The Thermal-Mechanical Coupling Finite Element Analysis Of Heating Roll Forming

In recent years,"strengthening environmental protection, advocating energy conservation and emission reduction to achieve sustainable development" has become the mutual concern of the worldwide people with the world’s energy shortage and increasingly serious environmental pollution problems. Research shows that both the vehicle fuel consumption and exhaust emissions decreases with the vehicle loses weight, so the automobile lightweight are attracting more and more attention. Compared with aluminum magnesium alloy or composite materials, the high strength steel sheet or advanced super-high strengh steel, which can achieve auto lightweight and increase the collision safety performance, are increasingly being applied in the automobile industry. The higher the strength, the worse the plasticity and the elongating decreases as the strength increases, and it is difficult to form, is more likely to fracture or crack and other defects. This paper proposes solutions by employing laser assisted heating roll forming which possesses of high precision> small rebound low forming force and other features, and the capable forming strength is as high as1500MPa. The huge development potential of thermal roll forming makes the research of studying thermal forming rule significant. This paper started the research on the temperature and stress field law of laser assisted heating roll forming under this contest. In order to accurately master the forming law of the heating roll forming, this paper employed the finite element method to obtain the temperature field and residual stress of the heated sheet by using Abaqus software.There are mainly two thermal analysis methods in Abaqus:completely thermal-mechanical coupling and sequent thermal-mechanical coupling, based on the thermal conduction differential equation and the generation principle of thermal stress, this paper adopts sequent thermal-mechanical coupling method and uses the laser heating typical heat source model to conduct the thermal-mechanical coupling finite element analysis of the laser assisted local heating roll forming according to the characteristics and principle of heating roll forming.This paper establishes the correct temperature field model and chooses the appropriate analysis Steps for the laser assisted local heating flexible roll forming process whose Mesh type is DC3D8, the local heating are realized by directly giving certain temperature condition or by applying laser double ellipsoid moving heat source model in the Dflux subroutine, then the temperature field is obtained. Afterwards the stress analysis model is set up, where the analysis type is "General, Static" the Mesh type is changed into C3D8I and the grid density must not be changed, the obtained temperature field is added to the subsequent stress analysis in the manner of predefined form. After being submitted and dealt with, the stress-strain curvy and the strain energy curvy are obtained by using the Static implicit algorithm, the thermal stress is also gotten. Compared with the relevant literatures, the established finite element model the temperature field analysis results in this article are correct, which can provide theoretical foundation for the thermal-mechanical coupling analysis of the laser assisted local heating flexible roll forming, and has vital guiding significance for the production practice.