The Search for Optimal Sensor Network in Lamb Wave-based SHM Method

Abstract

In this paper the investigation of a structural health monitoring method for thinwalled parts of structures is presented. The concept is based on the guided elastic wave propagation phenomena. This type of waves can be used in order to obtain information about structure condition and possibly damaged areas. Measurement of the wave field was realized using laser scanning vibrometer that registered the velocity responses at points belonging to a defined mesh. Determination of the optimal placement of sensors is a very challenging mission. In conducted investigation laser vibrometer was used to facilitate the task. The chosen mesh of measuring points was the basis for the investigation. The purpose was to consider arrays of piezoelectric sensors and find the optimal solution. Instead of using vast amount of piezoelectric sensors the earlier mentioned laser vibrometer was used to gather the necessary data from wave propagation. Sensors networks geometries were picked out from the measured points. Next, the signals gather by this non-contact method for the considered network were input to the damage detection algorithm. The results of damage detection for the selected networks were compared. The signal processing was conducted in MATLAB with the procedures developed by authors. Damage detection algorithm was based on a procedure that seeks in the signals the damage-reflected waves. Knowing the wave velocity in considered material the damage position can be estimated.