. Regeneration occurs most simply in cases where a system with parameters that do not depend on the state of the system itself (so-called linear systems) is subjected to periodic action. Typical features of R. can be clarified by considering the case of harmonic action on a system with one degree of freedom: for example, on a mass m suspended on a spring under the action of a harmonic force F = F0 coswt ( rice. 1), or an electrical circuit consisting of series-connected inductance L, capacitance C, resistance R and a source of electromotive force E, varying according to a harmonic law ( rice. 2). For definiteness, the first of these models is considered below, but everything said below can be extended to the second model. Let us assume that the spring obeys Hooke’s law (this assumption is necessary for the system to be linear), i.e., that the force acting from the spring on the mass m is equal to kx, where x ≈ displacement of the mass from the equilibrium position, k ≈ elasticity coefficient (gravity is not taken into account for simplicity). Further, let the mass, when moving, experience resistance from the environment that is proportional to its speed and the coefficient of friction b, i.e., equal to k (this is necessary for the system to remain linear). Then the equation of motion of mass m in the presence of a harmonic external force F has the form: ═══(

where F0≈ oscillation amplitude, w ≈ cyclic frequency equal to 2p/T, T ≈ period of external influence, ═≈ mass acceleration m. The solution to this equation can be represented as the sum of two solutions. The first of these solutions corresponds to free oscillations of the system arising under the influence of the initial push, and the second ≈ forced oscillations. Due to the presence of friction and resistance of the medium, natural oscillations in the system always dampen, therefore, after a sufficient period of time (the longer, the less the damping of natural oscillations), only forced oscillations will remain in the system. The solution corresponding to forced oscillations has the form:

and tgj = . Thus, forced oscillations are harmonic oscillations with a frequency equal to the frequency of the external influence; the amplitude and phase of forced oscillations depend on the relationship between the frequency of the external influence and the parameters of the system.

The dependence of the amplitude of displacements during forced vibrations on the relationship between the values of mass m and elasticity k is most easily traced, assuming that m and k remain unchanged, and the frequency of the external influence changes. With a very slow action (w ╝ 0), the displacement amplitude x0 »F0/k. With increasing frequency w, the amplitude x0 increases, since the denominator in expression (2) decreases. When w approaches the value ═ (i.e., the value of the frequency of natural oscillations with low damping), the amplitude of forced oscillations reaches a maximum ≈ P occurs. Then, with an increase in w, the amplitude of oscillations monotonically decreases and at w ╝ ¥ tends to zero.

The amplitude of oscillations during R. can be approximately determined by setting w = . Then x0 = F0/bw, i.e., the amplitude of oscillations during R. is greater, the lower the damping b in the system ( rice. 3). On the contrary, as the attenuation of the system increases, the radiation becomes less and less sharp, and if b is very large, then the radiation ceases to be noticeable at all. From an energy point of view, R. is explained by the fact that such phase relationships are established between the external force and forced oscillations in which the greatest power enters the system (since the speed of the system is in phase with the external force and the most favorable conditions are created for the excitation of forced oscillations ).

If a linear system is subject to a periodic, but not harmonic, external influence, then R. will occur only when the external influence contains harmonic components with a frequency close to the natural frequency of the system. In this case, for each individual component the phenomenon will proceed in the same way as discussed above. And if there are several of these harmonic components with frequencies close to the natural frequency of the system, then each of them will cause resonant phenomena, and the overall effect, according to the superposition principle, will be equal to the sum of the effects from individual harmonic influences. If the external influence does not contain harmonic components with frequencies close to the natural frequency of the system, then R. does not occur at all. Thus, the linear system responds, “resonates” only to harmonic external influences.

