| The turbine disk is a key component of the aero-engine.It runs in the harsh and complex environment of high stress,high speed and high load.Even if there are minor defects and fatigue damage,it may lead to catastrophic consequences.Therefore,non-destructive testing of turbine disks is extremely important.Theory and experiments shows that the crack in the component can still work under the same load until the next maintenance before expanding to the critical dimension of the fracture.Residual life evaluation plays an important role in the safe operation of the component.The evaluation method of residual life not only needs to detect defects,but also needs to quantify the size changes of defects accurately at each stage,which puts forward higher requirements for non-destructive testing methods.The single-crystal probe used in the conventional ultrasonic testing has a small detection range,low sound beam energy,and insufficient detection accuracy for small defects in the aviation turbine disk.Phased array ultrasonic testing technology can form a focused,deflected,high energy detection beam in the workpiece and provide a variety of display modes.In recent years,it has been widely used in non-destructive testing of aero-engine turbine disk.However,the complex structure,geometry and material properties of Aeronautical turbine disk lead to the problems in the ultrasonic phased array detection technology.Therefore,it is the main content of phased array quantitative detection in improve the sound field control mode and detection ability of ultrasonic phased array,and explore a new quantitative method and improve the quantitative accuracy of ultrasonic phased array,The concrete is carried out 3 aspects of research:Firstly,the parameters of ultrasonic phased array are optimized.The influence of probe frequency,array number,coupling mode and types of couplant on the image quality of phased array detection of turbine disk are compared and analyzed by the experimental method.The optimal setting rule of the turbine-disks' ultrasonic phased array testing parameters is given,and the ultrasonic phased array sector scanning detection and C scanning imaging detection test of the turbine disk are guided.Secondly,the research of self-defined focusing sound field control method is carried out.Three self-defined focusing modes for ultrasonic phased array detection are designed,the distribution characteristics and influencing factors of focused sound field are analyzed by establishing finite element model.The self-defined focusing scheme is applied to the test of aeronautical titanium alloy samples,and the detection effects of conventional focusing mode and self-defined focusing mode are compared and analyzed.Thirdly,the high-precision quantitative method for face type defects detection by ultrasonic phased array is presented.On the basis of obtaining clear diffraction wave images of surface defects,the method for measuring the orientation and size of face type defects based on diffraction wave images is proposed,and the results obtained by conventional pulse method are compared.In summary,study on the optimal configuration of ultrasonic phased array detection parameters,the quantitative method of surface defects,and the control method of focused acoustic field of phased array will improve the detection ability,imaging quality and quantitative accuracy of ultrasonic phased array.The research results are instructive to the industrial detection of ultrasonic phased array. |
PDF Full Text Request