What is mechanical impact on the phone? Mechanical properties of solids
Case 1
Case 2
B- Reaction without energy dissipation
C- Primary action
D- Opposite reaction with energy dissipation
In case 2, the connective tissue, thanks to the elastic element present in it, allows it to “absorb” the shock and distribute it widely over the surface.
This property is called passive protection, is extremely effective, even if it sometimes becomes a double-edged sword. In cases of lashing, due to the energy accumulated in the fluid masses of the body tissues, the damage appears later.
“...and if this energy were not dissipated by the own liquid masses of fascial tissue and the consequences of a blow from a whip, a push or an injury appeared immediately, what damage would be caused to the body?”
There is only one answer: of course, much heavier!
Example: a knife blade tears tissue and creates a cut wound only when applied from the sharpened side; Using the blunt side may result in chafing, swelling, and skin reaction, but not true organic damage; the only difference between the two situations is the surface area affected. The larger the area over which the traumatic impact extends, the less serious it will be. biological damage caused by injury.
The second phase of the protective role follows the first and consists of distributing the applied impact force through a continuous fascial system.
The force exerted on the body leads to the concentration of kinetic energy at the point of impact, causing powerful damaging consequences. The continuity of connective tissue prevents large concentrations of kinetic energy; it is redistributed through tissue links and then dissipated through a number of factors associated with the resumption of movement and functional adaptation, both fascial and general organic, in which kinetic energy is converted into thermal, electrical, etc., preventing the formation of a large amount of potential energy. This second phase is referred to as active protection.
“Biological damage” is a strategy that the fascial system operates to prevent the accumulation of kinetic energy unexpectedly received in such a short time that the body is unable to tolerate and redistribute it (physics teaches that energy cannot be destroyed, but is transferred to other forms).
Osteopathy with its fascial techniques has proven to be an effective tool for neutralizing such situations, facilitating the redistribution of kinetic energy through increasing dissipation and reducing the potential destructive power.
The role of fascia in coordination of movements
Fascia and aponeuroses are involved in coordinating the movements of both muscles and internal organs, separating muscle structures by membranes and ensuring that groups capable of contraction aimed at performing a similar role (synergistic) can work simultaneously to perform the same function.
Each membrane and muscle bed is aided in the performance of its functions by the ability of the connective membrane to support the totality of body parts. The nerve structures contained in each bed are in close mechanical relationship with the tissues that are supposed to stimulate. The role of nerves is carried out through neuromuscular fibers, Golgi tendon apparatus, Pacinian corpuscles and Ruffini organs.
Ruffini endings
Located in the articular capsules and adjacent areas; are responsible for muscle contraction, which, together with subsequent movement, changes the tension of the capsule. Tireless structures are called upon during movement so that it can be carried out in a smooth manner, without jerking. In addition to allowing you to maintain the position, the direction of movement is noted.
Golgi endings
Structures of slow adaptation, for a long time“assimilate” the information sent to them. They are located in ligaments attached to the joints and supply information regardless of the level of muscle contraction in such a way as to inform the body about the position of the joints, moment by moment, regardless of muscle activity.
Corpuscles of Pacini
Found in supra-articular connective tissue; quickly adapt and inform the central nervous system regarding the degree of acceleration of the movement being performed (acceleration receptor).
Muscle spindle
Regulates muscle tone. The location of the spindles as they attach to the skeletal muscle (tendon portion), parallel to the muscle fibers. While the spiral-ring ending quickly responds to the slightest change in muscle length, the flowery ending for balance provides information only after significant changes in muscle length. The muscle spindle is a “length comparison unit” that can return information for a long time to each stimulation.
Inside the spindle there are thin interspindle fibers that change its sensitivity; they can change without any real variation in the length of the muscle through a special afferent gamma controlled by the fibers themselves.
Golgi tendon receptors
They reflect muscle tension more than its length. If an organ is overloaded, it can use them to stop muscle activity and thereby avoid the risk of damage; this factor determines muscle relaxation.
Trigger points (trigger circuit, vibrator) are localized areas of great pain and increased resistance; acupressure of these points often provokes a contraction/grouping of muscles which, if held, causes pain in the targeted areas.
We are talking about signal posts that provide constant feedback from the central nervous system and higher centers regarding the instantaneous states of the tissue in which they are located. Their modulation can be caused by both mental influence and changes in the chemical composition of the blood.
Chains
The neuromuscular complex contained in the connective tissue and in direct contact with it allows for direct synergistic participation when muscles are attached to the aponeurosis, and indirect synergistic participation when muscles are attached to bone.
The concept of the “chain of muscle tension”, introduced by osteopathy and then picked up and expanded by postural gymnastics, finds its application in the fascial concept.
The function of the guarantor of coordination of movements performed by connective tissue arises from its connections with the nervous system (thanks to the purely mechanical effect exerted on the nervous component and its sensitivity to tension); In addition to distinguishing movement, intensity, force, the spindle is able to activate the higher nervous system and develop new functioning patterns. Often this kind of adaptation goes beyond physiology in the compensations involved by the body, aimed at eliminating any kind of force that can cause pain.
If we consider our posture as a constant oscillation of gaining and losing balance, with the goal of maintaining an upright body position, it becomes understandable why, even in the presence of slight anomalies, our balancing system must make adjustments of great precision to maintain both a static posture (upright posture) , and dynamic (movement).
When applied with force, the fascial component of our body adapts to the situation, masking and “silencing” the primary source of the problem in such a way as to cancel the nervous impact caused by the situation of discomfort or pain.
This fact allows only the last compensation made by the body to manifest itself, and hence pain symptom which, if eliminated without suppressing the root cause of the dysfunction, will persistently be caused again by the original problem.
The symptom of pain is the last signal of a series of adaptations introduced by the increasing compensatory ability of the connective tissue, changing the physiological circuit, which are “silent” until the most recent adaptation in the chain can no longer be compensated.
Conflicting information
Korr (1976) once again emphasized the importance of the bone marrow, which contains a large number of“pattern of activity” of muscles. The brain operates by producing complex movements that depend on the activation of muscle chains rather than individual muscles. For this purpose, programmed models are used, “stored in reserve” in the trunk and bone marrow, which are modified into an infinite variety of even more complex models and enrich the “warehouse” with these new derivatives.
Thus, each type of activity is modified, improved and “corrected” by appropriate feedback, constantly emanating from the muscles, tendons, joints (their connective tissue component) involved in movement.
GAS and LAS
English abbreviation for General Adaptation Syndrome ( G.A.S.) and local adaptation syndrome (LAS).
General adaptation syndrome, SOA, consists of an alarm reaction, a phase of resistance (adaptation), a phase of exhaustion (failed adaptation) and covers the entire body. Local adaptation syndrome, SMA, manifests itself in almost the same sequence, but in a limited area of the body.
