Storage Reliability Degradation Test And Evaluation Technologe Of Aerospace Electromagnetic Relay

Aerospace electromagnetic relay (EMR) is one of the key electromechanicalcomponents used for signal transmission, load switching, circuit protection andcontrol and system isolation. To increase the weapon performance and meet theneed of “long-term storage, one shot”,24years storage life has been proposed insome weapon project. At present, concern for the storage reliability of AerospaceEMR is respectively light although it comes to the highly-dependable and long-lifeelectrical components. And the corresponding research still faces a series ofproblems, such as low level experiment and test detection, unclear law o fperformance parameters changing, ambiguous about failure mode and failuremechanism, and lack of effective evaluating and predicting means. Therefore, howto evaluate the storage reliability of aerospace EMR has become the importantsubject that demanding prompt solution at present.This dissertation with the background of “long-term storage, one shot” weaponequipment system and a type of widely used aerospace EMR as research object. Anew method for testing storage reliability is proposed by performance parametersdegradation. Based on the research of failure mechanism and the analysis ofparameters changing in storage degradation testing, the modeling storage reliability,storage reliability assessing method, and degradation parameters predictionmethods of aerospace EMR are extensively investigated. These studies will providethe support and reference for determining and extending the life of missile weaponsystem.First of all, in this dissertation: firstly, the test and analysis system for storagedegradation test is designed which uses FPGA and ARM SCM architecture assystem’s hardware core. Signal acquisition and analysis system of high speedmult i-channel is built by distributing control method. This test system provides thepossibility of measure synchronously up to40relays’ contact resistances ècontactvoltage drop and coil current. Software algorithms of relay time parameters aredesigned and implemented. The upper computer software is developed to carry outfunctions that test parameters setting, trends showing and data querying ofdegradation parameters by VC++object orient programming. The time parametersdetective resolution can achieve1s and the measurement resolution of contactresistance is no more than0.01m.This test and analysis system provides theresource of degradation data and effective testing platform for studying storage reliabilit y.Secondly, the traditional reliability testing methods based on field storagecan’t satisfy the needs in storage reliability evaluation of long-life products. Thisdissertation did the exploratory research on the storage degradation test method andtest process for aerospace EMR. The experimental data of contact resistance andtime parameter are analyzed by the methods of mathematical statistics and diagramanalysis. And the variat ion law of performance parameters changing with time isobtained, which provides the bases for determining degradation sensit iveparameters.Thirdly, based on the structure and function of aerospace EMR, the storagefailure mechanism is investigated by conductive properties themselves. Themicroscopic morphology and changes in chemical elements for relay contactsurface was analyzed by SEM and EDX regularly, which provide references for therelay storage failure mechanism of relay. The relay closing time storagedegradation model is established based on stress relaxation, and applied theLarson-Miller empiric formula. According to the diffusion theory, storage equivalentkinetic model of relay is built by three-dimensional Fick equation. This modelconnects resistance increasing of aerospace EMR with temperature, contact voltagedrop, contact stress and some other factors effectively. And, these studies providethe new ideas and references for rapid assessment of relay contact resistance.Finally, the exist ing storage reliabilit y assessment methods are mostly staticand post-mortem. They acquiesce in a fact that product distribution subject to aspecified distribution and estimate the product reliabilit y based on empiricalformula. Based on Holm electrical contact theory and contact storage failuremechanism, the storage reliabilit y assessment model of aerospace EMR isestablished which synthesizes the stochastic and deterministic of contact resistanceincrement. Meanwhile, the parameters estimation method of assessment model isstudied, and storage reliabilit y of aerospace EMR is assessed. Artificial neuralnetwork has strong nonlinear adaptive capacity and Grey system theory weakensdata sequence fluctuation. The G-ANN combination prediction model of relaydegradation parameters has been built up by combining above characteristics. Thisapproach forecasts the contact resistance degradation of aerospace relays in thestorage test, and the results show that this method has higher precision ofprediction. Prediction parameters preprocessing method is proposed whichcombines time series analysis with one-dimensional wavelet transform method. This reduces the random signal’s influence on the prediction precision in predictionparameters. Parameters of the storage degradation model are estimated throughregression theory. And the storage life of Aerospace EMR under normal stress ispredicted.The research results in this dissertation provide the necessary theoreticalmethod and basis for studying storage reliability of the aerospace EMR. Its keytechniques and methods could be also applied to other electromechanicalcomponents storage reliability studies.