Liquid Composite Molding

该奖项的研究目标是促进使用液体复合模塑(LCM)工艺制造三维(3D)复合材料的制造科学。在LCM中，将由多层二维织物或一层或两层3D织物组成的纤维预制件放置在封闭的模具中，并通过真空或/和正压浸渍树脂，以覆盖预制件纤维之间的所有空隙。复合材料中的任何空隙都可能对其性能有害。根据该奖项，(I)将开发3D预制件渗透性表征的模型和测量技术，并将其用于特拉华大学开发的模拟软件中，以描述液体复合材料模塑中净形状和复杂结构中的树脂流动(Ii)我们的建模和模拟工作将通过流动可视化实验得到验证，(Iii)将制定一种方法来逆转模拟过程，从而不是针对已知的预制件特性来模拟流动，而是将制定渗透率图来确保坚固无空隙的填充。然后可以使用该渗透率图来设计3D预制件，该3D预制件对工艺参数不敏感，并且提供所需的机械性能。交付成果将包括3D预制件渗透率的表征方法、模拟3D复杂复合结构中流动的分析工具、创建渗透率图的反向模拟方法、研究结果的文档记录、工程学生教育以及高中教师的工程研究经验。如果成功，这项研究的结果将允许工艺设计师将现有的流动模拟工具应用于三维预制件。其次，本研究将建立模拟反演的方法，以形成渗透性图，该图可转化为可制造和用于复合材料结构制造的预制件结构，从而提供预制件设计不仅要关注性能而且要考虑制造简单性的新范式。一旦人们很好地了解了3D预制件的特性，它们将被广泛接受，实现其在从变速器外壳到桥梁和梁等基础设施应用的一系列应用中的潜力。3D预制件的使用还将减少LCM中铺层的手工劳动，在LCM中，只需几块先进的3D预制件材料就足够了，而不是放置数百甚至数千层单独的布料。此外，由于这些预制件是近净形状，与裁剪、省道、悬垂和以其他方式操纵布料放置相关的触摸劳动几乎被消除，从而确保了可靠性和可重复性。结果和技术将被转移到与特拉华大学复合材料中心合作的行业，以允许创建改进的3D预制件，以降低成本、缩短原型开发时间和提高可靠性，从而为所需的应用量身定做性能。工程专业的研究生和本科生将从课堂教学和参与研究中受益。高中生和教师将被邀请为他们提供研究经验。

The research objective of this award is to further the manufacturing science of three dimensional (3D) composites fabricated using Liquid Composite Molding (LCM) processes. In LCM, a fiber preform consisting of many layers of two dimensional fabrics or one or two layers of 3D fabric is placed in a closed mold and resin is impregnated by vacuum or/and by positive pressure to cover all the empty spaces between the fibers of the preform. Any voids in the composite can be detrimental to its properties. Under this award (i) models and measurement techniques for permeability characterization of 3D preforms will be developed and used in a simulation software developed at the University of Delaware to describe resin flow in net shape and complex structures in Liquid Composite Molding (ii) Our modeling and simulation efforts will be validated with flow visualization experiments and (iii) A methodology to inverse the simulation process will be formulated so instead of simulating the flow for known preform properties, a permeability map to ensure robust filling without voids will be developed. This permeability map can then be used to design the 3D perform which is insensitive to processing parameters as well as provide the desired mechanical properties. Deliverables will include a characterization method for permeability of 3D preforms, analysis tools to simulate flow in 3D complex composite structures, inverse simulation methodology for creating permeability maps, documentation of research results, engineering student education, and engineering research experiences for high school teachers.If successful, the results of this research will allow the process designer to apply the existing flow simulation tools to three dimensional preforms. Secondly, this research will create methodologies for the inversion of the simulation to formulate the permeability property map which can be translated into preform architectures that can be manufactured and used in fabrication of composites structures thus providing a new paradigm that preform design should not only focus on performance but also on ease of manufacturing. Once the properties of 3D preforms are well understood they will be accepted into general use, fulfilling their potential in range of application from transmission housings to infrastructure applications such as bridges and beams. Use of 3D preform will also lead to reduction in hand labor for ply layup in LCM, where instead of placing hundreds if not thousands of individual layers of fabric, only a few pieces of advanced 3-D preform material is sufficient. Further still, as these preforms are near-net shape, the touch labor associated with cutting, darting, draping, and otherwise manipulating fabric placement is almost eliminated, ensuring reliability and repeatability. The results and the technology will be transferred to industries that work with the Center for Composite Materials at the University of Delaware to allow the creation of improved 3D preforms that have tailored properties for the desired application with reduced cost, reduced prototype development time, and improved reliability. Graduate and undergraduate engineering students will benefit through classroom instruction and involvement in the research. High School students and teachers will be engaged to provide them with research experience.