Process Reliability And Mission Disaster Assessment Modeling Study For A Spacecraft Launch Engineering

The reliability and disaster assessment of spacecraft launch which is in the finalstage of the construction of aerospace engineering plays an important role in avoidingengineering disaster. In recent years, the reliability of space products continues to beimproved，but the natural pioneering and complexity of aerospace engineering result indisasters from time to time. Moreover, the study of reliability and disaster assessment ofspacecraft launch engineering (SLE) is still under growth, and we have yet to seeconcrete results from the research for human, organization and process reliability.Therefor, comprehensive using recent research results from related disciplines,researching theory and method for the spacecraft launch engineering, establishingmodel with all-round combining symptoms of extreme events in order to effectivelyestimate the reliability and disaster in a SLE is viteal important in theory and reality.On the basis of the summary and analysis of relevant research results at home andabroad, considering the engineer practice background, associating the simulation data,this paper establishs and verifies the human reliability, the organization reliability, thescheduler reliability and the engineering disaster assessment model for SLE. The mainwork, contribution and conclusion are as follows:(1) There exist irreplaceable and compensatory facts in the discourse domain ofhuman reliability and organization reliability. The purpose of examining human andorganization reliability by the composition of state of irreplaceable and compensatoryfactors can be attained. Based on field data and knowledge on SLE practice, this paperdiscusses the factor space of human and organization reliability in SLE, and proposesthe method of the composition of state of irreplaceable and compensatory factors(CSICF), and establishes assessment models of human and organization reliability inSLE, and validates the effectiveness and feasibility of the proposed method through theworking team reliability assessment for the flight control command delivery activity inthe mission XL-51, and initially solves the methodological issues for how toquantitatively assess human and organization reliability in SLE.(2) From aerospace products into the launch site to the vehicle ignition, Changesabout the states of sub-processes present the Markov property and state transfer ratesonly relate to residence time of system in the state. Therefor, we can applying the modelof continuous-time Markov chain (CTMC) to simulate organization processes of a SLE.On the basis of the comprehensive study the mission reliability of aerospace productsand ground equipments and organization reliability, according to the constraintrelationship between sub-processes, this paper constructs the model of CTMC fororganization processes of SLE and gives the calculation method of the model parameters.Whereafter, the paper discusses the problems of how to compress the state space of multi-CTMC concurrency model by using bisimulation equivalence relation (BER), andpresents a model of how to calculate the reliability of the engineering organizationoverall process. Finally, through the X-51mission schedul analysis, the paper furtherillustrates that the model is of practical use and method of use.(3) Effective access and comprehensive utillization of disaster symptoms in SLEcan improve the accurancy of the disaster assessment and reduce the fuzziness of thedisaster forecast. According to the dependencies between systems in SLE, this paperdesigns failure dependency tree (FDT). And to take the FDT as a framework, the paperdiscusses the symptom information fusion method (SIFM) based on evidence theory,and studies the symptom network inference method (SNIM) by using Bayesian networkinference, and constructs the disaster assessment model of SLE. The SIFM based onevidence theory can make all kinds of partial, incomplete, uncertain disaster symptomsacquired by experts in different fields with different methods mutual compensation, toeliminate redundant, to reduce uncertainty. The SNIM based on Bayesian networkinference can effectively avoid the drawback that the SIFM easily leads to the minorityopinion being ignored. A combination of both can effectively guarantee the clear andcorrect result for disaster assessment in SLE. The case analysis for STS-51L disasterassessment verifies the effectiveness of disaster assessment model proposed by thispaper.