In electrical oscillatory systems consisting of a series-connected capacitance C and inductance L ( rice. 2), R. is that when the frequencies of the external emf approach the natural frequency of the oscillatory system, the amplitudes of the emf on the coil and the voltage on the capacitor separately turn out to be much greater than the amplitude of the emf created by the source, but they are equal in magnitude and opposite in phase. In the case of a harmonic emf acting on a circuit consisting of capacitance and inductance connected in parallel ( rice. 4), there is a special case of R. (anti-resonance). As the frequency of the external emf approaches the natural frequency of the LC circuit, there is not an increase in the amplitude of forced oscillations in the circuit, but, on the contrary, a sharp decrease in the amplitude of the current in the external circuit feeding the circuit. In electrical engineering, this phenomenon is called R. currents or parallel R. This phenomenon is explained by the fact that at a frequency of external influence close to the natural frequency of the circuit, the reactances of both parallel branches (capacitive and inductive) turn out to be the same in value and therefore flow in both branches of the circuit currents are approximately the same amplitude, but almost opposite in phase. As a result, the amplitude of the current in the external circuit (equal to the algebraic sum of the currents in the individual branches) turns out to be much smaller than the amplitude of the current in the individual branches, which, with parallel flow, reach their greatest value. Parallel R., as well as serial R., is expressed the more sharply, the lower the active resistance of the branches of the R. circuit. Serial and parallel R. are called voltage R. and current R., respectively.

In a linear system with two degrees of freedom, in particular in two coupled systems (for example, in two coupled electrical circuits; rice. 5), the phenomenon of R. retains the main features indicated above. However, since in a system with two degrees of freedom, natural oscillations can occur with two different frequencies (the so-called normal frequencies, see Normal oscillations), then R. occurs when the frequency of a harmonic external influence coincides with both one and the other. with a different normal system frequency. Therefore, if the normal frequencies of the system are not very close to each other, then with a smooth change in the frequency of the external influence, two maximum amplitudes of forced oscillations are observed ( rice. 6). But if the normal frequencies of the system are close to each other and the attenuation in the system is sufficiently large, so that the R. at each of the normal frequencies is “dull,” then it may happen that both maxima merge. In this case, the R. curve for a system with two degrees of freedom loses its “double-humped” character and in appearance differs only slightly from the R. curve for a linear contour with one degree of freedom. Thus, in a system with two degrees of freedom, the shape of the R curve depends not only on the damping of the contour (as in the case of a system with one degree of freedom), but also on the degree of connection between the contours.

In coupled systems there is also a phenomenon that is to a certain extent similar to the phenomenon of antiresonance in a system with one degree of freedom. If, in the case of two connected circuits with different natural frequencies, adjust the secondary circuit L2C2 to the frequency of the external emf included in the primary circuit L1C1 ( rice. 5), then the current strength in the primary circuit drops sharply and the more sharply, the less attenuation of the circuits. This phenomenon is explained by the fact that when the secondary circuit is tuned to the frequency of the external emf, just such a current arises in this circuit that induces an induction emf in the primary circuit, approximately equal to the external emf in amplitude and opposite to it in phase.

In linear systems with many degrees of freedom and in continuous systems, control retains the same basic features as in a system with two degrees of freedom. However, in this case, unlike systems with one degree of freedom, the distribution of external influence along individual coordinates plays a significant role. In this case, such special cases of distribution of external influence are possible in which, despite the coincidence of the frequency of the external influence with one of the normal frequencies of the system, R. still does not occur. From an energy point of view, this is explained by the fact that such phase relationships are established between the external force and forced oscillations in which the power supplied to the system from the excitation source along one coordinate is equal to the power given by the system to the source along the other coordinate. An example of this is the excitation of forced vibrations in a string, when an external force coinciding in frequency with one of the normal frequencies of the string is applied at a point that corresponds to the velocity node for a given normal vibration (for example, a force coinciding in frequency with the fundamental tone of the string is applied at the very end of the string). Under these conditions (due to the fact that the external force is applied to a fixed point of the string), this force does not do any work, power from the source of the external force does not enter the system, and no noticeable excitation of string oscillations occurs, i.e., no vibration is observed. .

