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Dmitriy Yu.Kobzov, Lhanag Dorligsuren, Deleg Dorjbal
DIALECTICAL APPROACH TO THE INSIGHT INTO ENGINEERING OBJECTS EVOLUTION
Engineering object functioning is inevitably accompanied by negative changes in their structural parameters, following them are functional, technico-economic ones and those of accompanying processes which are interrelated among them in a definite way (Fig.1).
It is desirable to represent the whole range of these continuous microevents by the model of structure and cause and effect relationship of the object - MSCER (Fig.2). It is the most suitable logical description of simple objects such as hydraulic drive hydrounits of road & building construction machinery. These models are worked out on the basis of the analysis of structural scheme of the object under investigation and conditions of its work having regard to the conformities with laws of structural parameters degradation. So the MSCER in Fig.2 contains 13 levels: 1 — an engineering object (EO); 2 — constructive elements groups of EO; 3 — EO constructive elements proper; 4 — structural parameters of object elements; 5 — EO elements characteristic defects and damages; 6 — boundaries of the greatest evolution of EO technical state at a maximum qualitative or quantitative change of a particular structural parameter; 7 — defect or damage signs
Fig.1. The scheme of technical object parameters change in the process of its operation; SP - structural parameters; FP - functional parameters; TEP -technico-economic parameters: APP -accompanying processes parameters; ^ - cause and effect relationship.
(symptoms); 8 — diagnostic parameters; 9 — their controllable components; 10 — the matrix of interconnection (Fig.3); 11 — EO characteristic qualitative peculiarities, degradation of which as it is operated is connected with evolution of the technical state; 12 — specific weights of object failures caused by its concrete constructive elements defects; 13 — and finally prices of each of them [1,2].
It is when and due to irreversible changes of all the mentioned parameters that degradation of engineering object state which is accompanied by discrete macroevents of technical state types and variations change take place. As it is known [3] variations of object structural parameters values come about within it under the influence of external factors and due to interaction of elements when the object is operated. These values change from predetermined ones to the limiting ones, the result of which is a similar change of values of its technical and economic functional parameters etc. And this change is invariably accompanied by the transition of an object from one complex of technical state into another one, that is from one variety of technical state into another one as is show in Fig.4. It goes without saying that evolution of object technical state types occurs within the limits of operative ( + 0), and inoperative (-0), fit for work (F + ) to unfit (-F), from the state of regular functioning ( + RF) to that of irregular one (-RF). There is no doubt that: an operative object is always fit for work while the object fit for work may be both operative and inoperative; an inoperative object may be both fit for work and unfit for work or failed; the failed object is always inoperative; the inoperative object but fit for work may be characterized by both regular functioning and irregular one; the operative fit for work object is always characterized only by regular functioning. From this it follows that the evolution of any object technical state as it is operated occurs from complex 1 of technical state types which is characterized by working order, fitness for work and regular functioning ( + 0 + F + RF) through
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Fig.2. MSCER the hydrocylinder as an example).
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Fig.4. The scheme of EO technical state type evolution as it is operated and their interaction with a particular technical state variation: ^^ - the
direction of type evolution;--the boundary of a
particular object technical state variation; ^ - the interaction of types within a variation; ^ - the direction of state variation evolution.
variabilities 2 (-0 + F + RF) and 3 (-0 + F-RF) to complex 4 of state types which is characterized by unfitness for work (-0-F). In a special case not every stage of technical development is necessary and the appearance of the latter is not desirable. The intensity of evolution stage change having prevailing significance for working out the algorithm and prognostic governing rules increases with its operation as the object elements accumulate defects, that is because of continuing qualitative and quantitative change of its structural parameters and is mainly determined by constant deteriorating interaction conditions of elements within the object and the increase of external factors influence on it.
The above-named complex of events is recommended to represent in the form of the graph of cause and effect relationship of evolution of structural, technological, functional parameters as well as those of accompanying processes and loading operation conditions as a result of engineering object maintenance (Fig.5). It is desirable to develop such a graph on the basis of experimental investigation results synthesis, theoretical research, gained experience and intuition, but with obligatory analytical description of all the revealed cause and effect relationship at the final stage.
The structure of such a graph includes several typical levels.
First level (I) — the level reflecting object development evolution: Hhc — hydrocylinder power: Ihc — its work intensity.
Second level (II) — the level of its main structural varied and planned parameters: Z — rod stroke; Dv D2 — piston and rod diameters; P — working fluid pressure.
Third level (III) — the level of structural and technological features: B0 — technological
deviations from rod and casing rectilinearity; C0,
C0 — clearance in sealing conjugations; D0 —
hydraulic cylinder support bearing diameter; Qhc
— hydraulic cylinder weight; Phc — rod force; Ghc
— hydrocylinder length; V0 — support bearing
rotation.
Fourth level (IV) — the level of functional parameters: QDhc — dynamic loads; e°s — static
eccentricity of support load application; e°K —
kinematic eccentricity of support load application; y a — hydrocylinder deflection
because of clearance in its sealed conjugation; y p -
hydrocylinder deflection because of technological deviation rod and casing rectilinearity; yy - the same as in previous but as a
result of working distortion; y5 - hydrocylinder deflection because of diametric deformation under casing pressure; y D - hydrocylinder
deflection under the influence of dynamic load; yP - hydrocylinder deflection from longitudinal loading; yQ - hydrocylinder deflection from
transverse loading; yR — hydrocylinder
deflection from support friction; y£ — total
hydrocylinder deflection.
Fifth level (V) — the level of loading parameters: Mk — bending moment from support friction; MKS — bending moment from support
loads eccentric application; MQ - bending
moment from transverse static and dynamic loads; M py — bending moment from deformed
hydrocylinder longitudinal loading;
R0 — hydrocylinder support reactions; R13, R24 — reactions in hydrocylinder sealed conjugation; SO - operative tensions.