Seyle (1976) called stress a nonspecific element that causes disease. Describing the relationship between the syndrome of general and local adaptation, he especially emphasized the importance of connective tissue.
Stress contributes to the creation of adaptation models that are specific to each organism and to each type of force. In response to stress, homeostatic self-normalizing mechanisms are activated.
If the state of anxiety is prolonged and repeated, processes of protective adaptation arise, leading to long-term changes that can become chronic.
By palpating neuromusculoskeletal changes, one can gain insight into the body's attempts to adapt to accumulated stress over time; the result will be a confusing picture of tense, contracted, compacted, overworked and, finally, fibrotic tissues (Chaitow, 1979).
It is important to understand that due to prolonged stress of the postural type (determined by the position of the body), physical and mechanical, some areas of the body make so much compensatory and adaptive efforts that structural changes appear that can develop into pathology.
In most cases, the combination of physical and emotional stress alters neuromusculoskeletal structures to such an extent that it causes a number of identifiable physical abnormalities. Compensatory attempts by these structures will in turn generate new stress factors; This may result in pain, joint restrictions, and general malaise, such as fatigue.
In the process of chronic adaptation to biomechanical and psychogenic stress, chain reactions associated with compensatory modifications of soft tissues develop (Lewitt, 1992). These adaptations are always detrimental to the body's optimal functioning and are the source of ever-increasing functional disorder (physiological changes).
Sequence of responses to stress
In the case of a prolonged increase in muscle tone, the following occurs:
n retention of catabolic products and edema
n local lack of oxygen (related to tissue needs) and subsequent ischemia
n maintaining or increasing increased functional tone
n chronic inflammation or irritation
n stimulation of sensitizers of nervous structures and the development of increased reactivity (hyperreactivity)
n activation of macrophages for increased vascularization and fibroblast activity
n fibrosis with reduction/shortening of the connective tissue component.
Along the continuity of the fascia throughout the body, any local overstrain can be reflected and negatively affect distant structures supported and attached by the fascia itself (nerves, muscles, lymphatic and blood vessels). As a result, the following may appear:
n changes in elastic tissues (muscles) with chronic reactive hypertension and subsequent fibrosis
n inhibition of antagonistic muscles
n chain reactions in which postural muscles shorten and phasic muscles weaken
n ischemia and pain caused by prolonged muscle tension
n biomechanical changes, incoordination with joint restriction and imbalance, fascial retraction
n the appearance of areas with increased reactivity of neurological structures (facilitation areas) in the paraspinal areas and inside the muscles (trigger points)
n energy consumption to maintain hypertension and, as a consequence, general fatigue
n constant Feedback impulses from the central nervous system, psychogenic alarm signals with an inability to adequately relax areas with increased tone
n biologically unreplaceable functional patterns caused by chronic musculoskeletal problems and pain.
The effectiveness of osteopathy lies in the fact that it works backwards in restoring the symptom of pain to identify the primary cause, directly influencing which opens the way to its elimination. Thus, there will be a return to the physiological norm of the tension parameters, which will also imply - but not only - the disappearance of the symptom of pain.
The fascial technique makes it easier to find the root cause compared to the traditional one. With subtle palpation, it is not difficult to follow the direction of tension in the fascia and get to the true origin of the problem... especially in cases where the doctor cannot prove the correctness of the symptomatology based on the patient's pain zone.
SOLUTION
In the name Russian Federation
The court composed of: Magistrate Judge of Judicial District No. 44 of the Central District of the city of Bratsk, Irkutsk Region, Zaugolnikova E.V.,
under secretary Lyashenko N.G.,
with the participation of plaintiff N.A. Shereshkova,
in the absence of a representative,
representative of the defendant,
having considered in open court a civil case on a claim in the interests of Shereshkova for the protection of consumer rights
U S T A N O V I L:
(hereinafter - carrying out, in accordance with Article of the Law of the Russian Federation "On the Protection of Consumer Rights", the protection of the rights and legitimate interests of individual consumers, filed a statement of claim in the interests of Shereshkova for the protection of consumer rights, indicating in support of the claim that on February 12 2016, Shereshkova applied, who indicated that on May 26, 2015 she purchased, which she insured from a representative of the insurer (TIN) on May 26, 2015. When concluding the insurance contract, N.A. Shereshkova was issued an insurance policy, which is confirmation of the insurance contract for conditions and in accordance with the “Rules for Insurance of Electronic Equipment” approved by Order No. 209-od dated July 31, 2014. In accordance with the policy, N.A. Shereshkova, in the event of an insured event, is the beneficiary.
On July 18, 2015, as a result of unintentional actions, the phone received external damage to the display module (screen) of the phone, which resulted in the fact that it did not display information, but displayed spots of “rainbow” colors, and there was also a very thin crack in the glass of the display module, which is shown in the photograph sent by N. A. Shereshkova to To determine the damage and the cost of repairs, N. A. Shereshkova contacted an authorized service center where diagnostics were carried out on August 18, 2015 (work completion certificate No. 055124 dated August 18, 2015. ), for which Shereshkova N.A. paid 450 rubles, after which a technical conclusion was issued that the display module needed to be replaced and the cost of repair work, taking into account the cost of spare parts, amounted to 5950 rubles. This amount was paid by N.A. Shereshkova. to an authorized service center. After replacing the display module, the phone was intact and working. That is, N.A. Shereshkova, as the policyholder, in accordance with Article 962 of the Civil Code of the Russian Federation, upon the occurrence of an insured event provided for in the property insurance contract, took reasonable and accessible measures under the circumstances to reduce possible losses. Shereshkova N.A. took measures to pre-trial resolve the dispute, she sent a statement to the insurer about the occurrence of an insured event. Attached to the letter was technical report No. 684 issued in as well as a photo of the phone, an application for the occurrence of an insured event (the application form established by the policyholder was attached to the policy), as well as copies of other documents confirming the existence of mechanical damage telephone and payment for repairs. In November 2015, a letter dated November 6, 2015 No. 07/02-08/49-02-05/30934 “On the refusal to pay insurance compensation in case No. MM NFL - 15 - 20841” was received. In December 2015, N.A. Shereshkova sent a claim to which at the end of January 2016 she received a response dated January 18, 2016 No. 07/02-08/31-03-02/1201 “On repeated refusal to pay insurance compensation for the payment case MM-NFL-15-20841”, on the basis that the photograph does not show external mechanical damage, and “in accordance with clause 3.4 of the Special Conditions, damage in the form of scratches, chips and other cosmetic damage, as well as internal breakdowns without external damage."
