Design And Development Of Ultrasonic Nondestructive Testing System For Additive Manufacturing Components

Metal additive manufacturing technology provides a new method with high feasibility,efficiency and practicability for the manufacture of metal parts with complex shapes,complicated processes and difficult to process by traditional manufacturing technologies.However,due to the microstructure characteristics and evolution law of materials under fast solidification conditions,mechanical properties such as elastic modulus,and different defect types,sizes,quantities,and distributions such as pores,inclusions,unfusion,and microcracks,etc.,and traditional casting and forging processes The comparison is very different,and the type,number,size and location of defects,the mechanical properties of the material,and the porosity greatly affect the quality,mechanical properties,and service safety of the component in actual use.In order to solve the problems of internal defect control,defect detection,and elastic mechanical property parameter detection of components that affect the development of metal additive manufacturing technology,this paper proposes the mechanical properties of various materials for metal additive manufacturing components based on the ultrasonic nondestructive testing theory.Ultrasonic non-destructive testing technology for precise measurement of parameters,porosity and internal defects.Through the development of high-precision ultrasonic scanning platform,basic theory of ultrasonic acoustics,and precision testing experiments,an ultrasonic non-destructive method for internal defects of metal additive manufacturing components was established to provide guarantee for the practical application and service performance of metal additive manufacturing components.The main research contents of this article are as follows:(1)Theoretical derivation of material mechanical properties parameters,porosity and damage defect detection.Firstly,the measurement formulas of ultrasonic P-wave velocity and surface-wave velocity in isotropic materials were derived,and the relationship between the mechanical properties of each material and the P-wave velocity and surface wave velocity of ultrasonic was obtained based on the Naiver equation in the sound field.Secondly,based on the theory of ultrasonic spectrum analysis,the empirical formulas of ultrasonic attenuation spectrum and acoustic attenuation coefficient and internal porosity of materials are used to solve the porosity in metal additive manufacturing components.Finally,the principles of ultrasonic spectrum analysis,signal analysis and processing,and ultrasonic non-destructive testing are combined.The ultrasonic echo signals obtained in the experiment are subjected to frequency domain transformation,waveform alignment,and window truncation,combined with peak imaging and frequency domain imaging.Imaging the test piece defect damage.(2)Based on the principle of ultrasonic non-destructive testing and the imaging method using ultrasonic echo,an ultrasonic non-destructive testing system was independently developed.Firstly,the hardware system of the ultrasonic non-destructive testing system was designed and built.The detection accuracy,through the hardware trigger function in the system,ensures the synchronization of movement and data acquisition,and meets the hardware system requirements for the material material velocity measurement of additive manufacturing components in the experiment.Then designed and developed dedicated control measurement and imaging software to achieve small step accurate scanning of each axis of the motion platform,real-time acquisition and display of ultrasonic echo signals,real-time frequency domain conversion of ultrasonic echo signals,and display of spectrograms.Waveform pre-processing and storage,timefrequency domain imaging at different depths in the test specimen.By writing signal processing algorithms in the program,waveform alignment is achieved,and the effect of system effects in A-scan waveforms is effectively removed.(3)The ultrasonic non-destructive testing system is used to scan and inspect the aluminum additive manufacturing components,and obtain the A-type scanning waveforms of each point on the test piece,the time-domain defect imaging map of the test piece,and the frequency-domain defect imaging map.After the experiment,the Ascan waveforms obtained from the points on the test piece were used to obtain the ultrasonic surface wave and longitudinal wave velocity.According to the relationship between the ultrasonic wave velocity and the mechanical properties of the component materials,the mechanical properties of the materials such as Poisson's ratio were solved.The backscatter signal was extracted from the A-scan signal at each point to obtain the ultrasonic attenuation spectrum of the specimen,and then the porosity of the material was obtained.Finally,the ultrasonic nondestructive testing system is used to scan and detect the A-scan signals obtained from the experiments of additive manufacturing components and the simulation results obtained in COMSOL are compared and analyzed.The results show that the two have a high degree of consistency,which verifies the ultrasonic nondestructive The accuracy of the detection system.