Liquid Composite Molding

该奖项的研究目标是进一步利用液态复合成型（LCM）工艺制造三维（3D）复合材料。在LCM中，由多层二维织物或一层或两层三维织物组成的纤维预制体被放置在封闭的模具中，树脂通过真空或/和正压浸渍以覆盖预制体纤维之间的所有空白空间。复合材料中的任何空隙都可能损害其性能。根据该合同，(i)将开发用于3D预成型渗透率表征的模型和测量技术，并将其用于特拉华大学开发的仿真软件中，以描述液体复合成型中净形状和复杂结构的树脂流动；（ii）我们的建模和仿真工作将通过流动可视化实验进行验证；（iii）将制定一种方法来逆向模拟过程，而不是模拟已知的流动预成型性能，渗透率图，以确保坚固填充无空隙将开发。该渗透率图可用于设计对加工参数不敏感的3D性能，并提供所需的机械性能。交付成果将包括3D预制件渗透率表征方法、模拟3D复杂复合结构流动的分析工具、创建渗透率图的逆模拟方法、研究成果文档、工程学生教育和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人员将现有的流动模拟工具应用于三维预制件。其次，本研究将创建模拟反演的方法，以制定渗透性属性图，这可以转化为可制造和用于复合材料结构制造的预制体结构，从而提供一个新的范式，预制体设计不仅要关注性能，还要关注制造的便利性。一旦3D预制件的特性被很好地理解，它们将被广泛使用，在从传输外壳到桥梁和梁等基础设施应用的应用范围内发挥其潜力。3D预制体的使用还将减少LCM中铺层的手工劳动，而不是放置数百甚至数千层单独的织物，只需几块先进的3D预制体材料就足够了。此外，由于这些预制件是接近净形状的，因此几乎消除了与切割、省道、悬垂和其他操作织物放置相关的触摸劳动，从而确保了可靠性和可重复性。研究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预成型，这些预成型具有针对所需应用的定制特性，同时降低了成本，缩短了原型开发时间，提高了可靠性。研究生和本科生将受益于课堂教学和参与研究。高中学生和教师将参与其中，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.