In accordance with clause 3.2.1.8.1. Special conditions, “mechanical impact” must be understood external influence objects on the surface of the insured property." Of course, the impact of the phone on the floor, accidentally falling from the table, should be considered an external mechanical impact on the surface of the insured phone, therefore, in accordance with clause 3.2.1.8. Special conditions, the incident is an insured event, since the insured property (telephone) suffered damage “in the form of damage/destruction as a result of mechanical impact.” External and internal damage to the phone was received simultaneously, under the circumstances described above, and thus the insured property (phone) suffered damage in the form of external and internal damage as a result of mechanical impact, which, in accordance with Appendix No. 5 to the order dated September 26, 2012 No. 283 -od Special conditions of insurance for insurance 3.2.1.8.1 is an insured event. At the same time, the insurer’s references to the fact that the crack is not visible in the photograph are unfounded, since in accordance with the policy of N.A. Shereshkova was not obliged to send any photographs to the Insurer at all. In accordance with Art. Section III. Judges, bodies, officials authorized to consider cases of administrative offenses > Chapter 23. Judges, bodies, officials authorized to consider cases of administrative offenses > Article 23.49. The federal executive body exercising federal state supervision in the field of consumer rights protection" target="_blank">23 Federal Law "On the Protection of Consumer Rights" asks to recover in favor of the plaintiff N.A. Shereshkov a penalty in the amount of 1,728 rubles, as well as moral damages in in the amount of 3,000 rubles, based on the fact that by concluding an insurance contract, the plaintiff expected to be able to quickly and effectively repair the phone she purchased in the event of its breakdown during an insured event. The illegal refusal of insurance payment caused her moral suffering, since she realized that the insurer he actually deceived her, and by concluding the contract he only intended to receive an insurance premium from her without the intention of fulfilling the insurance contract in the future, also the cost of the telephone and the amount of the insurance premium are significant for N.A. Shereshkova. In a situation where the insurer refused an insurance payment, the insurance paid by the consumer the bonus only increased the expenses of N.A. Shereshkova. to purchase a telephone without receiving any benefit for her, which she expected when concluding an insurance contract. In addition, paying for the cost of repairs is essential for N.A. Shereshkova, since she could not not repair the phone - a child should have a phone in modern conditions, but N.A. Shereshkova I hoped to receive the insurance amount and reimburse my expenses for repairs. Having been illegally denied insurance coverage and not receiving compensation for her phone repair expenses, the plaintiff was forced to reduce her expenses for other vital purposes, including limiting herself to purchasing food for herself and her family. Thus, the illegal refusal of insurance payment resulted in N.A. Shereshkova moral suffering, and the defendant is obliged to compensate for the moral damage caused. Guided by Art. , Art. Art. , the Law of the Russian Federation “On the Protection of Consumer Rights” asks the court to recover in favor of the consumer Shereshkova: 5950 (five thousand nine hundred fifty) rubles to return the cost of repairing the insured phone she paid, 450 rubles for diagnostics, 3000 rubles - compensation for moral damage; a penalty in the amount of 1,728 rubles, which is calculated as follows: 1,200 rubles (amount of insurance premium) ? 1% ? 144 days (delay period from November 6, 2015 - the moment of refusal of insurance payment and until March 23, 2016 - the day of filing the statement of claim) = 1,728 rubles, and also to collect from the defendant in favor of Shereshkova a fine provided for in Part 6 of Art. Law of the Russian Federation “On the Protection of Consumer Rights”.
The person acting on the basis of a power of attorney did not appear at the court hearing and submitted an application to consider the case in his absence.
At the court hearing, plaintiff Shereshkova supported her claims and explained to the court that on May 26, 2015, when purchasing a phone, she entered into an insurance agreement with a representative of the insurer. When concluding the insurance contract, she was issued an insurance policy. On July 18, 2015, when she visited her daughter, where the latter worked as a counselor, the phone was accidentally dropped from the table, resulting in external damage to the display. Externally, there was a very thin crack on the display, since the phone has durable glass, but the phone itself stopped displaying information and displayed spots of “rainbow” colors. Since there was no office of the insurance company, she called the defendant by phone and reported the occurrence of an insured event. She was recommended to contact the service to determine the nature of the damage and the cost of repairs, and therefore, she contacted an authorized service center where diagnostics were carried out on August 18, 2015, for which the plaintiff paid 450 rubles, after which technical report No. 684 was issued that the display module needed to be replaced and the cost of repair work, taking into account the cost of spare parts, would be 5,950 rubles. On September 14, she sent the defendant a conclusion and other documents by e-mail; further correspondence was carried out by e-mail; she was additionally asked for photographs of the phone, after which she was denied payment of insurance compensation, since the photo of the phone sent by her to the insurance company did not show any external damage to the display fixed. In the photographs, the crack is really not very visible, since it was thin, but a technical report was sent to confirm the presence of damage. She believes that she was unreasonably denied payment of insurance compensation. Requests that the stated claims be satisfied in full. She also explained that initially a technical conclusion was issued that the repair of the display module amounted to 5,950 rubles, but later the repair cost her 5,050 rubles.
