Application Of Order Ratio Analysis In Fault Diagnosis Of Rotating Machinery

Rotating machinery is widely used in all walks of life in social production,which greatly improves production efficiency and promotes the flourishing development of industrial modernization.Therefore,it is of great significance to ensure the safe operation of the rotating machinery and the timely and accurate diagnosis of its faults.The rotational speed of rotating machinery in operation is strictly fluctuating,especially in the process of acceleration and deceleration.At this time,the vibration signals belong to non-stationary signals,which are not suitable for conventional Fourier spectrum analysis.Order analysis is a commonly used vibration signal analysis method of rotating machinery under variable speed condition.And the key is to transform the non-stationary signal in time domain into the stationary signal in angle domain through equal angle resampling,and this process is called order tracking.In recent years,the order tracking which based on instantaneous frequency estimation has been widely used because it does not need a hardware speed measuring device.The method uses time-frequency analysis technology to extract instantaneous frequency curve of reference axis,and then calculates resampling time.But the extraction of instantaneous frequency curve is affected by inherent defects of time-frequency analysis methods.Therefore,we need to find a more effective instantaneous frequency curve estimation method and apply it to order analysis so as to make better diagnosis of rotating machinery faults.To solve the above problems,this paper presented a method of instantaneous frequency curve estimation based on EEMD-HHT combined with time-frequency rearrangement.The method combined the advantages of EEMD-HHT and time-frequency reassignment algorithm and accurated extraction of instantaneous frequency curve of the reference axis and was applied to order analysis.Its specific implementation steps was illustrated and the validity was verified through the analysis of real example.In this paper,the fault diagnosis means of rotating machinery and the method of vibration signal analysis were introduced at first.Secondly,the vibration mechanism and fault characteristics of three common faults of rotating machinery were analyzed.Thirdly,the order tracking technologies were deeply studied.The principles,advantages and disadvantages of various order tracking methods were discussed and especially described the implementation of order tracking based on instantaneous frequency estimation in detail.Fourthly,the order analysis method based on the combination of EEMD-HHT and time frequency rearrangement was presented,and the concrete execution steps were given.Finally,a rotating machinery fault diagnosis experimental platform was built and simulated three faults of rotor imbalance,rotor misalignment and static and dynamic friction.The fault diagnosis of rotating machinery was realized by using the order analysis method based on the combination of EEMD-HHT and time frequency rearrangement.