Specialized finite elements for numerical simulation of the flexibly-reconfigurable roll forming process
Specialized finite elements for numerical simulation of the flexibly-reconfigurable roll forming process
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DOI：
10.1016/j.ijmecsci.2018.11.002
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发表时间：
2019-02-01
影响因子：
7.3
通讯作者：
Kang, Beom-Soo
中科院分区：
文献类型：
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作者：
Ghiabakloo, Hadi;Kim, Jeong;Kang, Beom-Soo
柔性可重构辊弯成形（FRRF）技术是近年来为满足现代制造业对低成本、小批量甚至单批量生产双曲面板材的需求而提出的。在FRRF中，通过使用具有非恒定辊隙的两个弯曲辊来使金属板变形，其中将轧制和辊弯机制强加在一起。由于FRRF工艺，模具制造的成本降低了;然而，工艺设计的计算成本变得很大，因为每个设计可能用于几个甚至单个生产。因此，净生产率由计算时间控制，该计算时间可以比成形时间长几倍。本研究针对纤维增强复合材料的变形机理，试图建立一种准确、高效的纤维增强复合材料的分析方法。这是通过一个高效的有限元方法的内部MATLAB实现和测试元素和变分公式（混合和不可约）的各种组合，以找到它们的最佳组合的数值模拟FRRF。为此，首先进行一系列初步比较，以选择：（1）不可约公式单元的最佳积分方法，（2）混合公式单元节点参数中应包含的最佳应力分量，（3）至少在两个方向上具有非线性插值的单元的最佳单元类（Serendipity或Lagrangian）。然后，通过比较数值模型参数范围内的模拟结果，为每个元素族确定最佳变分公式。最后，有限元模型参数优化为每个候选人的替代为基础的帕累托优化方法，并选择最佳的元素/配方对所有的候选人之间的技术，通过相似性的偏好顺序的理想解决方案（TOPSIS）。此外，为了确定在FRRF过程的分析和设计中最具决定性的参数，FRRF的几个工艺参数，包括厚度，宽度，辊的曲率半径，辊缝分布，和材料性能的变化的响应进行了研究，并与其他研究报告的结果进行了比较。
Flexibly-reconfigurable roll forming (FRRF) process is suggested in recent years as a response to the needs of modern manufacturing industries for small-lot or even single-lot production of doubly-curved sheet metal surfaces with reduced costs. In FRRF, a sheet metal is deformed by the use of two bent rollers with non-constant roll gap where the rolling and roll-bending mechanisms are imposed together. Thanks to FRRF process, the costs due to the manufacturing of dies are reduced; however, the computational cost for process design becomes significant as each design may be used for a few or even a single production. Hence, the net production rate is controlled by computational time that can be several times longer than the forming time. Considering the deformation mechanism in FRRF, this study tries to specialize an analysis method to FRRF that is accurate and efficient. This is accomplished by an in-house MATLAB implementation of an efficient finite element approach and testing various combinations of elements and variational formulations (mixed and irreducible) to find the best combination of them for numerical simulation of FRRF. For this purpose, first a set of preliminary comparisons are made to select: (1) the best integration method for the elements with irreducible formulation, (2) the best stress components to be included in the nodal parameters for the elements with mixed formulation, and (3) the best elemental class (Serendipity or Lagrangian) for the elements with nonlinear interpolation in at least two directions. Then, the best variational formulation is decided for each elemental family by comparing the simulation results in a range of numerical model parameters. Finally, the FE model parameters are optimized for each candidate by a surrogate-based Pareto optimization method, and the best element/formulation couple is selected among all the candidates by the technique for order of preference by similarity to ideal solution (TOPSIS). Moreover, in order to identify the most decisive parameters in the analysis and design of FRRF process, the response of FRRF to variation of several process parameters including thickness, width, rollers' curvature radius, roll gap distribution, and material properties is investigated and the results are compared with those reported by the other studies.