The representative of the defendant, acting on the basis of a power of attorney, did not appear at the court hearing, having been properly notified of the time and place of the hearing of the case, submitted a response to the statement of claim, in which he indicated that the insurance agreement dated May 26, 2015, concluded between and Shereshkova N .A., was concluded on the terms and in accordance with the “Rules for Insurance of Electronic Equipment” dated July 31, 2014 and the Special Insurance Conditions for the insurance product “Advantage for Equipment//Portable+”. In accordance with paragraph 1 of Art. the conditions under which an insurance contract is concluded may be determined in the standard rules of insurance of the corresponding type, adopted, approved or approved by the insurer or an association of insurers (insurance rules). In accordance with the entry made in the Policy, with the Rules and Conditions, the policyholder N.A. Shereshkova was acquainted and agreed. After the plaintiff filed a statement about the occurrence of an event that had signs of an insurance event, it was decided to refuse to pay the insurance compensation, about which an official refusal was sent to her dated January 18, 2016 No. 07/02-08/31-03-02/1201 , on the basis of articles of the Civil Code of the Russian Federation. In accordance with paragraphs. “f” clause 3.4 of the Special Conditions, damage in the form of: scratches, chips and other cosmetic damage to the insured property that does not affect its performance is not an insured event; internal breakdowns without external damage, including breakdowns resulting from manufacturer defects. The fact that the phone has currently been repaired due to the stated event does not allow us to objectively consider the plaintiff’s stated claims, including conducting an examination. There are no declared damages on the photographic materials, and the malfunctions declared by the company are not relative and unconditional evidence that the insured object was in a faulty condition. Insurance contract, in accordance with Art. . It was concluded between two parties, the terms of the contract were satisfactory to the plaintiff and, before the events of July 18, 2015, were not disputed or declared invalid. reviewed the application of the policyholder N.A. Shereshkova. within the framework of the insurance contract, in accordance with Art. according to the submitted documents. According to paragraph 1 of Art. , when concluding a property insurance contract between the plaintiff and an agreement was reached on certain property or other property interest that is the object of insurance, on the nature of the event in the event of the occurrence of which insurance is carried out (insured event), on the validity period of the contract. Thus, according to clause 4 of the insurance contract, the object of insurance was determined to be a telephone; insurance risks, according to clause 5 of the contract, are defined as: fire, explosion, lightning strike, exposure to liquid, natural disasters, exposure to foreign objects, exposure as a result of an accident, robbery, robbery, hooliganism, theft; amount of insurance compensation - 11490.0 rubles; The contract period is 1 year (clause 7 of the contract). In accordance with paragraph 1 of Art. Law of the Russian Federation of November 27, 1992; 4015-1 “On the organization of insurance business in the Russian Federation”, insurance risk is the expected event in the event of the occurrence of which insurance is carried out. An event considered as an insurance risk must have signs of probability and randomness of its occurrence. Accordingly, according to the requirements stated by the plaintiff, it did not take on additional risks. With regard to the damage specified in the claim, the insured did not provide the Insurance Company with documents confirming the claimed event. According to clause 7 of the Insurance Conditions, the policyholder, upon the occurrence of an event that has signs of an insured event, provides documents that must contain information that allows one to unambiguously identify the insured device (Mark, model, IMEI/Serial). According to clause 6.1.5 of the Insurance Conditions, at the request of the insurer, the policyholder submits the documents necessary to confirm the fact and reasons for the occurrence of the insured event and determine the amount of damage caused to the insured property (in accordance with clause 7 of the Conditions), photographs of the damaged property. Taking into account the presented arguments, if the claims of N.A. Shereshekova are satisfied, she asks to apply the consequences of Art. , when collecting a fine from the amount satisfied by the court. In order to prevent unjust enrichment on the part of the policyholder, in accordance with clause 8.5 of the Insurance Conditions, complete loss of the insured property is recognized if the total cost of restoration repairs is at least 80% of the cost of the insured property. Thus, to date, the plaintiff has not made a decision to abandon the insurance object. He asks that the stated demands be denied in full.
Having listened to the plaintiff N.A. Shereshkova, having studied the presented objections of the defendant’s representative, and having examined the evidence presented, the court comes to the following conclusion.
The court does not see any legal grounds for reducing this fine.
DECIDED:
The claims are partially satisfied.
To recover from Shereshkova 5,050 rubles - towards the return of the paid cost of repairing the insured phone, 450 rubles - for diagnostics in the amount of 450 rubles, a penalty in the amount of 1,200 rubles, compensation for moral damage in the amount of 1,000 rubles
Refuse to satisfy the claims for recovery of the cost of repairs in the amount of 900 rubles and a penalty in the amount of 528 rubles.
To collect a fine for failure to comply with the voluntary procedure for satisfying consumer requirements in favor of Shereshkova in the amount of 1925 rubles, in favor of 1925 rubles
To collect from the state duty to the budget of the municipal formation of the city of the region in the amount of 700 rubles.
The decision can be appealed to the Bratsk City Court of the Irkutsk Region through the magistrate judge of judicial district No. 44 of the Central District of the city of Bratsk, Irkutsk Region within a month.
An application for drawing up a reasoned court decision may be filed within three days from the date of announcement of the operative part of the court decision, if the persons participating in the case and their representatives were present at the court hearing; within fifteen days from the date of announcement of the operative part of the court decision, if the persons participating in the case and their representatives were not present at the court hearing
Judicial practice on the application of Art. 333 Civil Code of the Russian Federation
We will consider the resistance of instrumentation to mechanical influences using the example of aviation instruments and devices, since they operate under the most severe conditions of the complex influence of all types of mechanical factors.
The main sources of external dynamic influences on aircraft instrumentation (AU) are the aircraft on which it is installed and the environment. The excitation of dynamic influences from the aircraft is called kinematic, and from the internal devices of the aircraft - force. Force impacts most often result from the operation of power supply units, air conditioning devices, hydraulic systems, fuel supply, etc., i.e. electromechanical devices, with reciprocating moving masses or unbalanced rotating rotors.
Mechanical impacts include: linear overloads, vibrations, shocks.
During transmission from the source to the AUV and its elements, external mechanical influences are transformed - the amplitude-frequency characteristics of vibrations, the amplitude and duration of shock pulses change; transient oscillatory processes occur that accompany the effects of long-term linear loads.
G-force is the ratio of the effective acceleration to the acceleration of gravity. Linear overloads, with the exception of short-term ones, cannot be eliminated or weakened. Therefore, the operability of structures is ensured by increasing the rigidity and strength of the elements, which, as a rule, leads to an increase in the mass of AUV structures.
AUV vibration is understood as mechanical vibrations of its elements or the structure as a whole. Vibration can be periodic or random. In turn, periodic vibration is divided into harmonic and polyharmonic, and random vibration into stationary, non-stationary, narrowband and broadband.
Vibration is usually characterized by vibration displacement, vibration velocity and vibration acceleration.
Vibration displacement during harmonic vibration is defined as
Where Z- vibration displacement amplitude; - vibration frequency.
Vibration velocity and vibration acceleration are found as a result of differentiation (5.1):
Vibration acceleration during harmonic vibration is ahead in phase of vibration displacement by an angle, vibration velocity by an angle.
Amplitudes of vibration displacement Z, vibration velocity , vibration acceleration and angular frequency of vibration are the main characteristics of harmonic vibration. However, in addition to them, harmonic vibration can be characterized by vibration overload
. (5.2)
If in (5.2) the amplitude of vibration displacement is expressed in mm, and the acceleration of gravity in , then the relationship for vibration overload can be written in the form , Where -
circular vibration frequency.
Polyharmonic or complex periodic vibration can be represented as a sum of harmonic components.
Random vibration is characterized by the fact that its parameters (amplitude of vibration displacement, frequency, etc.) change randomly over time. It can be stationary and non-stationary. In the case of stationary random vibration, the mathematical expectation of vibration displacement is zero, the mathematical expectation of vibration velocity and vibration acceleration is constant. In the case of non-stationary vibrations, the statistical characteristics are not constant.
In addition to vibration, the structure may be subject to shock impacts arising during operation, transportation, installation, etc. During an impact, structural elements experience loads for a short period of time, accelerations reach large values and can lead to damage to the elements. The intensity of the impact depends on the shape, amplitude and duration of the shock pulse.
The shape of the shock pulse is determined by the dependence of shock acceleration on time (Fig. 5.1). When analyzing shock effects, the real shape of the shock pulse is replaced by a simpler one, for example, rectangular, triangular, half-sinusoidal.
The amplitude of the shock pulse is taken to be the maximum acceleration upon impact. The duration of the impact is the time interval during which the shock pulse operates.
