Study On Propagation Of Stress Wave In Welded Seam

Welding has been widely used in the modern project. With the rapid economicdevelopment in China, variety of large-scale steel projects are in the construction oroperational phase. However, the number of injuries occurred in the steel is growingdue to corrosion of the steel itself and the uneven of the performance, as well as thedefects generated during welding. If the defect cannot be found, serious security riskwould exist. At present using conventional methods for detection is not only costly,and also inefficient. This paper introduces the elastic stress wave propagation in thesteel, especially in the dissemination of scattering encountered in the case of weld.Base on this, further research on waveform changes in structural cracks or holes isdesired. This study aims to develop a new type of in-service inspection method to beused to the primary position of cracks and other defects in large weld steel. It canprovide the basis for judging the quality of life components.In this paper, wave equation is used to establishthe forward modelof propagationof hammer stress wave in the steel structure to obtain the placement, stress and strain.First stress wave propagation form is modeled in the uniform steel structure, and thenthe form in layered medium is established to simulate the scattering in the base metaland weld. Base onthis, changes of stress wave propagation in the circular and narrowshaped defects in the weld are simulated. Finally, virtual instrument Labview, DAQ2000series capturing cards, resistance strain gauge and accelerometer are used toacquire corresponding hammer experimental data. Scientific software is used for dataprocessing, to verify the relevance of the theory and simulation.Experiments show that forward model base on the forward model essentiallyreflect the propagation form in the weld steel structure and defects. Data acquiredfrom different locations is in line with the simulation. But the selected point sourceand the size of steel shows great impact to the results. The research of stress wavetechnology for the steel structure in-service inspection is still in its infancy, thealgorithms and models are not complete, and hence need further research.