The Cutting Process Of High Strength Plate Thickness About Leg Mechanical Behavior Research

The legs of offshore platform support the entire platform and surrounding load, which is the most important nuclear part of the entire platform.The existent residual stress and residual strain in the cutting of steel plate have adverse effects on the quality of the followup welding, reduce the structural strength, and even lead to the hidden trouble of the crack propagation,which is not beneficial to the manufacturing of the platform. Based on the innovative program of graduate students in Jiangsu province, the study of the residual stress and strain distribution rule in cutting process on high strength and big thickness plate of mechanics behavior and the follow-up welding can provide certain guidance function for plate manufacture process for leg.This paper expounds the basic theory of thermal elastic-plastic finite element and analyses the correlation research of cutting process in the rack plate,and how to use the finite element software ANSYS to preheat the numerical simulation. Based on the temperature field superposition principle, it introduces the thickness of the correction coefficient. The paper also establishes the model of proper oxygen cutting plate in double heat source temperature field. The study of the temperature field, strain and stress field was verified the availability of the selected of the heat source model in this paper. And the results of simulation cutting plate appeared according to the experimental data. Rack plate oxyacetylene cutting simulation model is set up as well as the analysis of the results of stress and strain regularity. Finally, to analyze cutting the influence of welding residual stress for the follow-up process, it establishes simulation models of a rack plate with semicircle pipe welding and rack plate butt welding. In order to fit the reality, it adopts multi-layer and multi-pass welding.Through the calculation and analysis research, this paper got the NV E690 of some new property parameters, for example, temperature thermal physical, and resistivity, permeability, etc. Besides, it illustrates the importance of leg rack plates preheating. The NV E690 planks cutting choose whole preheating combining the field process and carbon equivalent calculation formula,preheating temperature being 220℃. The leg rack plates choose local preheating, preheating temperature around 150℃, Using finite element analysis software to simulate the plank cutting and to verify the feasibility of the heat source model, having the best correction coefficient. Also, it has gotten the great thickness of work-piece of heat source model, which can be used on the large thickness of the plate. Then it carries on the numerical simulation on a flat plate cutting and gets the rack plate stress and strain distribution rule by the numerical simulation of rack panels. Then, during the comparative analysis of whether to eliminate the residual stress of leg rack plate cutting, it has gotten the sheet pile legs and does not eliminate the,which have larger impact on subsequent welding residual stress. In the leg rack plate with semicircle pipe welding parts, leg rack plate of tooth root,the values of stress and strain change greatly. It will have adverse effect on the performance of the work-piece. Finally, the welding residual stress of welding stress and strain values with the numerical simulation analysis of the pile legs rack plate in butt welding will change a lot without eliminating. The research of high strength of legs of big thickness plate in the process of mechanics numerical simulation not only reproduces the actual process of pile legs plate cutting, welding, but also provides certain theoretical support for the data of the leg panel manufacturing process.