The consequence of the impact is damped vibrations occurring in the structural elements. Therefore, in practice, there is a need to protect AUV structures from shocks and vibrations simultaneously, since in real operating conditions structures are often subjected to complex mechanical influences, which should be reflected
when designing protective equipment.
AUV structural elements are characterized by their mechanical resonant frequencies, which vary widely depending on the mass and rigidity of the fastening of the components. In all cases, the formation of a mechanical oscillatory system in the load field must not be allowed - this applies to circuit boards, panels, casings, mounting wires and other parts of the AUV structure.
The load field refers to the mechanical loads of the system caused by fluctuations of various frequencies and amplitudes during testing, installation, transportation and operation.
As a result of mechanical influences, reversible and irreversible changes can occur in the AUV structural elements.
Reversible changes are typical for AUV electrical and radio products, which leads to instability and deterioration in the quality of functioning of the equipment. Factors causing reversible changes can be combined into the following groups depending on the physics of the processes occurring in the structure:
Deformations in active and passive components, leading to changes in their parameters;
Violations of electrical contacts in connectors and permanent connections, causing a change in the ohmic resistance of the contacts;
Changes in the parameters of electric, magnetic and electromagnetic fields, which can lead to a violation of the conditions of electromagnetic compatibility in the structure.
Irreversible changes are characteristic of AUV structural elements, are associated with a violation of strength conditions and are manifested in mechanical destruction of the elements. Elements that are pre-loaded during assembly and electrical installation (bolts,
screws, rivets, welds with residual thermal stresses, bulk conductors with excessive tension, etc.).
Irreversible changes that occur in the structural elements of AUVs under mechanical influences include fatigue failure.
Fatigue is the process of gradual accumulation of damage in the material of a part under the influence of alternating stresses. The mechanism of this process is associated with the structural heterogeneity of the material (individual grains are not the same in shape and size, are differently oriented in space, have inclusions, structural defects). As a result of this heterogeneity, shears arise in individual unfavorably oriented grains (crystals) under variable stresses, the boundaries of which expand over time, move to other grains and, covering an increasingly wider area, develop into a fatigue crack. The fatigue strength of materials depends on the magnitude and nature of stress changes and on the number of loading cycles.
AUV structures operating under mechanical stress must meet the requirements of strength and stability. Strength (vibration and impact resistance) to mechanical factors means the ability of structures to perform functions and maintain parameter values within the limits established by standards after exposure to mechanical factors.
Resistance (vibration and impact resistance) to mechanical factors is understood as the ability of a structure to perform specified functions and maintain its parameters within the limits established by standards during exposure to mechanical factors.
External friction, mechanical resistance that occurs in the plane of contact of two contacting bodies during their relative movement. Resistance force F, directed oppositely to the movement of a given body, is called the friction force acting on this body. T.v. - a dissipative process, accompanied by the release of heat, electrification of bodies, their destruction, etc.
There are T. v. sliding and rolling. The first characteristic is the sliding friction coefficient f c is a dimensionless quantity equal to the ratio of the friction force to the normal load; characteristic of the second - rolling friction coefficient f k represents the ratio of rolling friction torque to normal load. External conditions (load, speed, roughness, temperature, lubrication) affect the value of temperature. no less than the nature of rubbing bodies, changing it several times.
Sliding friction. If the component of the force applied to the body, lying in the plane of contact of two bodies, is insufficient to cause the given body to slide relative to the other, then the resulting friction force is called incomplete friction force (section O.A. on rice. ); it is caused by small (~ 1 µm) partially reversible movements in the contact zone, the magnitude of which is proportional to the applied force and changes as the latter increases from 0 to a certain maximum value (point A on rice. ), called the static friction force; these movements are called pre-displacements. After the applied force exceeds a critical value, the preliminary displacement turns into sliding, and the force T. in. decreases slightly (point A 1) and ceases to depend on movement (friction force of movement).
Due to the waviness and roughness of each of the surfaces, the contact of two solid bodies occurs only in separate “spots” concentrated on the ridges of the protrusions. The size of the spots depends on the nature of the bodies and the conditions of heating. More rigid protrusions are embedded in the deformable counterbody, forming single spots of real contact on which adhesion forces arise (adhesion, chemical bonds, mutual diffusion, etc.). As a result of running-in, the contact spots are “stretched” in the direction of movement. The diameter of the equivalent area of the contact spot ranges from 1 to 50 µm depending on the nature of the surface, the type of treatment and the heating mode. When sliding, these spots tilt at a certain angle to the direction of movement, the material moves apart and is crushed by the sliding unevenness, and the adhesion spots formed from surface films covering the solid body, called bridges, are continuously destroyed (cut off) and formed again. In these spots, stresses are realized only several times less than the theoretical strength of the material. Resistance to material displacement during shear depends on the dimensionless characteristic h/R- depth relations h introduction of a single irregularity, modeled by a spherical segment, to its radius R. This ratio determines the mechanical component of the T. force.
For the most part, the described shape change is elastic and energy dissipation is due to losses in hysteresis. In the contact spots, intermolecular interaction forces arise, the losses to overcome which are estimated by the dimensionless characteristic t/s s, where t is the shear resistance of the molecular bond, s s is the yield strength of the base. Molecular shear resistance t = t 0 +b P r, where t 0 is the strength of the bridge in the absence of compressive load, P r is the actual pressure on the contact spot, b is the bridge hardening coefficient. Each contact spot (the so-called frictional connection) exists only for a limited time, since the protrusion leaves the interaction. The lifespan of a friction connection is an important characteristic, since it determines the temperature developing during heating, wear resistance, etc. Thus, the process of heating. is a dual process - on the one hand, it is associated with the dissipation of energy due to the overcoming of molecular bonds, on the other, with the shape change of the surface layer of the material by embedded irregularities.
General coefficient of T.v. determined by the sum of the mechanical and molecular components
Where TO- coefficient associated with the location of the protrusions in height, a g - hysteresis loss coefficient. It follows from the equation that the T. coefficient. depending on the pressure at constant roughness or on the roughness at constant pressure it passes through a minimum. During the running-in of friction pairs, a roughness is established that corresponds to the minimum T. coefficient. For effective operation of a friction pair, it is essential that the surface layer of a solid body has less shear resistance than the deeper layers. This is achieved by using various liquid lubricants. In this case, the rubbing bodies are separated by a layer of liquid or gas, in which the volumetric properties of these media appear and the laws of fluid friction, characterized by the absence of static friction, come into force. Sometimes it is necessary to have the surface layer of the body itself weakened; this is achieved by using surfactants (lubricant additives), soft metal coatings, polymers, or creating protective films with reduced shear strength.
