Modern man does not think of its existence, without the various mechanisms that simplify life and make it much safer.Any technique used primarily valued for their safety.This quality is largely derived from other properties - reliability.
What is it?How stands the term?And what does he really mean?Let's deal!
Determination
So reliability - is the ability of an object to maintain the desired properties and characteristics for a certain time interval.In addition, this feature emphasizes the ability to save all the set quality during transportation and / or severe extreme conditions.
fairness it should be noted that the reliability - a complex concept that can not be described in brief.In particular, in the technique of this definition is expanded to several concepts that are closely related to each other.Let's look at each of them.
about technical reliability
in the art may be deemed secure only the object that satisfies the requirements of just four or rather has features that must be traced to its characteristics and properties.To make it easier to understand this definition, we present a list of them:
- As we have said, the reliability - the ability to perform over a period of time constructively incorporated into the device functions.For example, the electric motor must consume a well-defined amount of energy and to provide the set speed of rotation.If you keep this theme, the power supply system is important for the ability to give the correct voltage, the value of which can fluctuate only in a strictly limited range.
- Performing job functions must also occur only in the technological limits that had been laid by the device manufacturer.For example, the engine is functioning in those environmental conditions that do not lead to its destruction.
- On the contrary, if you want a stable job in a dusty environment, the device must provide this for as long as possible time interval.Note that this and all of the above characteristics is required to reliably perform.
- object, among other things, must be capable of preserving all their technical characteristics, not only in working position, but in the state of rest.Thus, the motor vehicle must (subject to certain conditions) to be ready to start, even if the car in front of it stood in boxing for several months or even years.
Interim Conclusions
Thus, reliability - this is a very important quality of an object.It is in any case can neither oppose nor mixed with other qualitative terms.For example, a plant for cleaning industrial emissions can be very attractive in price, by its ability to trap particulates from the air to the maximum possible number.That's just no information on how long data can be stored characteristics, its purchase is very dangerous, and often entirely useless.
contrast, in the specifications of the device may be a mass of information about reliability, but not a single word about what exactly the characteristics it possesses.Thus, the definition of safety should include all of these items.
Some additions
Depending on the purpose of the object reliability - a synonym for reliability, maintainability, durability.It should be clearly understood that this quality is perceived by only taking into account the characteristics of the object itself.For example, if you take unrecoverable sensor in a sealed housing, then it will be the reliability of the ability to maintain its performance in a given period of time.Simply put, if this device will work without failure 12 months at an annual guarantee, it should be recognized as sufficiently reliable.
However, there are certain exceptions to such strict rules.Remember how we talked about the car, which is on conservation?In this case, reliability - is not synonymous with the word "reliability", which implies an immediate engine start, and the "longevity" and "maintainability".No one can guarantee that the engine will start immediately and will run without problems.
reliable powerplant guaranteed withstand storage (with more or less suitable conditions) and will be able to function after any maintenance activities.Thus, to ensure reliability - a list of the necessary measures, which are aimed at increasing the probability of failure, the smooth functioning of the equipment, complete systems and industrial complexes.
Most crucial is the ability of the device rose to its deadline of operation without serious damage and the need for maintenance.This applies especially to those subjects that need to be operated in extremely difficult conditions.
What should be guided by assessing the reliability of the site?
Typically, manufacturers are guided by GOST 27.002-89 "Reliability in the art. Concepts. Definitions", from which are derived almost all notions of safety, taken in the national technical and industrial sectors.However, this standard covers not all concepts, so sometimes we will make an explanation.
Just consider the types of reliability.Modern science suggests that there are only two:
- Resilience element of the object system.
- stability of the whole complex as a whole.
These concepts are not only related, but should flow logically from one another.And so we will consider this term, in general, a common understanding.
Basic concepts of reliability theory: object element and the system
object is called a kind of technical product that must be monitored, from design to delivery to the consumer.It should be remembered that under this definition includes not only individual components but also quite complex systems: machines, buildings, industrial buildings and complexes systems.
Thus, a system refers to a set of objects connected by some common feature, that it must carry out.Element as you might guess, is called a small, integral part of the object that has specific functions.From each element separately independent operation and operational reliability of the entire system in general.
All these concepts are quite relative, since they can be seen through each other.Thus, the object at some research may be considered by the system (as he himself is a collection of elements) and may be an independent element, if considered from the point of view of a large and remote working complex.
Simply put, it all depends on the scale that is required to be considered in studies.This is what says the theory of reliability, which is now long since emerged as an independent and very important scientific branch.
relationship of man and machine
People who work machine operators and production capacity are also separate elements of systems.They are connected with each other and with the mechanisms.Systems interact in real time.A sign of their integrity and reliability is a clear correlation of structural objects and elements to each other.
on the possible states of an object
should be noted that each object in a given time period can be in a certain state.It depends on the specific parameters of reliability.Let's list them:
- good condition.In this case, the object is fully consistent with all regulatory parameters, which are incorporated in a manufacturer.
- malfunction it is recognized when at least one of these parameters do not match the specifications.
