A parametric study for a structural intensity based damage detection technique

A preliminary investigation to test the feasibility of a Structural Intensity (SI) based damage detection technique is presented in this paper. A parametric study was performed in order to evaluate the effects of the main structural and experimental parameters on the distribution of energy flow in a test structure. It was determined that the magnitude and the gradient of the SI field were significantly affected by the characteristic damping levels found in the test structure. In order to identify feasible ranges of interest for the different functional parameters with respect to the types of airframe applications of interest, vibration and damping measurements on a UH-60 transmission frame were obtained and the results used to guide the numerical simulations. The Total Transmitted Power is one of the main parameters used for the health assessment of the test structure. This parameter, however, is strongly affected by the damping levels which reduce the amount of power that effectively reaches an energy sink. Preliminary measurements made on a plate structure with progressively increasing damage are presented illustrating the use of SI for damage characterization. A new concept based on an Active Energy Sink is introduced in order to counterbalance the effects of the different practical structure inherent dissipative mechanisms and to maximize the Total Transmitted Power independently of the characteristics of the structure being assessed. Finally, a Nonlinear Structural Intensity technique is also suggested as a possible approach to extend the capabilities of the SI based SHM system as well as to potentially perform damage localization.