Accelerometer Selection for Vibration Testing - Vibration Test 101

[Music] when you boil it down to its essentials vibration testing is about introducing a specified level of energy into a test article Act or over a range of frequencies we normally measure and control this energy with one or more accelerometers understanding the capabilities of these accelerometers is important to ensure that vibration energy is accurately measured and controlled some of the more significant accelerometer characteristics that need to be considered when selecting an accelerometer for a vibration test are measuring range sensitivity frequency response mass mounting method and operating temperature accelerometers are designed to measure a specific range of accelerations because of this two things should be considered when selecting the appropriate one an accelerometer can be permanently damaged if the test level exceeds the maximum measuring range this can be prevented by using an accelerometer with a larger measuring range however using two larger measuring range can make it difficult for the vibration controller to see the accelerometer signal above the background electrical noise an accelerometer sensitivity is the ratio of its output in millivolts or Pico coulombs to its input in G's if you're performing a test at a low level for instance like 0.25 G's rms it's necessary to select an accelerometer that has a high sensitivity otherwise the controller will not receive a signal higher than the background electrical noise and will be unable to control the shaker accelerometers are designed to measure acceleration accurately over a range of frequencies some are optimized for lower frequencies even down to DC levels others are good at measuring very high frequencies but can't accurately measure below 2 Hertz because of this it's necessary to match the frequency response of the accelerometer to the frequency range of your test profile the manufacturers specification for the accelerometer will define the acceptable frequency range for the accelerometer accelerometers aren't only used for controlling a shaker you can also use them to measure the vibration response of an object by attaching an accelerometer to the object if the object mass is low in relation to the mass of the accelerometer the combined mass can affect the vibration response which is measured for this reason very lightweight accelerometers somers light as point 6 grams are sometimes used to monitor objects like PC boards or small electronic components accelerometers need to be attached to the surface where we want to measure acceleration for this purpose we use three types of attachment methods depending on the test condition threaded mounting studs offer the best performance and are least likely to come loose during a vibration test high strength adhesives can achieve similar performance as a threaded stud and are the preferred attachment methods for very small accelerometers which do not have a stud mounting for quick tests where the accelerometer needs to be moved around frequently or for short duration tests wax can also be used as an attachment method however this method can and the higher frequency response of the accelerometer the temperature which an accelerometer is exposed to will affect its sensitivity and can significantly change the acceleration values that you're measuring again the manufacturers specification for the accelerometer should be consulted to ensure that the accelerometer will measure accurately at the temperature under which you're testing your vibration testing laboratory will carefully choose the accelerometers used for your vibration test based upon the condition which you need to measure and control [Music]

Channel: Paragon Systems Testing

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Id: T7NWmSkbR10

Length: 4min 23sec (263 seconds)

Published: Tue Jul 14 2020