- The health state of the object can perform all of its main functions, and the value indicators will be established within the technical standards.Keep in mind that a defective device can be started, but it can not be called workable, and its reliability will steadily decline until they become equal to zero.
- Unavailability - a condition in which the object does not meet the laid down in a technical specifications, and can not perform its functions.Reliability in this case a call is not in principle.
limit state reliability
when discussing the reliability of technical systems, of paramount importance the concept of a limiting condition.In short, the so-called situation in which further operation of the machine or the device becomes invalid and / or impossible.This condition occurs due to the failure or the occurrence of any serious defects, the tension of the material.Thus any attempt operation may end in failure, as the device is likely to falter and collapse.
Signs of a limiting condition set by the manufacturer, the information should be reflected in the attached object to the technical specifications.Every year there is a general increase in reliability due to greater technological processes of production, but all the data the manufacturer shall provide, upon request of the consumer.
What are the common signs of a limiting condition?
As we have said, there are two types of objects:
- called restores the element whose operation can be completely restored, and in standard conditions.
- Accordingly, the non-recoverable object is the one operation which is impossible to renew.Anyway, under standard conditions.
For each category, there are certain common features, which can confidently diagnose a limiting condition.Of course, the reliability of the technical system in this case will also be different if it (the system) consists of only one object, which is not amenable to recovery activities, the performance of its reliability will be zero.If an object can be repaired (or replaced by one that can not be repaired), indicators actually lead to the norm.
As for objects that can not be repaired, then the limiting condition for them comes at the very moment when the guarantee period is exhausted, or other resources, which was founded by the manufacturer.The same can be said about the development of the maximum allowable in which further operation of the device becomes unnecessarily dangerous.In some cases, the safety factor is calculated.The formula is quite simple it:
ki = li / lb
Let's find out the meaning of the variables:
- li - the absolute value of the failure rate;
- lb - component failure rate.
calculated failure rate
To do this, use the following equation:
l (i) = n (t) / (Nt * Dt)
- l (t) - the total number of failures.
- Nt - the average number of elements in the system.
- n (t) - the number of failures for a certain period of time.
- Dt - adopted as an axiom period of time in which you commit to the total number of problems with the system.
Important!Outside the absolute value of failure is taken from the specialized reference books.In every industry it is completely different, so bring a huge list of the pages of this material, we are not physically able to.
calculating the safety factor, you can easily find out about what is expected from the object.The figure is lower, the more reliable instrument should be recognized, a car or a house.
About recovered objects
As in the previous situation, the limit occurs when the continued operation simply becomes impossible or extremely impractical.In the latter case should take into account the totality of several factors:
- Maintaining object on the minimum safety and / or performance level it becomes impossible or too expensive.
- As a result, wear the device or machine came to such a state that it is easier and cheaper to buy the same item.
In some cases, the manufacturer considers that the limiting condition occurs at the moment when the totality of the accumulated problems can be corrected only by making major repairs.In principle, it is quite a reasonable approach, as it can prevent many serious trouble.Thus, synonymous with "reliability" - serviceability, maintainability.
should be remembered that during the operation the subject may have, and other conditions, which we now discuss.
transition facilities in various states during its operation
- damage - an event consisting in the infringement of serviceability of an object while maintaining its efficiency.
- Disclaimer - an event consisting in the malfunction of the object.
- failure criteria - distinguishing feature or set of such, according to a finding of failure.
- recovery - the process of detecting and eliminating failure (damage) in order to improve its capacity (serviceability).
Practical analysis of reliability
When experts are engaged in the analysis of the reliability of the object, machine or building, they become extremely important making the right decisions about what to do in case of failure.Assuming that the subject is theoretically restored, but under certain conditions it is not expedient repair and / or can not be wiser to translate it into the category can not be repaired.
Take, for example, weather satellite.During his land design, build and test it relates to recoverable objects.When placing into Earth orbit, the probability of repair tends to zero, and therefore the reliability of the success of the program.
Reliability intangible concepts
Earlier we told you that studying the theory of reliability when it comes to material objects: things, instruments, machinery, ships, aircraft, etc.But whether at least some of these concepts are used in more mundane view?How, for example, to know the reliability of the banks?After all, they do not have a manufacturer that would recommend to pick up your contribution after the occurrence of a deadline !?
In principle, a decision has, in this case, although the definition of reliability made by several other indicators.Let's list, on what criteria should pay attention first and foremost:
- structure of financial institutions, a summary of its founders.
- founding members of the commission.
- reviews, opinions, and the prescription for at least two to three years.In more recent information is better not to pay attention at all.
- main interest as a deposit, and loans.
- Providing bank guarantees.
First of all, you should pay attention to the founders.Some names immediately say knowledgeable people that communicate with the bank just not worth it.Always try to get to the truth: if the site or in the founding documents that are available in the public domain, no such information, refer to the list of organizations that somehow relate to this institution.If they are (even in the distant past) turned out to be implicated in financial scandals, it is better to look for the money over a safe place.
That's determined by the reliability of banks.If at least one item from the list of the above makes you wary and uncertainty, it is strongly advised not to use the services of this particular financial institution.