Sixth level (VI) — the level of typical parameters and those of accompanying processes; * — above mentioned characteristics
Fig.6. The N-dimensional space of possible modification of engineering object basic structural parameters for a particular working process, operation and maintenance conditions.
increment; A0, A13, A24 — complex characteristics of seizing and setting of hydrocylinder conjugation elements; C0 — support bearing clearance; C13, C24 — clearances between packer and sealed surface; E13, E24 — complex characteristics of packer material resilient properties relaxation; I0, I13, I24 — hydrcylinder element wear intensity; K0 — support bearing
coefficient of friction; K
hc
hydrocylinder
mechanical coefficient; Kchc — working fluid
contamination degree; Pf3, P^ - packer contact
pressure; S'., S". — fatigue stress and yield stress
limits; VS - packer integrity; WQ - support bearing wear; W™, W2Sf - packer wear; T0, T13, T24 -
temperature.
Seventh level (VII) — the level of object typical properties: L13, L24 — sealed conjugations pressurizing capacity (leakage); U2, U3-hydrocylinder supporting power (banding strain).
Eighth level (VIII) — the level of failure types: F' — parametric failure; F" — complete failure.
Ninth level (IX) — the level of object estimated features: RA — reliability; WA — workability.
All the typical graph points are connected by cause and effect relationships.
Getting in this way a full logical system of events it is necessary to reveal engineering object state criteria (i, j, ... n, etc.) which ultimate quantitative changes inevitably cause its state specified variety occurrence for the accepted level of reliability RA (Fig.6). We should aim on the one hand at minimizing their number and degree of mutual overlapping and on the other — at simultaneous increase of significance of every one of them and provision and embracing all the events by criteria complex.
Then it is necessary to relate them with scanning vector WA (Fig.6) in N-dimensional space of possible modification of engineering object basic structural parameters for a particular working process, operation and maintenance conditions. Established in the final analysis set of technical state criteria limiting values is the measure of the given
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УПРАВЛЕНИЕ В ТЕХНИЧЕСКИХ СИСТЕМАХ
quantitative-qualitative object definiteness within its scope it is workability with a specified reliability level and it can be changed in the direction of some general development trend according to principles primordial peculiar to it.
REFERENCES
1. KobzovD.Y., Martynenko O.P., GubanovV.G. There must be no alternative to the right choice of diagnostic parameters. Proceedings of the 2nd International Machinery Monitoring
& Diagnostics Conference & Exhibit, Los Angeles, California, 1990. PP.374-380. Kobzov D.Y. Diagnostics of Hydrocylinders of Single Bucket Excavators Working Equipment. Synopsis of thesis for doctor's degree. Leningrad, 1987. 22 p. Reliability and Effectiveness in Engineering. Reference book. In 10 vol. (Ed.B.: Avduevskiy V.C. etal.). Moscow, Machine-building, 1986. V.I: Methodology. Organization.
Terminology. Edited by Rembeza A. 224 p.
Носков С.И. УДК 330.115
ТОЧЕЧНАЯ ХАРАКТЕРИЗАЦИЯ МНОЖЕСТВА ПАРЕТО В ЛИНЕЙНОЙ МНОГОКРИТЕРИАЛЬНОЙ ЗАДАЧЕ
К числу классических в теории приня- задачи (1), (2) принято понимать так называе-тия решений относится многокритериальная мое множество Парето. Обозначим его через задача линейного программирования (МЛП), N с X .Решение х е N называется паретовским формальная постановка которой имеет вид: (недоминируемым, неулучшаемым), если его
нельзя улучшить по какому-то одному крите-Cx ^ max, (1) рию, не ухудшив значение хотя бы одного из
оставшихся. Или, формально,
xeX
X = | x eRn |Ax < b, x > o|. (2)
x e N ^ (Vy e X, y Ф x)-((Cy >Cx) л(3/ C y >Cx)),
Здесь, в отличие от обычной задачи ы ■ <■ ^
„ ,1Г„ „ где С - 1-ая строка (/-ыи критерии) матрицы С.
линеиного программирования (ЛИ), С — мат- т-г ^ т-г
^ г г * Проблеме построения множества Иа-
рица размерности l х и, а не вектор; А — матри-
рето в задаче МЛП посвящена обширная лите-
ца ограничений размерности т х п. Таким об- ратура. Вместе с тем, одной из лучших (если не разом, многокритериальная задача (1), (2)
предполагает максимизацию на многогранни-
лучшей) публикацией на эту тему является,
по-видимому, статья американских математике X не одного линеиного критерия, как в об- ков Р. к Уи и М. Zeleny [1]. Именно здесь при-
ычноизадаче(ЛИ),а I критериеводновремен- ведены хорошо теоретически обоснованные но.
методы построения множества паретовских Заметим, что от нормальнои формы вершин Мех е Ми всего множества Иарето.
/ Л \ /ГЛ\ V и 1 А
задачи(1), (2)легкопереитикканоническои. Для построения множества Мех в [1]
Ограничение х > 0, также легко обходится. представлен так называемый многокритери-
Как правило, традиционного реше- альныи симплекс-метод. Он основан на двух
ния задачи (1), (2) не существует, то есть отсу- основных теоремах, формулировки которых
мы приведем здесь без доказательства.
тствует точка х е X такая, что Сх > Су для всех у е X,у ф х. В случае, когда у лица, принимающего решения (ЛИР), отсутствует какая-либо Теорема 1 ([1]). априорная информация относительно сравни- Множество Nех связно.
тельнои важности критериев, под решением
