中厚船舶钢板激光弯曲成形几何效应的数值模拟

建立板材激光弯曲的三维非线性准静态弹塑性热力耦合有限元模型。使用有限元软件 MSC Marc对中厚船舶钢板的激光弯曲成形过程进行数值模拟。计算了船舶钢板激光弯曲成形过程的温度场和变形场, 并进行相应的实验验证。模拟结果与实验结果吻合较好。用建立的模型对中厚船舶钢板的激光弯曲成形过程中钢板的几何效应进行数值模拟, 讨论了一定工艺条件下钢板几何参数与弯曲角度之间的关系, 为在将来实际生产中制定和优化钢板激光弯曲成形的工艺参数提供理论依据。     

板材激光弯曲成形数值模拟的研究现状及展望

板材的激光弯曲成形是一种利用高能激光束扫描金属板材表面产生非均匀分布的热应力，从而使板材发生塑性变形的金属板材柔性成形新工艺，数值模拟已逐渐成为板材激光弯曲成形研究中的热点内容，综述了近年来国内外对激光弯曲成形过程的温度场及变形场进行数值模拟的研究现状，并对其应用范围和发展前景作了展望。     

双相高强钢板的激光弯曲成形数值模拟

为了探究汽车车身用DP980双相高强钢板的激光弯曲成形特性以及激光参数对弯曲角的影响,利用ABAQUS有限元分析软件对DP980双相高强钢板的激光弯曲成形过程进行了数值模拟,研究了激光扫描过程中板材内部的温度场分布,揭示了DP980钢板激光弯曲成形的机理;并对激光功率、扫描速度、线能量等激光参数对板材弯曲角的影响进行了分析。结果表明,DP980双相高强度钢板的弯曲角随着激光功率的增加而增加,随着扫描速度的增加而减小,在一定的线能量范围内,弯曲角大小与线能量呈线性增长关系,并推导出了用于预测钢板弯曲角的数学模型。     

三维激光弯曲成形研究的新进展及发展趋势

综述了三维激光弯曲成形的最新研究动态及发展趋势，论述了三维激光弯曲成形过程中激光扫描策略对成形的影响，分析了扫描路径的变化对典形零件的成形规律，同时分析了管状零件激光弯曲的影响因素及成形规律。最后综述了激光弯曲成形应用于工业的关键因素及发展前景。     

耐热不锈钢板材激光弯曲成形温度场有限元分析

通过建立激光板料弯曲三维热力耦合模型,对1Cr17Ni2耐热不锈钢板材在激光弯曲成形过程中温度场进行了有限元模拟,研究了板料上下表面的温度随时间的变化规律,研究结果表明1Cr17Ni2不锈钢板材的成形机理符合温度梯度机理.     

铜合金薄板的脉冲激光弯曲成形数值分析与实验

借助有限元方法研究C194铜合金薄板的脉冲激光弯曲成形。建立脉冲激光弯曲成形的热力耦合分析模型,解决了激光热源加载、求解稳定性和精度控制等关键技术;对多点脉冲激光弯曲成形进行有限元模拟,通过对模型的温度场、应力/应变场和位移场的动态变化和稳态分布的分析,揭示了其成形机理和规律,薄板的整体弯曲成形是所有脉冲变形效应的叠加结果,且变形量与脉冲次数有着明显的线性关系。实验结果表明,数值分析结果与实验结果有较好的一致性。     

激光弯曲工艺中板材厚度的影响规律

用大变形弹塑性有限元法对金属板材柔性成形新工艺———激光弯曲进行了动态数值模拟。从热学及热力学的观点出发,阐明了该工艺的变形机理,建立了弯曲过程中的应力模型;论证了板料厚度对温度梯度和弯曲角度的影响,提出了能够实现激光弯曲工艺的最小相对光束半径的新概念,为该工艺进一步深入研究奠定了基础。模拟结果与试验吻合较好。     

单曲率板材激光弯曲成形过程的有限元模拟

利用有限元软件MSC.Marc建立了单曲率板激光弯曲成形过程的热力耦合有限元模型。计算并分析了激光弯曲成形过程中板材内部的温度场、应力场和位移场。此外,还研究了扫描线的长度和单曲率板的初始形状对激光弯曲成形的影响。结果表明:随着扫描线长度的增加,板材的弯曲变形量增大;随着单曲率板曲率的增加,板材的弯曲变形量减小。实验结果验证了模型的可靠性。     

