An Experimental Comparison of Modal-Based SHM Techniques Using Strain or Acceleration Measurements

Abstract

This work presents experimental results for structural health monitoring methods based on modal properties. Two test subjects are considered for the study - a simple composite beam in T-shape and a more complex and realistic system, a composite helicopter main rotor blade (MRB). Different sorts of sensors are used for the purpose of identifying damage, such as piezo strain sensors and accelerometers for the composite T-beam and just accelerometers for the helicopter MRB. Damage is simulated on the test objects by attaching a small mass to different locations. The damage detection methods studied are the coordinate MAC (COMAC), enhanced COMAC (eCOMAC) and scaled COMAC (sCOMAC). The modal properties from the composite T-beam and from the helicopter MRB are obtained using a least squares fit (PolyMAX) and the various techniques mentioned above are implemented and compared.