空间域和时间域共同调控下非均匀板材空间异质性磁流变弹性体软模成形机理与变形协调控制方法

The controlling for deformation coordination will face new problem of thickness variations in the multiple directions and lower plasticity when the tailored blanks tended to develop into the tailor rolled blank with thickness variations in multiple directions and dissimilar tailor welded blanks of lightweight metal Al-Mg, Al-Ti. It leads to new challenges in controlling of deformation coordination of the tailored blanks and its formability. In order to overcome the uncoordinated deformation for the tailored blanks, an innovative method that can regulate and control simultaneously deformation of the tailored blanks in both space and time domain was presented in the project. Combined spatial heterogeneity of the magnetorheological elastomer, i.e. uniform distribution as well as nonuniform spatial distribution of magnetic particles, with a time-dependent magnetic field by which inducing high sensitive magnetorheological effect, uniform distribution as well as nonuniform spatial distribution of mechanical properties was produced in the magnetorheological elastomer. Spatial heterogeneous magnetorheological elastomer is used as flexible-die for the tailored blanks forming. Using spatial heterogeneous and time-dependent properties of magnetorheological elastomer flexible-die to matches difference forces required by different sections in sheet thickness and/or mechanical property of the tailored blanks, it is achieved that the appropriate matched force is appied in corresponding sections of the tailored blanks with different sheet thickness and/or mechanical property. It, on the one hand, depresses faster and larger uncoordinated deformation of the section of thinner sheet or lower strength materials, on the other hand, improves slower and smaller uncoordinated deformation of the section of thicker sheet or higher strength materials. These processes can solve the problems of uncoordinated deformation and lower formability of the tailored blanks and complicated parts.

针对非均匀板材向新型式（多方向连续变截面差厚板）、轻质材料组合（铝-镁、铝-钛）方向发展，变形协调性控制问题出现了多方向、低塑性的新特征，给非均匀板材变形协调控制和成形性带来新的挑战。本项目提出了一种可同时实现空间域和时间域共同调控板材变形的新方法，利用磁流变弹性体磁性粒子密度既可均匀分布又可非均匀分布的空间异质性而带来的力学性能既可均匀分布又可非均匀分布的特性，以及响应灵敏的磁流变效应，选择空间异质性磁流变弹性体作为成形软模，使软模具有的随时间可调控的力学性能非均匀空间分布与非均匀板材厚度或力学性能不同部分变形所需作用力相匹配，实现对非均匀板材不同部分变形施加相匹配的合理的作用力，一方面抑制厚度较薄或强度较低部分变形相对过早、过大的不协调性以及失稳起皱或局部减薄，另一方面改进厚度较厚或强度较高部分变形相对滞后、过小的不协调性，以期解决非均匀板材及复杂形状零件变形不协调、成形性低的问题。

针对板材成形变形协调性控制问题出现的多方向、低塑性新特征，给非均匀板材变形协调控制和成形性带来新的挑战。本项目提出了一种可同时实现空间域和时间域共同调控板材变形的新方法，利用磁流变弹性体磁性粒子密度既可均匀分布又可非均匀分布的空间异质性而带来的力学性能既可均匀分布又可非均匀分布的特性，以及响应灵敏的磁流变效应，选择空间异质性磁流变弹性体作为成形软模，使软模具有的随时间可调控的力学性能非均匀空间分布与非均匀板材厚度或力学性能不同部分变形所需作用力相匹配，解决非均匀板材及复杂形状零件变形不协调、成形性低的问题。主要研究内容包括：空间异质性磁流变弹性体软模制备及力学性能、随时间变化磁场作用下非均匀板材空间异质性磁流变弹性体软模胀形实验（空间域调控+时间域调控）、磁流变弹性体软模的空间异质性和磁场加载方式的优化、非均匀板材空间异质性磁流变弹性体软模成形时在空间域和时间域共同调控下成形性提高的机理等，研究发现采用磁流变弹性体软模可显著提高金属板材的成形性，磁性粒子体积分数为在一定范围内，磁流变弹性体的弹性模量变化范围可以达到一个数量，实现对板材成形状态的实时调控，奠定了板材智能成形的基础，其应用潜力巨大；建立的板材磁流变弹性体介质软模成形过程数值分析方法，实现了磁流变弹性体介质空间异质性能对板材成形性影响的定量化分析，解释了磁流变弹性体介质中空间分布的磁性粒子在外加载磁场随时间作用下的力性变化影响板材成形性的核心问题，为设计磁流变弹性体介质软模结构、制备磁流变弹性体介质软模、研发板材磁流变弹性体介质软模成形技术提供了依据和手段；揭示了磁流变弹性体软模提高金属板材成形性的机理，给出了板材磁流变弹性体软模成形极限图，为今后磁流变弹性体软模的应用和发展提供了理论基础。