An improved instantaneous baseline method for pipe structures based on distance compensation using guided waves

Among the baseline-free damage detection techniques based on guided waves (GWs), instantaneous baseline measurement is easily applied in practical situations. However, the number of transducers increases when large structures are inspected, and the operation becomes quite complicated because the excitation signal has to be applied to the actuators one by one. In this paper, an improved instantaneous baseline technique based on distance compensation is proposed. This technique has two advantages: (1) a smaller number of transducers is required; and (2) the operation of the excitation and receiving of GW signals is very simple. A distance compensation algorithm is developed to predict the signals in intact pipe. The efficiency of the wave prediction in intact pipe is validated through simulation. A baseline-free damage detection method for the pipe structure is proposed in this paper. The feasibility of the presented method is demonstrated by the simulation of two damage cases. Moreover, experiments are performed to verify the wave propagation and the feasibility of the proposed method.