帽型材弯曲截面畸变有限元数值模拟研究

发布时间：2018-10-22 14:27

【摘要】：铝合金薄壁帽型材不仅强度高、质量轻、抗腐蚀性强,同时还能实现工业生产中节能、环保的特点,已被广泛地应用在航空、航天、汽车等高科技领域中。数控绕弯法是此类零件的重要加工方法之一,但由于该成形方法涉及多模具、多因素的耦合作用,使得其在成形过程中容易发生截面畸变、回弹、失稳起皱等缺陷,尤其是截面畸变严重制约着弯曲件的成形质量以及成形精度。因此,本文采用数值模拟技术并结合实验及理论分析的方法对帽型材绕弯成形过程中截面畸变行为进行深入研究,研究内容和结果如下:(1)结合铝合金薄壁帽型材弯曲成形特点,解决了接触、摩擦、加载、边界条件等关键技术问题,建立了铝合金薄壁帽型材绕弯成形三维有限元模型,并验证了该模型的可靠性。(2)采用所建立的可靠模型,研究获得了5052铝合金帽型材绕弯成形过程中应力应变的分布特征,揭示了截面畸变的产生机理,提出了衡量截面畸变的指标。结果表明:随着绕弯进程的进行,型材的等效应力和等效应变逐渐增大;截面变形是型材受到切向拉应力和切向压应力的合力所致,一旦变形超过了其允许的范围,就发展为畸变。(3)研究获得了弹性模量、泊松比、相对弯曲半径、弯曲速度等成形参数对帽型材绕弯成形截面畸变的影响规律。研究表明:随着弹性模量、硬化指数、弯曲模与型材间摩擦系数、压块与型材间摩擦系数、夹块与型材间摩擦系数、相对弯曲半径、压块助推速度的增大,截面畸变呈减小趋势;随着屈服强度、强度系数、弯曲模与型材间隙、压块与型材间隙、夹块与型材间隙、弯曲角度的增大,截面畸变增大;适当增大弯曲速度,有利于减小截面畸变;而泊松比、防皱块与型材间摩擦系数、防皱块与型材间间隙的改变对截面畸变影响不大。
[Abstract]:Aluminum alloy thin-wall cap profile not only has high strength, light weight, strong corrosion resistance, but also can realize the characteristics of energy saving and environmental protection in industrial production. It has been widely used in aviation, aerospace, automobile and other high-tech fields. Numerical control winding and bending method is one of the most important machining methods for this kind of parts. However, due to the coupling action of multi-die and multi-factor, the forming method is prone to the defects of section distortion, springback and buckling. Especially section distortion seriously restricts the forming quality and precision of bending parts. Therefore, in this paper, numerical simulation technique and experimental and theoretical analysis are used to deeply study the section distortion behavior in the forming process of cap profile. The research contents and results are as follows: (1) combined with the characteristics of aluminum alloy thin-walled cap profile bending forming, The key technical problems such as contact, friction, loading and boundary conditions are solved. A three-dimensional finite element model of aluminum alloy thin-walled cap profile is established, and the reliability of the model is verified. (2) the reliability model is adopted. The distribution characteristics of stress and strain in the forming process of 5052 aluminum alloy cap profile are studied. The mechanism of section distortion is revealed and the index to measure section distortion is put forward. The results show that the equivalent stress and strain increase gradually with the bending process, and the cross section deformation is caused by the combined force of the tangential tensile stress and the tangential compressive stress, once the deformation exceeds its allowable range, (3) the influence of forming parameters, such as elastic modulus, Poisson's ratio, relative bending radius and bending speed, on section distortion of cap profile is studied. The results show that: with the increase of elastic modulus, hardening index, friction coefficient between bending die and profile, friction coefficient between press block and profile, friction coefficient between clip and profile, relative bending radius, pushing speed of press block, The section distortion decreases with yield strength, strength coefficient, gap between bending die and profile, gap between press and profile, gap between clip and profile, and section distortion increases with the increase of bending angle, appropriate increase of bending speed, Poisson's ratio, friction coefficient between wrinkle block and profile, and gap between wrinkle block and profile have little effect on section distortion.
【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG306

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