R. in oscillatory systems, the parameters of which depend on the state of the system, that is, in nonlinear systems, has a more complex character than in linear systems. R. curves in nonlinear systems can become sharply asymmetrical, and the phenomenon of R. can be observed at different ratios of the frequencies of influence and the frequencies of natural small oscillations of the system (the so-called fractional, multiple, and combination R.). An example of R. in nonlinear systems is the so-called. ferroresonance, i.e. resonance in an electrical circuit containing inductance with a ferromagnetic core, or ferromagnetic resonance, which is a phenomenon associated with the reaction of elementary (atomic) magnets of a substance when a high-frequency magnetic field is applied (see Radio spectroscopy).

If an external influence produces periodic changes in the energy-intensive parameters of an oscillatory system (for example, capacitance in an electrical circuit), then at certain ratios of the frequencies of changes in the parameter and the natural frequency of free oscillations of the system, parametric excitation of oscillations, or parametric R, is possible.

R. is very often observed in nature and plays a huge role in technology. Most structures and machines are capable of performing their own vibrations, so periodic external influences can cause them to vibrate; for example, the movement of a bridge under the influence of periodic shocks when a train passes along the joints of rails, the movement of the foundation of a structure or the machine itself under the influence of not completely balanced rotating parts of the machines, etc. There are known cases when entire ships entered into the movement at certain numbers of propeller revolutions shaft In all cases, R. leads to a sharp increase in the amplitude of forced vibrations of the entire structure and can even lead to the destruction of the structure. This is a harmful role of R., and to eliminate it, the properties of the system are selected so that its normal frequencies are far from the possible frequencies of external influence, or the phenomenon of anti-resonance is used in one form or another (so-called vibration absorbers, or dampers, are used). In other cases, radio plays a positive role, for example: in radio engineering, radio is almost the only method that allows you to separate the signals of one (desired) radio station from the signals of all other (interfering) stations.

Lit.: Strelkov S.P., Introduction to the theory of oscillations, 2nd ed., M., 1964; Gorelik G.S., Oscillations and waves, Introduction to acoustics, radiophysics and optics, 2nd ed. M., 1959.

Wikipedia

Resonance

Resonance- a phenomenon in which the amplitude of forced oscillations has a maximum at a certain value of the frequency of the driving force. Often this value is close to the frequency of natural oscillations, in fact it may coincide, but this is not always the case and is not the cause of resonance.

As a result of resonance at a certain frequency of the driving force, the oscillatory system turns out to be especially responsive to the action of this force. The degree of responsiveness in the theory of oscillations is described by a quantity called the quality factor. With the help of resonance, even very weak periodic oscillations can be isolated and/or amplified.

The phenomenon of resonance was first described by Galileo Galilei in 1602 in works devoted to the study of pendulums and musical strings.

Examples of the use of the word resonance in literature.

The instability of the universe can excite self-oscillations of nearby plot lines, which arises resonance, then the system collapses and.

There he continued his work on the study of physical phenomena known in science as the Saebeck and Peltier effects, under conditions of double in-phase piezoelectric resonance, discovered by him during his postgraduate studies and described in detail in his Ph.D. thesis.

If from resonance If the building collapses, then this five-beat gait can destroy Style.

The stock market crash immediately had an international impact resonance: Within a few days, most European markets, including the usually resilient Swiss market, suffered even greater losses than Wall Street.

The structure is swarming with electricians who watch as mechanics spray a layer of conductive fiber onto the shiny walls of the tower from the inside, installing insulating tubes, waveguides, frequency converters, luminous flux meters, optical communications equipment, focal plane locators, neutron activation rods, Mössbauer absorbers, multichannel pulse amplitude analyzers, nuclear amplifiers, voltage converters, cryostats, pulse repeaters, resistance bridges, optical prisms, torsion testers, all kinds of sensors, demagnetizers, collimators, magnetic cells resonance, thermocouple amplifiers, reflector accelerators, proton storage devices and much, much more, in strict accordance with the plan located in the computer memory and including for each device the floor number and coordinates on the block diagram.

Special radiations penetrating the baths cause resonance vibrations of deuterium atoms and body microstructures, ensuring the preservation of all body functions.

I believe that these books will continue to carry us along in a mysterious resonance with the works of Klossowski - another major and exceptional name.