Depending on the nature of the deformation of the surface layer, they are distinguished. during elastic and plastic contacting and during microcutting. Under certain conditions, depending on the load and mechanical properties of each friction pair, T.V. goes into internal friction, which is characterized by the absence of a speed jump when moving from one body to another. The load at which T. in. violated for a given friction pair is called the external friction threshold.
Rolling friction. The values of the rolling friction force are very small compared to the sliding friction forces. Rolling friction is caused by: a) losses due to elastic hysteresis associated with compression of the material under load in front of the rolling body; b) the cost of work for re-deforming the material when forming a roller in front of the rolling body; c) overcoming clutch bridges. If the size of the contact spot is sufficiently large, slipping occurs in the contact zone, leading to the sliding friction already discussed above. At high rolling speeds, comparable to the rate of propagation of deformation in the body, the resistance to rolling increases sharply, and then it is more advantageous to switch to sliding friction.
Friction control by selecting friction pairs, unit designs and their correct operation is the topic of a new technical science called tribology.
Lit.: Deryagin B.V., What is friction?, 2nd ed., M., 1963; Kragelsky I.V., Friction and wear, 2nd ed., M., 1968; Dyachkov A.K., Friction, wear and lubrication in machines, M., 1958; Friction of polymers, M., 1972; Bowden F. and Tabor D., Friction and lubrication of solids, trans. from English, M., 1968.
I. V. Kragelsky.
![](https://i2.wp.com/eduspb.ru/photo/enc/82511-i008-pictures-001-295069393.jpg)
The value of the friction force depending on the relative displacement of the rubbing bodies during shear turning into sliding.
It is well known that the physical and mechanical properties of a material, including concrete, are largely determined by its structure. By the concept of concrete structure, we agree to understand the totality of the “macrostructure” created by the arrangement of aggregates, and the “microstructure” of cement stone, including the contact zone “cement stone - aggregate”.
The structure of concrete is a complex function of the physical, chemical, and mechanical factors applied to it.
The “MACROstructure” of concrete is formed as a result of external mechanical influence on all its components during the preparation and compaction of the concrete mixture. By and large, the perfection of the macrostructure of concrete reflects the recipe proportions of concrete (the ratio between binder, aggregates and water) as well as the degree of uniformity of their distribution among themselves (mixing efficiency).
At the same time, the “MICROstructure” of concrete is formed both under the influence of external mechanical influence and under the influence of colloidal-chemical and physico-chemical processes occurring in the binder (dispersion of cement grains, their dissolution, followed by coagulation and crystallization, etc.)
It is characteristic that changes over time in all the basic physical and mechanical properties of concrete (strength, elasticity, shrinkage, creep, density) are mostly due to the kinetics of changes in the characteristics of the “microstructure” of concrete. We can control it (with varying degrees of efficiency) both at the level of the initial structure formation of cement stone, and in the process of the initial formation of contact fields between the binder and aggregates. In practical terms, “control” of the microstructure of cement stone is possible through chemical (various types of additives and modifiers in concrete), mechanical (external mechanical influence on the initial stages of cement hydration) and thermal (heat and humidity treatment).
As one of the most effective ways modification of concrete parameters both at the “microstructure” and at the “macrostructure” level is the vibration effect on the concrete mixture at the stage of its preparation - vibration activation, vibration mixing. Even more effective is the mechanochemical control of the microstructure of cement stone, when the mechanical action is superimposed on solid-phase reactions (mechanical activation) and (or) direct chemical action of chemical modifiers (surfactants, electrolytes, polymers).
10.2.4.1 Intensification of cement hydration processes during vibration exposure.
If we examine microsections of cement stone prepared by conventional mixing of components (Fig) and those prepared in a vibrating mixer (Fig), the difference is clearly visible. In the latter case, the microstructure of the cement stone is more dispersed - the crystals of the new formations are much smaller. Accordingly, the structure of the cement stone is more homogeneous, there are less internal stresses and local microdefects, which significantly reduces the likelihood of occurrence of fracture sites - as a result, the strength of such cement stone will be higher.
Figure Microphotograph of a cement stone preparation prepared by manually mixing cement with water (dark zones are unreacted cement grains).
Figure Microphotograph of a cement stone preparation prepared using vibratory mixing of cement with water (dark zones are unreacted cement grains).
Numerous experiments confirm that under the influence of external mechanical influence (in this case vibration), the processes of cement hydration are significantly accelerated (see Table)
Values of the degree of hydration and compressive strength during hardening of vibration-treated cement stone.
Characteristics of cement stone |
Degree of hydration (%) |
Compressive strength (kg/cm2) |
||||||
1 day |
3 days |
7 days |
28 days |
1 day |
3 days |
7 days |
28 days |
|
Cement M-600, W/C=0.30, without vibration (control) |
10.1 |
31.5 |
211.0 |
|||||
Cement M-600, W/C=0.30, vibration during laying - 6 minutes |
10.2 |
12.6 |
56.0 |
298.0 |
||||
Cement M-500, W/C=0.26, without vibration (control) |
11.0 |
12.1 |
12.8 |
125.0 |
180.0 |
|||
Cement M-500, W/C=0.26, vibration during laying – 6 minutes |
11.1 |
12.5 |
13.3 |
132.0 |
255.0 |
|||
Cement M-500, W/C=0.26, preliminary vibration activation – 10 minutes + vibration during laying – 6 minutes |
12.2 |
13.4 |
13.6 |
216.0 |
450.0 |
Note: Brotsna Cement Plant
10.2.4.2 Empirical prediction of the characteristics of vibration-activated concrete compared to conventional concrete.
Based on the study of the influence of vibration influences on the process of concrete hardening, a characteristic phenomenon is observed: the absolute difference in strength between the vibration-treated and control samples (prepared in the traditional way, without vibration influence), which is formed at the beginning of the structure formation of the cement stone, remains close to constant during the further course of hardening.
As numerous studies have shown, the reason for the increased strength of concrete subjected to vibration is the compaction of coagulation structures. The reason for the constancy of the strength increase during all time periods of concrete hardening is the same intensity of crystallization of both vibration-treated and control samples.
The fact of a constant increase in strength opens up a wonderful opportunity to determine the absolute values of the strength of vibration-treated samples during hardening and, in connection with this, the effectiveness of vibration treatment, if there is data on changes in the strength of control samples and the initial difference in their strengths is known. From a practical point of view, it becomes possible to use data from 12 – 24 hour tests. determine the final strength by recalculating the data of the control (not vibration-activated) hardening composition under similar conditions with a coefficient close to 1.08. (The increasing coefficient was determined experimentally - it reflects the fact that vibration treatment not only helps to improve coagulation structures and accelerate the initial structure formation, but also causes some intensification and more complete development of structure formation processes at a later date.
