Research On Ultrasonic Phased Array Detection Technology Of Long-span Bridges Corrugated Steel Webs Weld Quality

As a core support member of the new long-span bridge,the corrugated steel web composite box girder structure replaces the traditional concrete box girder structure,and it has obvious advantages in strength,weight,span,applicability and transportation manufacturing.However,due to its unique structural design,it also encounters difficulties in quality inspection and evaluation.The welding method of the weld flat surface is opposite to each other,and the weld defects caused by welding are not in the traditional non-destructive testing field.Effective detection method.In order to solve this problem,this thesis proposes the use of ultrasonic phased array detection technology to study the T weld defects of corrugated steel webs.Ultrasonic phased array technology has been verified in the field of conventional T-weld with its advanced testing methods and concepts.It has a huge advantage in the detection of weld defects.This thesis first introduces the causes and types of weld defects in corrugated steel webs,as well as the commonly used detection methods and their advantages and disadvantages.The development history of corrugated steel web design and production at home and abroad,as well as the domestic and international status of the defect detection,the advantages of ultrasonic phased array in the T-weld field and the research status and progress at home and abroad are introduced in detail.Combined with the basic theory and sound field characteristics of ultrasonic phased array,the current main ultrasonic phased array probe array types and various parameters are introduced.Then,through simulation and simulation,the parameters of each component of the probe are transformed,and the influence of the changes of each parameter on the sound field characteristics of the ultrasonic phased array is analyzed.Then,using Wave2000/3000 finite element differential simulation software and laboratory testing equipment,the T-weld of the web is studied from the simulation and experiment,including:(1)Through the establishment of the T-shaped weld plane and surface simulation experiment model of the web board,the conventional ultrasonic detection simulation experiment is used to explore and provide reference for the ultrasonic phased array detection,and optimize the best conventional ultrasonic inspection wafer size 12 mm,detection The frequency is 2.5MHz and the wedge angle is 45 degrees.(2)Establishing the simulation experiment model of the plane and surface parameters of the T-weld of the ultrasonic phased array web,and combining the parameters obtained by the conventional ultrasonic to carry out the ultrasonic phased array detection simulation experiment,and the parameters of the flat surface are basically consistent and optimized.The best ultrasonic phased array detection array element number is 32,array element frequency 5MHz,wedge angle plane 45 degree surface 60 degree,array element width 0.2mm,focusing depth 12 mm,array element gap has no obvious influence on detection.(3)Combining the best parameters obtained by the simulation experiment,constructing the experimental testing platform for the conventional ultrasonic testing and phased array ultrasonic testing of the corrugated steel web specimens and various artificial defects,and analyzing the test results.Ultrasonic phased array detection technology is used to locate and quantify the artificial defects of corrugated steel web T-weld joints and the operability reliability is superior to conventional ultrasonic testing technology.Finally,combined with the problem of low coupling contact surface in the conventional ultrasonic phased array detection experiment of corrugated steel web,the improved design of phased array probe for this structure is proposed,which is based on the principle of acoustic lens combined with the actual T-weld of web.The simulation experiment of the surface self-focusing probe is taken as the exploration.On the basis of this,the simulation experiment of the soft-film ultrasonic phased array focusing probe is carried out,and the optimal parameters of the soft-film ultrasonic phased array focusing probe are obtained.The soft film ultrasonic phased array focusing probe is processed and fabricated,and the designed soft film probe is tested on the web T-weld test block.The soft film ultrasonic phased array probe is obtained.The detection result is basically consistent with the preset defect parameter,and the conversion equivalent difference of the flat curved surface is within the allowable range of the detection error.This indicates that the improved probe does not need to be refocused during the flat surface detection conversion process,and the detection result is consistent with the actual parameters,and the speed is faster and more practical and reliable.