There is no benefit from a discovered agent, but many obstacles are foreseen, and it is easier to get rid of him, if only to avoid possible incriminating conversations with the general public. resonance.

The divine gift of a deep and powerful mind, the awareness of whose presence came in youth, endowed with the genius of spiritual guidance, in resonance with whom the whole world found itself, and an artistic genius, for which you probably can’t even find words to define - incomparable, and at the same time - external everyday prosperity, a talented and worthy family, numerous - and all this is rare majestic, exhaustive, and in this in the sense that it is also harmonious.

Tangled in a web of wires, like a pin in a woman’s loose hair, a new paramagnetic installation swayed rhythmically in the wind. resonance.

Copwillem and others acoustic electronic and nuclear magnetic resonances have now been discovered in many crystals containing paramagnetic impurities.

Proximity to the stern teacher occupying the top position and the correct complete resonance in a beneficial second position makes this position quite happy.

Of course, the relationship with Mikhail, like all polygamous sexual desires, was resonance meetings in a past life with different persons, lost and met again in the current reality.

Even the character of my book, which is now coming to an end, changed as a result of the fascinating adventure of trying to divert a lava flow: fascinating technical details, huge social resonance this operation, finally, the incredible interest that this project aroused in me personally, all this has not gone anywhere over the past five months, while I was writing the second half of my book, and what I had previously intended to talk about in the last six chapters has melted away behind the bluish haze curling over the lava flows.

The desire of a noble driller got so noisy resonance, that it was decided to arrange a public display of her labor achievements.

Resonance is the phenomenon of a sharp increase in the amplitude of forced oscillations, which occurs when the frequency of the external influence approaches certain values (resonance frequencies) determined by the properties of the system. An increase in amplitude is only a consequence of resonance, and the reason is the coincidence of the external (exciting) frequency with the internal (natural) frequency of the oscillatory system. Using the phenomenon of resonance, even very weak periodic oscillations can be isolated and/or amplified. Resonance is a phenomenon that at a certain frequency of the driving force the oscillatory system is especially responsive to the action of this force.

Every mechanical elastic system has its own vibration frequency. If any force throws this system out of equilibrium and then ceases to act, the system will oscillate around its equilibrium position for some time. The frequency of these oscillations is called the natural frequency of oscillations of the system. The rate of its attenuation depends on elastic properties and mass, on friction forces and does not depend on the force that caused the vibrations.

If the force that brings the mechanical system out of balance changes with a frequency equal to the frequency of the natural frequency of oscillations, then the deformation of one period will be superimposed by the deformation of the next period and the system will sway with an ever-increasing amplitude, theoretically ad infinitum. Naturally, the structure will not be able to withstand such an ever-increasing deformation and will collapse.

The coincidence of the frequency of natural oscillations with the frequency of change of the electrodynamic force is called mechanical resonance.

Full resonance is observed when the frequency of force oscillations exactly coincides with the frequency of natural vibrations of the structure and equal positive and negative amplitudes, partial resonance - when the frequencies do not completely coincide and unequal amplitudes.

To avoid fur resonance it is necessary that the frequency of natural vibrations of the structure differs from the frequency of change of the electrodynamic force. It is better when the frequency of natural vibrations lies below the frequency of change in force. The selection of the required frequency of natural oscillations can be done in various ways. For tires, for example, by changing the free span length

When, when the frequency of the variable component of the electric force is close to the natural frequency of mechanical vibrations, even with relatively small forces, destruction of the apparatus due to resonance phenomena is possible.

Tires under the influence of EDF perform forced vibrations in the form of standing waves. If the frequency of free vibrations is above 200 Hz, then the forces are calculated for the static mode without taking into account resonance.

If the frequency of free vibrations of the tire during design, they strive to exclude the possibility of resonance by choosing the length of the free span of the tire.

With flexible tire mounting, the natural frequency of mechanical vibrations is reduced. The EDF energy is partially spent on deformation of current-carrying parts, and partially on moving them and the associated flexible fasteners. At the same time fur. The stresses in the tire material are reduced