Forming of Composites

许多现代结构，包括主要的航空航天结构、高性能体育用品、船舶和风力涡轮机结构，正逐渐依赖于基于纤维增强热固性和热塑性聚合物的先进复合材料。传统的复合材料制造技术，如手工铺层，是劳动密集型、耗时和昂贵的。对复合材料零件的需求增加，加上其尺寸和复杂性的增加，给传统的加工方法带来了压力，并推动了对快速、自适应和具有成本效益的制造替代方案的需求。自动化铺带(ATL)和自动纤维贴装(AFP)等自动化制造流程的低制造时间和低成本为满足航空航天和汽车行业对复合材料日益增长的需求提供了巨大的希望。这些自动化过程的生存能力的限制因素是它们产生复杂几何图形的能力。为了提高生产率，同时保持部件的几何复杂性，采用了三个步骤的工艺。首先，平层压板是由自动化机器或手工铺设的。然后，对这些层压板进行成形处理。这一成型步骤包括在固化前应用加热和压力将平层压板转换成所需的形状。最后，成形的零件被固化。为了确保复合材料的成功成形，必须彻底了解导致起皱等缺陷的机理。选择合适的工艺条件，控制材料性能，防止面内和面外起皱，决定了复合材料成形的成败。

Many modern structures, including primary aerospace structures, high performance sporting goods, and marine and wind turbine structures, are progressively coming to rely on advanced composite materials based on fiber-reinforced thermoset and thermoplastic polymers. Conventional composite manufacturing techniques, such as hand lay-up, are labor-intensive, time consuming, and costly. Increased demand on composite parts, together with an increase in their size and complexity, puts a strain on traditional processing methods and drives the need for fast, adaptive, and cost-effective manufacturing alternatives. The low manufacturing times and costs associated with automated manufacturing processes such as Automated Tape Laying (ATL) and Automated Fiber Placement (AFP) offer great promise to meet the growing need for composite materials in the aerospace and automotive industries. The limiting factor for the viability of these automated processes is their capacity to produce complex geometries. To improve productivity while maintaining the geometrical complexity of components, a three-step process is undertaken. First, flat laminates are laid down by automated machines or hand layup. Then these laminates are subjected to a forming process. This forming step involves the application of heat and pressure to transform flat laminates into the desired shape prior to curing. Finally, the formed parts are cured. To ensure successful composite forming, the mechanisms that cause defects such as wrinkling must be thoroughly understood. The success of composite forming is determined by selection of proper processing conditions which control the material properties and prevent any in-plane and out-of-plane wrinkling.