Strain Path Control and Defect Formation and Suppression During Forming of Highly Contoured Composite Parts Using Active Tooling

复杂的产品需要大量的高性能部件，这是航空航天工业的特点，但这种产品的复杂性与极低的批量生产能力形成了鲜明对比。对于航空航天应用，先进的复合材料提供了许多优于金属的优点，包括相对较高的比强度和弹性系数，这可以导致形状和微观结构的定制，以满足性能要求。不幸的是，复合材料部件在该行业中的使用受到了先进复合材料部件高昂的制造成本和时间的严重限制，以及需要以高昂的费用储存和维护许多未充分利用的模具。为响应这一需要，目前正在考虑使用主动离散模具(即，在成形过程中基于电子存储几何形状改变形状的销钉矩阵刀具)用于复合材料成形。最近，PI已经成功地证明：(1)使用主动工具进行复合材料成形是可能的；(2)它增加了可以通过成形工艺成功制造的部件的数量。此外，由于使用了单一的可重构工具，极大地简化了模具的开发和存储。这项由国家科学基金资助的为期3年的项目将寻求对使用主动模具的复合材料成型过程有一个基本的了解，特别强调工艺变量对零件成形性和纤维重新取向的影响。研究将集中于工艺开发，并开发数学模型和数值建模方案，将成形复杂形状所需的材料变形模式与先进的成形技术和几何特征联系起来。该项目包括诺斯罗普·格鲁曼公司在材料测试、复合材料成型方面的专业知识以及获得更大的可重构工具方面的支持，从而使技术更快地转移到航空航天行业。此外，该建议还包括本科生的参与(REU)以及将研究作为案例研究、学期设计项目和实验室练习纳入具体的本科生和研究生课程。总体而言，建议的研究有可能显著改善零件的成形性，并减少工艺时间和成本，从复合材料板材成形相对较大的零件。这可以从航空航天扩展到专门的汽车、海洋和生物医学应用。这项研究还将改进复合材料成型的模拟，这是目前复合材料扩大使用的主要障碍。

Complex products requiring a large number of high-performance parts characterize the aerospace industry, but this product complexity is contrasted by an extremely low volume throughput. For aerospace applications, advanced composite materials offer a number of advantages over metals including relatively high specific strengths and elastic moduli, which can lead to tailoring of shape and microstructure to meet performance requirements. Unfortunately, the use of composite parts in this industry has been severely limited by the prohibitive fabrication cost and time of advanced composite component, along with the need to store and maintain many under-utilized molds at great expense. In response to this need, the use of active discrete tooling (i.e., matrix of pins tooling that changes shape during the forming process based on electronically stored geometry) for composites forming is currently being considered. Recently, the PIs have successfully demonstrated that (1) composite forming using active tooling is possible and (2) it increases the number of components that can be successfully manufactured by the forming process. In addition, mold development and storage is greatly simplified because a single reconfigurable tool is used. This 3-year project sponsored by the National Science Foundation will seek to develop a fundamental understanding of composites forming process with active tooling, emphasizing particularly the effects of process variables on part formability and fiber reorientation. The research will concentrate on process development and on developing mathematical models and numerical modeling schemes that relate the material deformation modes necessary to form complex shapes, to advanced forming techniques and geometric features. The project includes support from Northrop Grumman in the form of materials testing, expertise in composites forming, and access to a larger reconfigurable tool, resulting in more rapid technology transfer to the aerospace industry. In addition, the proposal includes involvement of undergraduates (REU) and the integration of the research into specific undergraduate and graduate courses as case studies, semester design projects, and laboratory exercises. Overall, the proposed research has the potential to significantly improve part formability and reduce process time and cost for low to medium volume forming of relatively large parts from composite sheet. This can extend beyond aerospace to specialized automotive, marine, and biomedical applications. The research will also lead to improved simulation of composites forming, which is currently a major barrier to expanded use of composites.