Dynamic Photoelastic Based On Phased Array Detector Development Of Imaging System

Ultrasonic testing is a widely used testing method in the field of nondestructive testing.With the increasingly strict quality requirements of the country and the rapid development of modern non-destructive testing technology and the increase of more complicated components,researchers have used the principle of radar to study ultrasonic phased array testing and play an irreplaceable role in many fields.In order to make the phased array detection reliable,the performance of the phased array ultrasonic detector needs to be tested.At present,it is tested by the imaging system of the phased array detector itself,but the imaging method of the phased array detector is not a real acoustic wave.In order to visually see the ultrasonic waves and realize the ultrasonic imaging in the phased array detector,a phased array ultrasonic detector imaging system based on the dynamic photoelastic method was designed.This system uses the dynamic photoelastic method to directly observe the ultrasonic waves of the phased array ultrasonic detector on the optical glass test block.It can not only judge the performance of the instrument,but also study the propagation characteristics of the ultrasonic wave excited by the phased array detector.This article elaborated the development of the entire photoelastic system from two aspects of hardware and software.The main contents of the research are:First of all,the design and production of the dynamic photoelastic system light source used for ultrasonic phased array,using laser as the light source,using FPGA to design an acousto-optic delay trigger laser controller,control laser and phased array ultrasonic detector.The FPGA integrates the MC8051 IP core and soft core storage unit,counting delay module,pulse width adjustment circuit(trigger laser)and other system improvement circuits.It is also programmed in the MC8051 IP core through assembly language to complete the frequency division module,system self-trigger module,external trigger module,self-external trigger switch and serial communication setting module.The power supply circuit and the peripheral expansion circuit are designed to realize the high-precision delay trigger of the laser and phased array detector.Through CIVA ultrasonic simulation software,the parameters of the phased array ultrasonic transducer are optimized.Parameters such as the array element spacing,array element size,number of simultaneously excited array elements,and excitation signal frequency of the phased array transducer were determined.The simulation results show that: 1)the greater the number of elements,the stronger the energy of the ultrasonic transducer at the focal point;2)the larger the element size,the stronger the energy generated by the transducer;3)the lower the frequency,the more the energy of the transducer Strong;4)The array element spacing should be less than the ultrasonic wavelength,so no grating lobe will be generated.Finally,an ultrasonic phased array imaging experiment based on the photoelastic method was designed to realize dynamic real-time observation of the imaging quality of the ultrasonic phased array,and through the measurement function of the software,the focus point position and focus focus size were accurately measured.It is of positive significance to evaluate the imaging quality of phased array.