Design Of Virtual UT Instrument

Non-destructive testing (NDT) is a type of technology that detects and evaluates flaws in material without affecting its internal structure. By using NDT, immaculate products with poor quality or accidents caused by unqualified products could be avoided. Therefore, NDT technology is vital for business and profits. Currently, methods of Radiation Testing, Magnetic Particle Crack Testing, Penetration Testing, Eddy Current Testing and Ultrasonic Testing (UT) have been wildly used by the industries. Among them, UT is an essential branch that has the advantages of wide detecting field, thorough testing, high sensitivity, easy to operate, speed, correctness, economic and harmless to human bodies.Most of the domestic intelligent products of ultrasonic defect detection use microchip computers as the core units and Large Scale Integration (LSI) chips as their peripheral circuits. As they are bounded by the complex designs, high-costs, long development cycles and difficulties of implementing the software, their designs and operations are not much flexible.To overcome those disadvantages, a virtual ultrasonic defect detecting instrument based on the concept of Virtual Instrument (VI) is presented in this paper. The VI is consisting of a personal computer, the software packages it used and general hardware interfaces. By using the personal computer, the instrument turns to be a highly intelligent one.The design is divided into two. The first part is the general interface of the hardware, which drives, monitors the ultrasonic sensor, receives signals generated by the sensor, converts the analog signals into numerical formats and sends them to the computer through a communication line. The second part is concerned with designing and implementing the software to be used by the VI. There are two tasks, the layout of the user interface and the process / result display of the signals that represent the defect in the material.With the personal computer and its advantages of data analysis, data processing, data recording and interactive user interface, the implemented VI has features of simple circuit design, low-cost, powerful functions, friendly userinterface and intuitive result displaying. The VI also accomplished functions of massive signal processing and recording, which are difficult to implement for general intelligent units.In addition, the VI has the ability to calculate the K value and sensor distance automatically. Those features have not been archived in domestic products of the same type, the two parameters of which are manually determined and the testing results could be quite different from person to person. The design discussed in the paper solved the problem by removing the factor of the interferences from the operators.