An Inertially Referenced Non-contact Sensor for Ground Vibration Tests

A sensor is introduced that enables new methods for modal testing. Noncontact inertiareferenced velocity (NIRV) sensors may be mounted to a flexible stand without concern for measurement contamination due to motion of the stand. Non-contact sensors that are stand mounted may be setup without the test article, saving large amounts of the test article’s time, particularly for high-value articles and repetitive sequences on similar layouts. In cases where Computer Aided Design models of the test article are available, dimensions of the stand and measurement degrees-of-freedom may be identified without taking measurements directly from the test article. Specifications of the sensor are presented along with results comparing its output to that of traditional accelerometer data and examining differences in reduction methods. Data is presented that demonstrates insensitivity to motion at the NIRV sensor mount. Ground Vibration Test (GVT) results are presented from an aircraft with both NIRV and accelerometer data to demonstrate the interchangeability.