汽车底盘纵梁多工步成形数值模拟及试验

采用有限元分析软件,对汽车底盘纵梁的弯曲成形、预成形及内高压成形工艺过程进行了数值模拟。研究内容为,在弯曲成形工步中,管坯各个弯曲位置在相同弯曲半径、不同弯曲角度下的壁厚分布;在预成形工步中,管坯压扁过程中弯曲位置的减薄问题;在内高压成形工步中,优化后的压力加载路径对最终成形零件壁厚的影响。基于有限元模拟结果,分别进行了弯曲成形、预成形和内高压成形试验。结果表明,弯曲成形、预成形和内高压成形弯曲叠加处最易破裂;通过改变模具圆角半径可避免破裂缺陷。实际成形试验结果与数值模拟结果基本一致。     

激光弯曲工艺板材厚度的影响规律

用大变形弹塑性有限元法对金属板材柔性成形新工艺－激光弯曲进行了动态数值模拟。从势学及热力学的观点出发,阐述了该工艺的变形机理,建立了弯曲过程中的应力模型;认 了板料厚度对温度梯度和弯曲角度的影响,提出了能够实现激光弯曲工艺的最小相对光束的新概念,为该工节进一步深入研究奠定了基础。模拟结果与试验吻合较好。     

17型锻造钩尾框热弯曲成形过程数值模拟

介绍了17型钩尾框锻造工艺中弯曲工步的成形过程,应用PROE软件对钩尾框弯曲锻件进行三维实体造型,并用Deform-3D模拟软件对钩尾框弯曲成形过程进行了三维有限元分析,优化了钩尾框锻造工艺.模拟结果表明,优化后的钩尾框锻造工艺过程设计合理,工件能够良好成形,表明三维有限元分析在锻造行业具有一定的应用价值.     

材料性能波动下高强TA18钛管绕弯过程截面畸变行为分析

为了研究材料性能参数对管材数控绕弯过程截面畸变的影响规律及敏感性大小,基于ABAQUS非线性有限元平台,建立了高强TA18钛管数控绕弯成形过程有限元模型,并通过文献中的实验结果验证了模型的可靠性,然后采用该模型模拟研究了材料性能波动下高强TA18钛管数控绕弯成形过程的截面畸变行为。结果表明:截面畸变率随着弹性模量、硬化指数的增加或强度系数、厚向异性指数的减小而减小,其减小率分别为11.76%,23.67%,12.07%和23.51%;不同材料性能参数波动下,高强TA18钛管绕弯过程截面畸变率的最大值均小于4.00%,并且在弯曲平面附近,截面畸变率出现负值;截面畸变率对材料性能参数的敏感性大小依次为强度系数、弹性模量、硬化指数和厚向异性指数。     

U75V重轨冷却过程的相变变形

重轨在轧后冷却时,因固态相变会发生弯向轨底和弯向轨头的复杂弯曲变形,文章采用ANSYS软件对U75V重轨的冷却过程进行数值模拟,得到了U75V重轨冷却过程中的温度变化规律和弯曲变形规律,从理论上对重轨在冷却过程中出现的复杂弯曲变形过程给出了合理的解释;应用后处理模块对计算结果进行处理,计算出冷却后重轨的弯曲曲率半径,计算结果与现场实际情况基本相符。该研究对百米高速重轨冷床的设计和冷却工艺参数的制定,具有重要参考价值。     

基于测试与仿真的数控折弯机滑块刚性分析

板料折弯机的滑块在折弯加工过程中会产生向上的弹性变形,导致折弯时模具之间压力分布不均匀,从而影响工件的折弯精度,因此滑块的刚性分析非常重要。运用应变电测技术与有限元仿真相结合的方法对某型号数控折弯机滑块的变形分别进行了实验测试和有限元计算,并将测试结果与计算结果进行比较,以验证有限元模型的正确性。在此基础上,将滑块高度与厚度作为设计变量,对滑块进行改进设计。改进设计结果表明:将滑块厚度增加20 mm、同时将高度增加100 mm时,滑块刚性得到了明显的提高。     

Numerical investigation on the laser bending of stainless steel foil with pre-stresses

In this paper, a new laser bending process of stainless steel foils with applied pre-stresses is presented. Three different loading models are analyzed. The desired pre-stress distribution in the heated zone of the stainless steel foil is obtained. Using the thermal elastic–plastic finite element method (FEM), the 3D thermal–mechanical FEM models of laser bending process with various pre-stresses are developed and the forming mechanism is analyzed. The simulation results show that under buckling mechanism, the deformation of the stainless steel foil depends on the integration of the thermal stress and the pre-stress when the laser beam irradiates the foil. The forming performance can be improved significantly under pre-stress, and the deformation direction can also be controlled easily by changing the direction and value of the pre-loading. The bending angles of the stainless foils increase remarkably with the increase of the pre-loading, and both are almost in linear relationship.     

