Research On The Dynamical Analysis Methods For Equipment Maintenance Systems

The equipment maintenance system is the complex system of systems, whichcomprises many maintenance elements, such as materials, manpowers, information andladders of management, etc, to carry out maintenance actions. With the evolution ofoperational theories and operational styles and the development of equipmenttechnologies, the structures and functional modes of equipment maintenance systemshave been transforming profoundly, which require that maintenance actions should becarried out scientifically and supported accurately. The equipment maintenance systemin nature, however, is stochastic, dynamic, correlative and evolutive, which brings greatchallengestoanalyze,design,integrateandcontrolit.Process information is the basic means to control it. Comprehending and graspingthe dynamical behaviors of the equipment maintenance systems, i.e. the operationallaws, is the foundation of analyzing, designing, integrating and controlling it. Thus, thedynamical analysis methods naturally become the suitable framework and tools forstudyingdynamicalbehaviorsoftheequipmentmaintenancesystem.To carry out maintenance scientifically and support accurately, the followingissues must be solved: (1) to execute necessary maintenances by grasping theequipment's degradation and failure mechanism well and truly, (2) to carry outmaintenance at proper occasions and with the optimal number of times by optimizingthe equipment maintenance policy, (3) to respond to the maintenance requirementstimely and support them correspondingly by allocating maintenance resourcesreasonably, (4) to integrate maintenance systems orderly to form systematic effects byplanningthemaintenanceconstituents'deploymentglobally.Centering on these issues, this thesis studies the equipment maintenance systemfromtheviewpointofdynamics,andthemajorworkscanbesummarizedasfollows:(1)The problem of acquiring the laws of degradation and failure of equipmentswiththeirstatemonitoringdataisstudiedfrom theviewpointofdynamicsidentification.A group of dynamical equations based on stochastic Ito equation are put forward tocharacterize the change process of state monitoring data. The maximum entropyestimationalgorithmisderivedtoestimatetheprobabilitydensityfunctionoftherateofincrements of state monitoring data, which is used to determine the dynamical propertyof the equipment deterioration process. The iterative recursive prediction error methodisprovidedfortheparametersidentificationoftheequipmentdeteriorationprocess.Andthe deterioration states of the equipment are estimated with Gaussian kernel basedK-means clustering algorithm and the law of equipment deterioration is approximatedwith finite phase type distribution by using the expectation maximization algorithm.With all these equations and methods above, a dynamical framework for analyzing the equipment degradation process is built, which has been applied successfully to analyzetheweardeteriorationprocessofsomeengine.(2)The problem of controlling maintenance occasions and maintenance numbersis studied from the viewpoint of the coupling in the usage and maintenance of theequipment. Extending the maintenance states over the state space of the equipmentdeterioration process, the effects of various maintenance actions on the usage of theequipment and the state transition of its maintenance process are analyzed. Aiming atthe single and complex failure modes, the densityevolution method and matrix analyticmethod are put forward respectively to build the optimal criteria of maintenanceoccasions and maintenance numbers, both of which have been successfully used tooptimize the preventive maintenance cycle and maintenance numbers for the wear ofsomeengine.(3)The system dynamics method is used to study the dynamical behavior modesof the equipment maintenance system, which result from the interaction among theequipment working process, maintenance polices and the constraints of maintenanceresources.Basedonthestatetransitionoftheequipmentusageandmaintenanceprocess,the basic causality and feedback structure in the equipment maintenance system areanalyzed. The system dynamics model of the maintenance system is established forsome engine, and the behavior modes and the influencing factors of the equipmentmaintenancesystemareexplored.(4) To evaluate the equipment maintenance systems integration performance, thenetwork analysis method is adopted to analyze the integration modes and measure thesystematic performance of maintenance systems. By way of analyzing the basicelements of the equipment maintenance systems, its elementary model and itsperformancemeasures areset up.Theeffect ofthegrowthofmaintenanceelements andtheir interactions on the maintenance system performance is studied from the viewpointof maintenance information utilization rate, and the best integration mode and possibleintegration patterns of equipment maintenancesystems are determined.Based on the study of dynamical analysis methods of the equipment maintenancesystem, the state evolution rules of the equipment deterioration and failure process canbe mastered and the maintenance can be performed pertinently and necessarily; theeffects of maintenance actions on the degradation of the equipment captured and themaintenance moment and maintenance number of times controlled by rule and line; thegeneration laws of maintenance requirements understood and the maintenance resourcesrequirements answered in time and executed accurately; the impact of the deploymentof maintenance elements on the performance of maintenance system caught on and themaintenance elements configured and deployed best. Thereby, the study of dynamicalanalysis methods lays the foundation of optimizing and controlling the equipmentmaintenance process and maintenance system, the results of which could be used to guide the analysis, design, integration and control of the equipment maintenancesystem.