The most commonly used condition monitoring method used to diagnose fatigue for rotating machines is called a vibration analysis. Vibration measurements can be taken on machine bearing housings with accelerometers (see this link) to measure vibrations. The level of vibration can be compared with historical baseline values, and depending on certain values and established standards such as load changes, the vibration information is used to assess the changes in machinery health condition.
Interpretation of the vibration signal obtained from the accelerometer is a complex procedure that requires specialized training and experience. In this day and age, it can be simplified by the use of technology. The vibration analysis technology of 2015 can provide the vast majority of data analysis automatically and deliver useful information instead of raw, undistinguishable data. One commonly employed technique is to examine the individual frequencies present in the signal. These frequencies correspond to certain mechanical components (for example, the various pieces that make up a rolling-element bearing) or certain malfunctions (such as shaft unbalance or misalignment). By examining the vibration frequencies and their natural harmonic signatures, the Condition Monitoring specialist can often identify the type of problem, and sometimes the root cause as well.
The entire purpose of vibration analysis and using special analysis instruments is to detect machinery fatigue weeks or even months before failure. The intention of this is process is ultimately to give operators and maintenance staff ample time to schedule replacement before a failure. In most cases, machinery failure will cause a much longer down-time costing business in excess of the condition monitoring and spare parts and labour combined.
Handheld data collectors and analysers are now commonly used on critical or balance of plant machines. The vibration analyst can collect data samples from a number of machines, then download the data into a computer where the examination of the data for changes which would indicate malfunctions and impending failures takes place. For larger, more critical machines where safety implications, production interruptions (downtime), replacement parts, and other costs of failure can be expensive, a permanent monitoring system is typically installed rather than relying on intermittent handheld data collection.
GVS reliability products offers many good value on-line systems to apply to heavy process industries such as pulp, paper, mining, petrochemical and power generation. These are dedicated vibration and temperature monitoring systems designed to be connected into a DCS or Scada system and be monitored around the clock by operational staff.
If you would like to learn more about vibration monitoring, please get in touch with one of our friendly staff today.
Information largely gathered from Wikipedia