Development And Vibration Characteristics Of Internal Combustion Engine Vibration Test System Based On LabVIEW

With the rapid development of transportation&logistics,industrial&agricultural production and national defense equipment.etc,modern equipment with internal combustion engine has been widely used and dominated the market of thermal power plant.Lightweight,high-speed,and high specific power are trends of the ICE,which makes vibration of ICEs more severe.Therefore,it has been of great practical significance to control the noise and vibration of ICEs.Based on the vibration features of the ICE,identification of vibration system and analysis of vibration response are the core content of vibration and noise control of ICEs.So we need to develop a vibration testing system aiming at ICEs.Based on engineering requirement of the experimental research on vibration and noise reduction of ICE,today's technical characteristics of mainstream vibration testing and analysis platform were investigated.Then virtual instrument,computer technology and digital signal processing technology.etc.were used and finally,modular vibration testing and analysis system of ICE based on American National Instruments Corp was developed.Based on vibration characteristics of components of the ICE,algorithms like signal pretreatment,frequency domain analysis,time-frequency analysis and experimental modal analysis were studied and learned.The overall structure,module design and realization scheme of the modules of ICE vibration testing and analysis system hardware and software platform based on American NI PXI and LabVIEW were developed.Modal parameter identification of engine block and crankshaft in YN 38CRD2 diesel engine was carried out using PXI measuring control hardware of NI and ModalVIEW experiment modal analysis software.Modal characteristics of FEA and test methods(RFOP?LSCE?LSCF)were compared and analyzed.The rationality of modal parameters was evaluated by modal assurance criteria.Results show that:1)Modal shapes of the same order are almost the same and error of modal frequencies is less than 5%.Correlation coefficients of modality amplitude of the same order are all over 0.82.2)Maximum deformation of the block by vibration is mainly at crankcase.Elliptical vibration of cylinder bore could lead to gas and oil leakage in cylinder.3)Maximum deformation of crankshaft by vibration appears near both ends of the crankshaft and vibrating forms includes torsional,longitudinal and lateral vibrations.ICE vibration testing and analysis system was validated by tests using YN 38 CRD 2 diesel engine at 50%load condition based on test-bed in our lab.Measured signals of vibration were time-frequency domain analyzed through several signal analysis algorithms.Results show that:1)Vibration severities of the estimated points go up with the increase of the speed.2)Energy contained in vibration acceleration signal mainly focus on low frequency band of the signal.3)Low order modal characteristics of block and crankshaft were reflected in vibration signal of engine block and oil pan.Campbell diagrams of the components were analyzed,concluding that there are evident order features in vibration acceleration of components in which amplitudes of vibration acceleration of second,fourth and sixth order are the most prominent.Experimental results show that analysis results of the system could meet technical requirements specification of engineering application and prove to be practical and reliable.