Research On Solid Defect Detection Method Based On Broadband Ultrasound

Since entering the 21 st century,The development of modern manufacturing industry in the direction of the high accuracy,More and more requirements are put forward for the detection of solid parts.Ultrasonic nondestructive testing with high sensitivity,strong penetrating power,good directivity and fast inspection speed,low cost,the equipment is relatively simple,harmless to the human body,etc,The use of ultrasonic wave propagation and attenuation characteristics in the medium to test whether the tested object has defects,Ultrasonic testing become the most widely used means of nondestructive testing.Based on the solid surface defect detection as the research background,When defects or cracks are located on the surface or near the surface,In near-zone sound pressure has a lot of ups and downs of the near-field effect,And in the longitudinal wave in the transmission of pulse reflection blind spots.And the effect of defect orientation on the detection sensitivity,This paper presents a method for detecting solid defects by multidirectional controllable coupling parts,And developed a wireless ultrasonic measurement system to realize the method,And verify the exact feasibility of the method.The innovation and main research work of this paper is as follows:1.This paper presents a method for detecting solid defects by multidirectional controllable coupling parts,Multi direction coupling control is arranged between the tested firmware and the ultrasonic transmitting and receiving probe array,Conversion of solid surface or near surface defects into solid internal inspection,Which overcomes the near-field effect and blindzone problem existing in the detection of solid surface defects.2.The use of distributed ultrasonic probe transceiver array combined with multidirectional controllable coupling for each detection to improve the spatial resolution of defect detection,Using a chirp signal as an ultrasonic signal source,The data collected by the wavelet transform is used for noise reduction,And the mutual correlation method and the fractional Fourier transform are chosen to carry out the time delay estimation of ultrasonic echo signal.3.Developed a wireless ultrasonic measurement system,And complete the basic function of the system test,Select the test firmware under limited laboratory conditions,The solid internal defects and surface defects were examined in different scenarios,The feasibility of the method in the solid defect detection is verified,And get good results.