Acoustic Source Localization in Composite Plates Using Non-Linear Ultrasonic Technique - SPC-I

A new acoustic source localization (ASL) method that uses the Non-Linear Ultrasonic (NLU) Sideband Peak Count-Index (SPC-I) technique is presented. This method takes advantage of the robustness of the SPC-I technique to predict the location of an acoustic source in an orthotropic composite plate. The proposed method does not require the signal attenuation or time-of-arrival information at the sensors, that other ASL methods need. Since the signal attenuation information is unreliable because different sensors can have different sensitivities due to variations in attachment conditions, a desirable technique should avoid any dependence on the attenuation information. Additionally, no knowledge of the composite plate material mechanical properties is required in this proposed method. This new approach is performed by placing a number of sensors on the composite plate and recording the signals that are generated by the acoustic source. The recorded signals are then processed to obtain the SPC-I value for each sensor. The SPC-I values for each sensor are then used to run through an algorithm that attempts to predict the location of the acoustic source. The composite plate is considered a non-linear material. Therefore, when the signal propagates a longer distance through the plate the recorded signal should show a higher SPC-I value. This phenomenon occurs mainly due to signal scattering and frequency modulation due to material nonlinearity. This phenomenon of increasing SPC-I with propagation distance can be taken advantage of to predict the location of an acoustic source by solely using the non-linear SPC-I parameter. A Carbon Fiber Reinforced (CFR) composite plate with the dimensions of (500x500x1mm) is used for the acoustic source localization in this manner. Experimental results show that by using this approach, the acoustic source can be predicted at various locations using different excitation signals with reasonable accuracy.