The calculation can be carried out using the following simple formula:
Rvibro = 1.08 * (Rcontrol + Rdelta)
Rvibro – calculated strength of a vibration-activated sample for a given hardening duration
Rcontrol – experimental strength of a control non-vibration activated sample for the same hardening period
Rdelta is the absolute difference in strength between vibration-treated and control samples at the age of 12–24 hours.
10.3 Activated and special cements, as an alternative to high-strength, fast-hardening and extra-fast-hardening Portland cements.
10.3.1 Theoretical and practical features of the production of high-strength and fast-hardening cements from special clinkers.
In accordance with the areas of application in concrete technology, it seems logical to divide Portland cement into the following classes: ordinary, high-strength, high-strength (HPTs), rapid-hardening (BTC), extra-fast-hardening (OBTC).
Portland cement grade M-400 is called ordinary. The class of high-strength cements includes cements of the M-500 brand. The high-strength class includes cements of grades M-550 and M-600 (GOST 10178-76), and the fast-hardening class includes all cements with a compressive strength of at least 25.0 MPa after 3 days of hardening.
The first experimental batches of Portland cement in the USSR with activity, according to modern estimates, of about 55.0 MPa were produced by VNIITs at the Volsky cement plants back in 1938.
Later, in the mid-50s, the Belgorod Cement Plant produced the first pilot batch of cement corresponding in activity to the current M-600 brand. When producing pilot batches, very strict and difficult to achieve technological standards were used, which did not allow the regular production of such cements.
To resolve these technological difficulties, a solution was proposed, the essence of which boiled down to a whole complex of rather complex measures, which, nevertheless, made it possible to optimize all technological stages - from optimizing the mineralogical composition of special cements to the features of their grinding and storage.
As a result, teams of cement plants, together with narrowly applied research institutes, produced experimental and then industrial batches and began constant industrial production of high-strength cement, first with an activity of 55.0 MPa (grade M-700 according to GOST 970 - 61) at the Bryansk and Oktyabr plants ( Novorossiysk group), Zdolbunovsky. Subsequently, the production of cements with an activity of 60.0 MPa was also mastered at the Zdolbunovsky, Bolshevik (Volskaya group), Belgorod, Bryansk, Abvrosievsky, and Teplozersk plants.
The first experimental batches of quick-hardening cement were produced in the USSR in the 30s under the leadership of V. N. Jung and S. M. Royak. Its industrial production began in 1955 to meet the needs of the newly created precast concrete industry, and the initial strength standards were lower than modern ones - approximately 10.0 - 12.0 MPa after 1 day of normal curing and 20.0 MPa after 3 days of curing using current test methods.
The effectiveness of using high-strength and fast-hardening cements (HPC and BTC) in the construction and construction industry is due to the possibility of increasing the grade of concrete, reducing the material intensity of reinforced concrete products and structures, reducing the technological cycle of their production, installation, installation under working load, and, finally, increasing the load-bearing capacity and reliability of structures, buildings and structures. These benefits increase sharply with an increase in HCV activity to 70.0 – 80.0 MPa.
In addition, entire areas of production of building materials are entirely dependent on the supply of special cements. For example, the production of foam concrete becomes economically feasible and highly profitable only when using fast-hardening cements of the M-500 and M-600 grades.
10.3.1.1 Mineralogical features of high-strength and fast-hardening cements.
To obtain high-strength and fast-hardening cements, only raw material mixtures with maximum reactivity are suitable, depending on the physico-chemical nature of the raw materials, the chemical composition and dispersion of the mixtures. The physico-chemical nature of the raw materials is the totality of the geological and mineralogical characteristics of the main components - lime and silicate - determining their chemical activity and resistance to crushing.
Not all raw materials used for the production of ordinary cements are suitable for the production of high-strength and fast-hardening cements. In some regions, for example Central Asia, the production of such cements is generally impossible - the raw materials do not allow it.
In addition to the peculiarities of the selection of raw materials, high-strength and fast-hardening cements are also distinguished by certain difficulties during their firing - special alite crystals (tricalcium silicate - C3S) of a strictly defined shape and size with a rhombohedral crystal structure should prevail in the clinker composition.
10.3.1.2 The influence of particle size distribution on the activity of HCV and BTC.
Cement is produced by grinding specially burned raw materials - clinker. Like any fired product that has undergone melting-crystallization processes, cement clinker has a certain submicrostructure. Therefore, the granulometric composition of clinker after grinding in ball mills mainly depends on the nature of the internal crystalline structure of the clinker - during the grinding process, destruction primarily occurs in the least strong areas of the clinker’s crystalline structure. This provision determines that our influence on the grain composition of the grinding products of drum mills with ball and cylinder loading can only be modifying.
Table 10.3.1.2-1
Granulometric composition of cements, fast-hardening, high-strength and high-strength
(C3S - 60-65%, C3A - 3-7%)
(modification of alite in clinker) |
Type and brand of cement |
Specific surface area, cm2/g |
||
less than 5 microns |
5 – 30 µm |
|||
Zdolbunovsky (R-C3S) |
BTC-500 |
2500 – 3200 |
12 – 18 |
40 – 50 |
BTC-550 |
3200 – 3700 |
15 – 21 |
45 – 60 |
|
OBTC-550 |
3500 – 3800 |
18 – 23 |
50 – 65 |
|
VPTs-600 |
4300 – 6100 |
25 – 40 |
55 – 70 |
|
VPTs-600 |
4000 – 4500 |
21 – 27 |
58 – 68 |
|
Novorossiysk (M-C3S) |
VPTs-550 |
3200 – 3700 |
17 – 20 |
40 – 45 |
OBTC-550 |
3800 – 4000 |
19 – 23 |
42 – 55 |
|
VPTs-600 |
4500 – 4700 |
25 – 28 |
55 – 60 |
|
Bryansk (M-C3S) |
VPTs-550 |
3200 – 3700 |
8 – 12 |
65 – 71 |
VPTs-600 |
3600 – 4000 |
18 – 20 |
54 – 65 |
|
Volsky (M-C3S) |
VPTs-600 |
3900 — 4230 |
14 — 23 |
48 — 65 |
Note: All cements from the Zdolbunovsky plant are obtained by grinding in a closed cycle, the rest in an open cycle.
OBTC – extra-fast-hardening cement Rday=20.0 MPa
Thus, when finely grinding clinker, it is impossible to avoid the formation of a small fraction (less than 5 microns) in an amount of 12.5% of half the mass of the middle fraction (5 - 30 microns). In the absence of separation, a large fraction (more than 30 microns) will inevitably remain in an amount of 25–50% of the mass of the middle fraction. All other things being equal, cements made from fine-crystalline clinkers contain 1.5 times less coarse fraction than cements made from coarse-crystalline clinkers. The granulometric composition of high-strength cements (Table) is characterized by an increased content of fractions 5 - 30 and less than 5 microns, and fast-hardening ones - fractions less than 5 microns. The linear correlation coefficient between the content of the fraction less than 5 microns and the strength of cement after 1 day of hardening is 0.77 (therefore this fraction is preferable in BTC), and between the amount of the middle fraction and the activity of cement at 28 days of age is 0.68
The smaller size of crystalline blocks of alite compared to belite is a likely reason for the concentration of alite in fine fractions of cement. Thus, with 55% alite in the original clinker and a specific cement surface of 3000 cm2/g, the fraction less than 5 microns contains an average of 60% elite, and when the specific surface of cement increases to 5000 cm2/g, it already contains 75-80% alite. Thus, at the grinding stage, a significant change in the chemical and mineralogical composition of cement occurs, when different fractions of cement consist of essentially different minerals!
