高强钢薄板弯曲力学性能研究

发布时间：2019-01-20 16:20

【摘要】：辊弯成形是一种通过轧辊将板材逐渐弯曲成为型材的工艺。目前辊弯成形有限元仿真的材料性能数据主要来自于金属板材拉伸试验得出的力学性能数据,而拉伸力学性能不能够全面准确的表现金属板材在弯曲成形过程中的应力应变状态。在辊弯成形仿真过程中,材料模型的选择对板材最终回弹角度起决定作用。本文设计一种弯曲试验,获得板材弯曲变形时的应力应变数据以提高仿真的准确性。本文首先进行拉伸试验以获得DP980高强钢板材拉伸力学性能。并使用专门设计的弯曲试验装置,将拉伸试验机纵向运动转换为试样的弯曲变形,并配合三维应变测量仪对试样的弯曲变形过程进行测量,得到DP980高强钢板材在弯曲变形时的弯矩曲率特性,并将其弯矩曲率数据转换为板材在弯曲状态下的应力应变数据。建立三点弯、辊弯成形有限元仿真模型,将仿真过程中弯角区应力、应变数据与两侧平板区应力应变数据做对比,分析三点弯与辊弯成形工艺的成形特点。对DP980高强钢板材进行三点弯试验、辊弯成形试验,并与其对应的有限元仿真结果进行对比。结果表明,导入弯曲模型的仿真可以更加准确的预测板材在三点弯、辊弯成形过程中的回弹角度;可知,从弯曲试验得出的力学性能能够更准确的描述以弯曲变形方式为主的三点弯、辊弯成形工艺特性,基于材料弯曲性能数据建立的有限元仿真模型可以提高三点弯、辊弯成形过程仿真的准确性。
[Abstract]:Roll forming is a process in which the sheet metal is gradually bent into a profile by roll. At present, the material performance data of the finite element simulation of roll forming mainly come from the mechanical property data obtained from the tensile test of metal sheet. But tensile mechanical properties can not fully and accurately express the stress and strain state of sheet metal in bending process. In the process of roll forming simulation, the choice of material model plays a decisive role in the final springback angle of sheet metal. In this paper, a bending test is designed to obtain the stress-strain data of sheet metal during bending deformation to improve the accuracy of simulation. In this paper, tensile test was first carried out to obtain tensile mechanical properties of DP980 high-strength steel sheet. With the specially designed bending test device, the longitudinal motion of the tensile testing machine is converted into the bending deformation of the specimen, and the bending deformation process of the specimen is measured with a three-dimensional strain measuring instrument. The bending moment curvature characteristics of DP980 high strength steel sheet during bending deformation are obtained, and the moment curvature data are converted into the stress-strain data of the plate under bending condition. The finite element simulation model of three point bending and roll bending is established. The stress and strain data of corner region are compared with the stress and strain data of both sides of flat plates in the simulation process, and the forming characteristics of three point bending and roll bending forming process are analyzed. The three point bending test and roll forming test of DP980 high strength steel sheet were carried out, and the results were compared with the corresponding finite element simulation results. The results show that the simulation with bending model can predict the springback angle of sheet metal in the process of three-point bending and roll bending more accurately. It can be seen that the mechanical properties obtained from the bending tests can more accurately describe the process characteristics of three-point bending and roll bending, and the finite element simulation model based on the material bending performance data can improve the three-point bending. Accuracy of roll forming simulation.
【学位授予单位】：北方工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG142.14

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