Experimental Research On The Dynamic Character Effect Of Welding Defects To The Steel Frame

Welding as a basic process methods, which are widely used in aerospace, ships, bridges, machinery, metallurgy, energy, petrochemical, construction and other industries. The welding process is often subject to the influence of various factors, sometimes the weld will inevitably generate residual stress, cracks, undercut, porosity, inclusions, incomplete fusion, incomplete penetration defects. Different types of welding defects have different geometric shape, contour, gray distribution, location, and the extension direction, and other features. Welded structure to keep development direction of the high parameter, large-scale, heavy, put forward more and more high demands on the welding quality. Welding defects will directly affect the mechanical properties of the components, which have an adverse effect in dynamic characteristics, fatigue strength and stability. The traditional theory of structural analysis of strength, stability, the theory has reached a very mature level. However, on the precise structure of the static and static load test alone does not guarantee the security and reliability of the structure, especially in the harmonic load, impact load,wind load, seismic load of response under dynamic loads, the more obvious and directly impact on people’s lives and safety. Comprehensive detection, assessment and health monitoring of civil engineering structure, we need to fully understand the dynamic characteristic parameter of the civil engineering structure. The modal parameters are the main parameters determining the structural dynamic characteristics. At present, the welding defects and dynamic characteristics of the relationship between the papers can be found less. Therefore, the study of steel frame welding defects to dynamic characteristics of the influence has certain practical significance. This paper is not saturated welded steel frame pilot study, analysis of welding defects on the dynamic characteristics of the steel frame of the law, preliminary estimates of its impact factor of the dynamic characteristics.This paper studies the main performance of the work in the following aspects:1. Describe the classification of weld defects, its causes and the impact on the structure. Summarize the different weld defects in welding steel structure. Discuss the case of welding unsaturated in this paper, the experiment through different welding rate on the dynamic characteristics of the steel beam. This paper puts forward through the different welding steel frame rate on the dynamic characteristics of the impact experiment, which discusses the unsaturated welding steel frame of the dynamic characteristics of the influence law.2. In multiple degrees of freedom, introduced the basic theory of welded steel frame with real modal analysis, analysis of welding the weld on the dynamic properties of the theoretical analysis and experiment related analysis theory. 3. Based on the free vibration equation of the beam, as well as the natural frequency formula to set the impact factor of ξ, deduced the dynamic stiffness equation in the fundamental frequency, and theoretical analysis of the relevant factors which affect the vibration frequency, summed up the relevant factors relationships about vibration of the beam frequency, elastic modulus of materials,beam section of inertia beams and the beam span.4. While achieving the eight steel beams with the welded rate of15.15%,27.88%,53.35%,73.96%,100.00%have found in five different welded length, Proceeding Steel frame dynamic characteristics of the experiment. Use DASP modal analysis software collect eight steps former, modal data, and welding rate of100.00%welded steel framework as compared with other four welded rate of steel frame modal datas, which were analyzed by analysis of experimental data to be solved question:a. Dynamic stiffness of the influence law of a different welding rate on steel frame; b. The frequency effects of on the steel frame under different welding rate, and preliminary estimate its impact factor. c. The modal shape effects of on the steel frame under different welding rate. d. Proceeding steel frame damping ratio data chart comparison analysis, and then discusses welding defects of steel frame mode of damping influence law under different welding rate. e. Compare to the results of ANSYS analysis by Liu Huanyu students, analyze its similarities and differences.