The depletion of the middle fraction in alite cannot be considered a positive factor. On the contrary, enriching the fine fraction with belite would help activate its hardening. This is one of the most important problems of cement technology. This distribution of minerals is achieved in the cements of the Belgorod and Balakleysky plants (they have a largely similar raw material base) thanks to the dendritic structure of belite, which “reinforces” the intermediate substance of the clinker and increases its fragility. Large quantity Belite is concentrated here in the fine fraction, and alita in the middle fraction of cement, which explains the positive properties of cement from the Belgorod and Balakleya plants, well known to builders - a rapid increase in strength, in particular during steaming, high crack resistance, reduced shrinkage and creep.
10.3.1.3 Relationship between the dynamics of hydration of cements from special clinkers and their grain composition.
Research has shown that when the grinding fineness of cement increases from 2000 cm2/g to 6000 cm2/g (with optimal gypsum content for each level of dispersion), the degree of hydration (based on the content of non-evaporating water) and strength at 1 - 3 days of age increase, and at 28-day increase only to certain limits, and then decrease significantly. The optimal dispersion of cement grinding depends on the mineralogical characteristics of the clinker, and primarily on the predominance of certain alite modifications in it.
In some cases, with an increase in the specific surface area of cement from 2000 to 3000 cm2/g, the content of the fraction less than 5 µm generally decreases, which can cause a decrease in hydration and a lack of increase in the strength of cement with a simultaneous increase in its dispersity.
The presence of a maximum dispersion of cement, exceeding which leads to a slowdown in hydration, is a relatively “young” discovery, which, nevertheless, explains many of the paradoxes encountered by modern researchers who, in an attempt to obtain fast-hardening cements, are one-sidedly limited to its additional grinding.
This paradox can be explained by the influence of two opposing factors - an increase in the reaction surface of cement particles interacting with water, and an increase in the screening ability of hydrate formations, which, surrounding cement particles, prevent the access of water. At W/C = 0.4, the degree of hydration of the fine fraction after 1 day is 100%, the middle fraction is 20%, the large fraction has practically not yet hydrated.
After 3 days, all the small and already about half of all medium and large fractions will also be hydrated. And only after a month from 60 to 90 percent of all cement will be hydrated.
This “stepwise” hydration of cement of different fractions forms a mechanism (first predicted at the tip of a pen by G. Kühl) in which the contact zones between the hydration products of the medium and fine fractions are “glued together” by the hydration products of the fine fraction (don’t hit too hard - as I managed, I explained ).
All this indicates the intensifying influence of the fine fraction on the hydration of the remaining cement fractions. Experiments on mixing cements of different dispersion showed that the optimal ratio of fine and medium fractions in HPC with rhombohedral alite is from 1:4.8 to 1:5.1. Without a small fraction, HCV cannot be obtained in principle!
10.3.1.4 Basic technological schemes for the production of high-strength and fast-hardening cements.
The main technological scheme for the production of high-strength and fast-hardening cements is based on the use of specially selected components of raw sludge used for clinker firing. Extraction of raw materials for BTC and HCV is a very troublesome and expensive undertaking, because Its selection at existing raw material quarries of cement plants has to be carried out selectively. So at the Bryansk havod they reject the sandy part of the clay and chalk from karst sinkholes. At the Zdolbunovsky plant - clay containing more than 20% quartz grains, at the Voskresensky plant - inclusions of silicified chalk (bruises), at the Novorossiysk plant - marls containing glauconite and phosphorites, etc.
The production of BTC and HCV very strictly limits the production of raw sludge - much more careful averaging is required (this entails an increase in the capacity of sludge basins) and finer grinding of raw materials to particles less than 40 microns. At one time in the USSR, only the Belgorod plant was able to fully comply with the requirements of technological regulations for the preparation of sludge for burning clinker for special cements.
There are no particular technical difficulties at the stage of clinker firing in rotary kilns - the required thermal parameters of firing are well within the characteristics of modern kilns. And a number of domestic cement plants (in particular Balakleysky, Kamenets-Podolsky, Stary Oskolsky) at one time quite successfully set their kilns to modes that ensured the mass production of high-activity clinker from which cement grades M-600 and higher were subsequently obtained. But due to such an abnormal and undesigned operating mode (the kilns were nevertheless designed for the production of ordinary cements), it was necessary to increase fuel consumption for firing (increase the temperature in the sintering zone) and artificially reduce the productivity of the kilns by 10-15% (to stabilize the zone sintering).
Features of the production technology of HPV and BTC also impose significant differences from the traditional production scheme for ordinary cements at the grinding stage. The main feature of the grinding mode of BTC and, especially, HPC is the use of ball loading in ball mills with the minimum possible average diameter of the balls. This, in turn, makes it almost impossible to use powerful and high-performance large-diameter drum mills for grinding BTC and HPC (or significantly reduce their rotation speed from the design one).
All together, this determines the fact that even modern mills operating in a closed cycle with separation, when grinding BTC and HPC, show productivity 40–50% less than when grinding ordinary cements.
Moreover, all the expensive tricks for producing high-quality fast-hardening and high-strength cements can be completely eliminated in just a few months of storage. Even in bituminized five-layer bags, cement during storage loses from 5 to 15 percent of activity per month!!!
Therefore, everything taken together (briefly given above) at all times determined the extremely “unfriendly” attitude of cement factories even to the very idea of establishing a massive and constant production of BTC and HCV. And only when such high-quality cements were required for the most important facilities, primarily military infrastructure and medium-sized engineering, could the “steady hand of the Party” push cement plants to achieve such achievements.
Is it any wonder that in the absence of this “steady hand”, BTC and HCV also completely disappeared from the domestic cement market - the objective economic prerequisites for their production have not yet developed - it is cheaper to export such cements if the need arises.
(It is quite possible that the rise in price of cement in Russia will create a more favorable situation when the massive use of BTC and HCV becomes economically feasible - and then the domestic construction market will again, like a quarter of a century ago, with enthusiastic aspiration and admiration, “relish” these enchanting properties of any factory abbreviation technologist – BTC, OBTC, VPTs.)
(to be continued)