铝合金管弯曲成形表面粗化宏细观耦合建模仿真

Macro-meso Scale Coupling Modeling and Simulation of Surface Roughening in Aluminum Alloy Tube Bending

铝合金管弯曲成形中的表面粗化缺陷严重影响了其表面质量和使役性能,迫切需要探明该成形过程中的表面粗化形成规律以避免此类缺陷的产生。管材弯曲成形宏观有限元模型无法准确描述细观尺度不均匀变形导致的表面粗化行为,而细观力学模型又难以应用到具有复杂加载边界条件的实际成形过程分析。将基于Voronoi图和晶体塑性理论的代表性体积单元(Representative volume element,RVE)细观模型引入宏观有限元模型,建立了铝管弯曲三维宏细观耦合模型,模拟研究5052-O铝管在弯曲过程中的表面粗化特征,系统分析了细观材料参数对弯曲过程表面粗化行为的影响规律。结果表明,晶粒尺寸越小,晶粒内部与晶界附近的应变差值越小,其变形越均匀,能获得越小的表面粗糙度;对于Cube织构和随机织构混合的模型,随着Cube织构含量的增多,弯曲变形后表面粗糙度呈下降趋势;织构分布与加载方式耦合影响表面粗化行为。

The surface roughening defects in aluminum alloy tube bending seriously deteriorate the surface quality and service performance.It is urgent to find out the rules of surface roughening formation during the forming process to avoid the occurrence of such defects.A macroscopic finite element model of tube bending cannot reasonably describe the mesoscale inhomogeneous deformation induced surface roughening behavior,while the mesoscale mechanical model can hardly be applied to the practical forming process with complicated boundary conditions.The representative volume element(RVE)meso-model based on Voronoi diagram and crystal plasticity theory is introduced into the macro finite element model to establish a three-dimensional macro-meso coupling model for aluminum tube bending.Then the above macro-meso coupling model is applied to study the surface roughening characteristics of the 5052-O aluminum tube during bending and systematically analyze the influence of microstructure parameters on surface roughening behavior during bending.The results show that the smaller the grain size,the smaller the strain difference between the grain interior and the grain boundary,the more uniform the deformation,and the smaller the surface roughness;for the model with mixture of Cube texture and Random texture,with the increase of the content of Cube texture,the surface roughness after bending deformation decreases;the coupling between the texture distribution and loading method affects the surface roughening behavior.