Xiaodan Sun

Bio: Xiaodan Sun is an academic researcher from Harbin Engineering University. The author has contributed to research in topics: Lamb waves & Welding. The author has an hindex of 2, co-authored 3 publications receiving 9 citations.

Research on Pipeline Damage Imaging Technology Based on Ultrasonic Guided Waves

Abstract: Pipeline structures are important structural components that cannot be replaced in actual engineering applications. Damage to a pipeline structure will create substantial safety hazards and economic losses in a project. Therefore, it is extremely important to study damaged pipeline structures. In this paper, L(0,2) mode guided waves are used to identify, locate, and image single and double defects in straight pipe structures. For the case where there is a single defect in the straight pipe section, the influence of different excitation frequencies on the reflection coefficient of L(0,2) modal guided wave is studied, and the optimal excitation frequency of L(0,2) guided wave is 70 kHz when single damage is determined. For the case of double defects in the straight pipe section, the double-defect size, the distance between the defects, and the relative defect positions are studied, and the influence of the defect recognition effect is analyzed. The propagation path of the ultrasonic guided wave in the double-defect pipe section is analyzed. Finally, the effectiveness of the three-point axial positioning method and damage imaging method is verified by the single-defect tube segment ultrasonic guided wave flaw detection experiment.

Damage identification in welded structures using symmetric excitation of Lamb waves

Abstract: Damage monitoring systems based on Lamb wave health monitoring technology have attracted considerable attention for scientific research and industrial applications In this article, two types of si

Double Crack Damage Identification of Welded Steel Structure Based on LAMB WAVES of S0 Mode.

Abstract: Steel structures are widely used in large-span bridges, offshore platforms, mining equipment and other large-scale buildings. The damage of steel structures will cause significant safety risks in a project. Therefore, it is of great significance to identify and study damage to steel structures. In this study, the propagation of Lamb waves in a steel plate with double cracks is simulated. Using finite element analysis and experimental study, damage identification and damage imaging of double crack damage to a steel plate are performed, and the numerical simulation results are in good agreement with the experimental results. Considering the reflection and transmission of Lamb waves at the welding seam, the location and imaging of crack damage in a welded steel plate are also studied. The imaging results obtained from simulation and experiment show high level in accuracy. By comparing the amplitude of the signal in the propagation process, it is concluded that the transmission energy at the weld seam decreases.

Study on Aerodynamic Noise Numerical Simulation and Characteristics of Safety Valve Based on Dipole and Quadrupole

Abstract: Aiming at the problem that it is difficult to accurately predict the aerodynamic noise in the safety valve exhaust process, a new numerical simulation method that comprehensively considers the dipole sources and the quadrupole sources is proposed The RNG k–e model is used to simulate the steady-state flow fields, LES numerical method is used to simulate the transient flow, and then the unsteady disturbances are used as source terms in the generalized FW–H solver incorporating the dipole and quadrupole terms to solve for the acoustic field This simulation method is used to calculate the exhaust noise of the safety valve under six different operating conditions, the sound source characteristics of the exhaust noise of the safety valve are analyzed, and the safety valve exhaust test of different working conditions was carried out The results show that the relative errors of total sound pressure level between simulation and test does not exceed 5% under different exhaust pressures and different opening heights of the safety valve flap By comparing the total sound pressure level logarithmically superimposed with the total sound pressure level of the dipole and the quadrupole, the sound source characteristics of the aerodynamic noise of the safety valve are mainly dominated by the sound source of the quadrupole As the opening height of the safety valve flap and exhaust pressure increase, the total sound pressure level of the safety valve exhaust noise increases, while the relative errors between the simulation results and test data decrease The proposed simulation method can be accurately applied to the prediction of the safety valve exhaust noise, and the prediction accuracy of this simulation method also increases when the opening height of the safety valve flap and exhaust pressure increase

Research on Pipeline Damage Imaging Technology Based on Ultrasonic Guided Waves

Abstract: Pipeline structures are important structural components that cannot be replaced in actual engineering applications. Damage to a pipeline structure will create substantial safety hazards and economic losses in a project. Therefore, it is extremely important to study damaged pipeline structures. In this paper, L(0,2) mode guided waves are used to identify, locate, and image single and double defects in straight pipe structures. For the case where there is a single defect in the straight pipe section, the influence of different excitation frequencies on the reflection coefficient of L(0,2) modal guided wave is studied, and the optimal excitation frequency of L(0,2) guided wave is 70 kHz when single damage is determined. For the case of double defects in the straight pipe section, the double-defect size, the distance between the defects, and the relative defect positions are studied, and the influence of the defect recognition effect is analyzed. The propagation path of the ultrasonic guided wave in the double-defect pipe section is analyzed. Finally, the effectiveness of the three-point axial positioning method and damage imaging method is verified by the single-defect tube segment ultrasonic guided wave flaw detection experiment.

Design of Electromagnetic Acoustic Transducer for Helical Lamb Wave With Concentrated Beam

Abstract: Guided wave is advantageous to inspect pipe-like structures because of its long-distance propagation. Due to the curved structure of pipeline, guided wave can spread spirally with a helix angle. However, the current transducers focus more on the narrow or omni-directional beam than the helical form. This work presents the designed transducer to generate helical Lamb wave with concentrated beam. The transducer is developed using permanent magnets and arc-coil based on the principle of electromagnetic-acoustic conversion. The numerical analysis applying finite element method is conducted to verify the theoretical model of the transducer. The angular profiles are obtained to study the propagation of helical Lamb wave. Further, experiments are designed to demonstrate the performance of proposed transducer. The results from the experiments show good agreement with the numerical simulations. Besides, the parameter of central width is investigated and the half-angle of divergence is calculated. The results are compared with that from traditional transducers. The comparison indicates the superiority of the proposed transducer in generating helical Lamb wave. Therefore, the designed transducer could be a potential alternation for pipeline inspection based on guided wave.

Characteristic analysis of electromagnetic acoustic transducers for helical shear horizontal wave based on magnetostrictive effect.

Abstract: The electromagnetic ultrasound detection technology provides an efficient method to inspect the structural health status. For the pipeline structure, the guided ultrasonic wave propagating along the axial direction has been the focus of the current research. However, the helical wave owns the advantage of obtaining the defect information in extra angles and has not been explored sufficiently. In this work, a transducer with a sector configuration is designed for generating helical shear horizontal waves in a pipeline. The magnetostrictive effect is analyzed, and the model is built in the finite element simulation software of COMSOL Multiphysics. The electromagnetic field and displacement distribution are studied. To evaluate the performance of the transducer, the half divergence angle is defined to measure the acoustic beam and evaluate the capacity in generating helical waves. Corresponding experiments are also implemented to analyze the influencing factors in the structural design of the transducer. The results indicate that the pulse cycle affects the half divergence angle slightly. The compromise should be considered when designing the central angle of the transducer because it influences the signal amplitude and further imaging resolution in a contradictory way.