Lamb Wave Transducer Array For Inspection Of Plate Using A Virtual Focused Method

Storage tank is major equipment in oil and chemical industry, and is also infrastructure for national strategy oil reservation. Due to long-term storage of inflammable, explosive, poisonous and corrosive medium, storage tank is special equipment with high risk. Storage tank is prone to have accident, and is harm to safety of life and property. It is necessary to develop nondestructive testing technique to guarantee the safety operation of storage tank, which has great value for industrial application and scientific research. In this paper a virtual focused technique with Lamb wave transducer array is developed to inspect plate structure. The main research work includes:1. A virtual focused technique is developed using Lamb transducer array. Without the phased hardware system, the data received by transducer array are processed with the phase shift and amplitude weighted optimization, the acoustic beam is focused in any direction for defect detection.2. Using the numerical simulation data, the research on influences of the width of main lobe and the level of side lobe by the diameter of the transducer array, the number of array elements and beam directions are conducted. The condition under which there is no obvious side lode is obtained; it can provide guidance for parameter setting of the following experiment.3. Based on the developed the automatic switch and the omin-directional single lamb mode transducer, an automatic experimental system for lamb wave transducer arrays nondestructive testing in plate is established. The experiments have been conducted using the developed Lamb waves transducer array system. The experimental data have been processed with phase shift and amplitude weighted optimization. It is showed that the virtual focused technique with transducer array can recognize the features (such as edge and defect) in plate.