A TECHNIQUE FOR MODAL DATA ACQUISITION IN REMOTE LOCATIONS USING HAND PORTABLE INSTRUMENTATION

摘要

A method for collecting analog modal test data using hand portable, battery powered equipment has repeatedly proven to be very successful during the past two years at the various Department of Energy projects and facilities. Modal data is collected through the utilization of an impulse hammer and accelerometers (with battery powered charge or voltage amplifiers) directly onto a lightweight, battery powered instrumentation tape recorder. A small storage oscilloscope is used to ensure that the data being collected is within the dynamic range of the recorder. The recorded test data is then taken to a laboratory and entered into a modal analyzer. Amplitude differences of less than five percent were demonstrated in laboratory comparisons with standard data collection methods. All instrumentation is calibrated using NBS traceable standards. A total weight of the equipment is less than forty pounds which allows the collection of modal data at remote locations. Examples are given to show typical test setups and data taking practices that mitigate problems with dynamic range, distortion and extraneous noise.