Vibration Testing—What Is Vibration Testing?
Vibration testing uses an electrodynamic shaker to induce forced vibration of a system. By using multiple accelerometers on the shaker head and mounted part, the input (base) and output (test unit) frequencies can be measured and recorded. Both the input and output frequencies are measured to ensure that the test unit is experiencing the intended testing parameters. In addition, by measuring the input and output frequencies characteristics such as transmissibility, natural frequency, and resonance frequency can be determined. Other properties such as damping ratio can be calculated with further vibration analysis.
The main goal of vibration testing is to see if a component or system can withstand a given set of conditions; these conditions are determined by the end customer and test method. For example, a customer wants an exterior sensor to be designed to MIL-STD-810G or Military Standard 810G. Since the sensor will be mounted on the vehicle as secured cargo we select Procedure 1 and Category 4 in method 514.6, located on page 264 and 267 respectively. The selected test corresponds to a frequency sweep from 5 Hz to 500 Hz in the vertical, transverse, and longitudinal directions, so the part in the test fixture or the shaker base plate will need to be rotated. During and after the completion of the test, the test units are inspected for any signs of structural damage. In addition, an operational test can be performed, where the electronic component is powered during the vibration test, and observed if the test unit loses its functionality during testing. Below is the graph and table for the random vibration requirements of the tests.