Fault Diagnosis Of Crankahafts Components For Diesel Engine Based On Angularvibration

As a power machine,the diesel engine plays a great role in life and industrial production.The diesel engine crankshafts system is composed of many components.The coupling and torsional vibration damper are the key components that connenct the crankshafts system and transnit torque,which have an important infiuence on the safety and reliability of the power equipment.The failure of coupling and torsional vibration damper will have great influence on the reliability,stability and safety.Therefore,it is of vital significance to diagnose fault and evaluate the damaging degree.This paper analyses the torsional vibration characteristics of a 4100 diesel engine under steady and unsteady conditions.The influence of the failure of diesel engine crankshafts components on torsional vi bration modal parameters is studied and sensitivity analysis is conducted.The Kriging surrogate model between the structural parameters of the crankshafts components and the torsional vibration modal parameters of the crankshafts system is constructed.Fault diagnosis system for crankshafts components of diesel engine is developed.The simulation and experimental analysis of the torsional vibration characteristics of a 4100 diesel engine are studied under steady state and non-steady state conditions.The effect of different acceleration on the identification value of natural frequency of shafting system in non-steady state diesel engine is analyzed.For the first two-stage torsional vibration modes of the crankshafts system,the different accelation of the diesel engine have less influence on the first two modes of the crankshafts.In the steady state and non-steady state conditions of the diesel engine,the identified natural resonance frequency of the crankshafts is close.This paper establishs equivalent model of a 6240 diesel crankshafts,the influence of change in stiffness and damping because of single and multiple faults on the torsional vibration modal parameters is studied by simulation calcul ation method.The sensitivity analysis is performed to determine the torsional vibration modal characteristic parameters that are sensitive to different faults in the crankshafts components.A method of diagnosing fault components is presented based on Kriging surrogate model.The Kriging surrogate model between the structural parameters of the crankshafts components and the torsional vibration modal parameters of the crankshafts system is constructed.Samples are selected by means of uniform sampling.Kriging surrogate model is determined by a combin ation of first polynomial and Gaussian function.The kriging surrogate model is used to diagnose the fault of the 6240 diesel engine.The fault diagnosis of the coupling ? tossional vibration damper ? coupling and tossional vibration damper are diagnosed.The diagnosis error is within 5%.The model has a high degree of fitness,and can diagnose faulty components quickly and accurately.Based on the above research es,fault diagnosis system for crankshafts components of diesel engine is developed.The software mainly consists of 4 modules : crankshafts system basic parameter input ? torsional vibration analysis ?modal anaiysis of torsional vibration and fault diagnosis of crankshafts components.The software platform is designed for fault diagnosis of diesel engine crankshafts components,and the software has strong pertinence and compatibility,and easy to use;the calculation speed of the program is fast,and it occupies less computer resources.The research work in this paper not only enriches the fault diagnosis research methods of diesel engine crankshafts components,but also achieves the fault diagnosis and damage assessment.