Bending with upsetting of copper tube elbows

The purpose of this paper is to determine the basic parameters of copper elbow bending process: the value of the bending moment, the type and degree of deformation of cross-section and change of the wall-thickness for the bending process with and without participation of the axial upsetting force. The effect of axial upsetting force on the above mentioned parameters was determined. The results of calculation of the changes of outer wall-thickness were compared with the results of experimental measurement in the case of bending with and without upsetting when using both the simple and special mandrel.     

Effect of prestressed ultrasonic peen forming parameters on bending curvature and spherical deformation of plate

The elastic prestressed ultrasonic peen forming (UPF) was adopted in order to solve problems of insufficient bending deformation and large spherical deformation of plate during free UPF. The theoretical analysis of prestressed UPF and the influence of elastic prebending moment on deformation were analyzed. Spherical deformation coefficient was defined to quantificationally describe the spherical deformation. Experiments were conducted to compare the differences between free UPF and prestressed UPF processes and the effects of processing parameters on bending curvature and spherical deformation coefficient were studied. The results show that peening trajectory in chordwise direction is beneficial to enlarging spanwise bending deformation and decreasing spherical deformation coefficient. Large prebending curvature is helpful to increase spanwise bending deformation and decrease chordwise deformation, thereby obviously decreasing spherical deformation coefficient. Large spanwise deformation can be obtained under large firing pin velocity, small plate thickness and small offset distance. Large firing pin velocity plays a positive role in decreasing spherical deformation, while plate thickness and offset distance have little effect on it. Above all, prebending curvature and peening trajectory are the most important factors during prestressed UPF process. This study provides guidance for parameters optimization of prestressed UPF for wing plate with large thickness.     

矩形截面梁热应力弯曲的弹塑性分析解

针对一个被均匀加热的矩形截面梁由于不均匀的冷却过程所引起的弯曲变形问题，本文给出了一个热弹塑性分析解。通过具体的计算结果本文讨论了这种热应力弯曲的发生发展过程及其影响因素。     

AZ31B镁合金板材折弯过程中性层偏移规律研究

有效预测和评估板材变形程度对折弯成形工艺和产品精度控制有着现实的指导意义,且中性层偏移是衡量折弯板材拉压区域不均匀变形程度的重要参数。依据塑性变形理论中微元体应力平衡条件,基于能够体现镁合金拉压不对称性的Yoon2014屈服准则,得到了AZ31B镁合金板材折弯过程中中性层偏移量计算模型,并辅以有限元模拟和相应实验对中性层偏移模型进行验证。结果表明：所建立模型能够对镁板中性层偏移现象进行可靠预测,镁板在折弯过程中,受拉压不对称性的影响,中性层向拉伸侧偏移;折弯后角度越小,中性层偏移量越大,在折弯角度至90°,压下量为40～47 mm之间时的中性层偏移程度最明显。     

Determination of forming limit of a structural aluminum tube in rubber pad bending

Rubber pad bending is a novel technique for producing space frame to reduce the weight of automobiles because it can produce bent profiles with various curvatures in a single production set-up. As in other bending processes, cross-section of the aluminum tube deforms during the process. Such a deformed geometry diminishes bending rigidity, making it inappropriate for a structural use in some cases. Thus, it is important to determine a minimum radius of curvature with sufficient bending resistance. In this study, experimental set-up was developed to investigate deformation characteristics of an extruded rectangular aluminum tube in rubber pad bending. For better understanding of the effect of process parameters such as the material property of rubber and roller diameter, finite element (FE) analyses were also conducted. The ratio of the second moment of inertia of the initial and deformed cross-sections of the tube was introduced as a measure of cross-sectional deformation to represent the variation of bending rigidity of the bent tube. In result, a critical value of sectional deformation and minimum formable radius of curvature with maintaining suitable sectional bending rigidity were, respectively, determined under the present process conditions investigated.