如何有效的分析振动数据，大家是否遗漏了一些关键因素。
看到国外同行写的一篇文章，贴过来给大家看看。大家比较重视频谱分析，还有一些，例如信号本身质量，时间波形（原始的信号，频谱是傅里叶转变得来的，会丢失东西),相位，都应重视。:lol1. Ski-slope check: Quickly check forski-slope in case it was a bad measurement. Check the time waveform to see ifyou can determine what went wrong during the measurement.
2. Noise floor check:Noise can indicatethat impacting or rubbing is occurring.It can also be a sign of faileddata collection.Check the time waveform for the source of noise. If the noise floor is raised in a limited band, consider resonance.
3. Check twice line frequency: The peak at 120Hz or 100 Hz is related to electric motor faults (laminations, eccentricity,soft foot, etc.).The presence of a peak is not abnormal; if the amplitudeincreases it should be checked.
4. Order normalize: Find the shaft turningspeed peak (1X); this is the “first order”.If you are analyzing spectrafrom a machine with multiple shafts, identify each turning speed peaks.
a. If the amplitude of the 1X peak is highconsider unbalance (if in radial direction), unbalance in an overhung machine(axial direction), misalignment (axial direction), bent shaft/rotor bow(radial), pulley eccentricity (radial), flexibility or weak foundations(horizontal), and consider resonance (typically horizontal or vertical).
b. If you also see 2X, and/or 3X, and/or 4Xthen suspect misalignment (or cocked bearing).
c. If there are additional harmonics, considercoupling wear, and if the noise floor is raised, consider rotating looseness.
5. Relate peaks and patterns to orders: Youshould now identify which peaks are exact multiples of running speed (i.e.synchronous, e.g. 6X, 15X, 48X turning speed), which peaks are non-synchronous(i.e. non-integer multiples, e.g. 3.67X, 9.34X, etc.), which are sub-orders(i.e. fractional orders, e.g. 1/2 X, 1/3 X, etc.), and which are simplysub-synchronous (i.e. less that 1X, but not fractional, e.g. 0.48X, 0.76 X,etc.)
a. Synchronous:The vibration is likelyto be related to a rotating element: suspect flow problems (orders equal numberof pump vanes, fan blades, compressor vanes, etc.), and gear problems (peak atthe gear mesh frequency), motor problems (orders equal number of rotor bars,number of stator slots, etc.).
b. Sub-synchronous:Suspect belt faults(there should be harmonics), turbulence (a broad peak), cage faults (rollingelement bearings), oil whirl (journal bearing) or vibration from anothermachine.
c. Non-synchronous: Suspect rolling elementbearing damage (expect harmonics, check for 1X or FTF sidebands) or externalsource of vibration.Could also be due to combinations of otherfrequencies.
6. Harmonics and sidebands: Both are commonand both are clues to the type of fault.
a. Weak harmonics: Suspect “non-linear”vibration; that is, the vibration that is not smooth; something may berestricting the rotation.
b. Strong harmonics:Suspect thatimpacting is occurring (bearing damage, gear damage, etc.).
c. Sidebands: Any time you see sidebands, itmeans that vibration (internal forces) are rising and falling periodically, orthe speed is fluctuating periodically.There are many possible reasons.
7. Additional tips: Do not rely on linearspectra alone.There are hidden treasures to be found in spectra,waveforms, phase, and high frequency techniques.
a. Logarithmic display:Quickly toggleto logarithmic display, especially if the amplitude of any of the peaks arehigh - it will help you see sidebands and harmonics that have relatively lowamplitude.
b. Time waveform analysis: If you see a highnoise floor, harmonics or sidebands, you are advised to look at the timewaveform to better understand the nature of the fault.
c. Phase analysis:If you suspectunbalance, misalignment, flexibility, looseness or cocked-bearing, you areadvised to use phase for an accurate diagnosis.
d. Gears and bearings: If you suspect bearingor gear damage, study a time waveform (to study what happens as the balls rollaround the bearing and to study how the vibration changes as each gear toothcomes into mesh) and utilize enveloping/Shock Pulse/Peak Vue/Spike Energy, etc.
Of course, with more time, and animations and simulations, all of this is mucheasier to explain, and MUCH easier for you to understand; but I hope it hasbeen helpful.(Please note that there are other possible fault conditionsand analysis techniques; this tip is provided as a guide only.) 若能同时给出连接感觉更完整, 对大家是有帮助的, 谢谢
[ 本帖最后由 ChaChing 于 2010-1-28 20:55 编辑 ]
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有没有中文版的？ 没有中文版的，http://reliabilityweb.com/index.php/maintenance_tips/how_do_you_analyze_spectra_do_you_miss_key_information/ 有个链接方便多了，多谢
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