Hot Drape Forming of Thermosetting Composites

为了使用预浸料（towpreg）自动化生产复合材料零件，已经开发了自动胶带放置（ATL）和自动纤维放置（AFP）技术。许多飞机结构部件，如肋、框架、梁或支架，都太小或形状太复杂，无法使用AFP等自动化技术高效、经济地制造。为了利用自动化技术制造这些零件，提出并采用了两步法。首先通过自动化过程（如ATL或AFP）创建具有正确形状和堆叠顺序的未固化层的扁平堆叠。然后，平堆被转移到成形装置，在固化之前，使用热量和压力（真空）将其变成最终形状。这被称为热垂成型。过程中施加的热量降低了树脂粘度，而压力（真空）提供了形成层压板的机械作用。为了更好地理解层压复合材料的形成过程，需要捕捉过程的物理特性并开发模型。然后利用模型对过程进行模拟和优化。本研究的重点是树脂在成型过程中传递剪切载荷和支撑纤维以防止纤维屈曲和起皱的作用。必须定义加工窗口，以在操作结束时获得高质量的零件。通过这两个步骤的过程，可以探索自动化制造小而复杂零件的全部优势。这将向加拿大航空航天工业展示使用AFP以更低成本制造不同零件的自动化更广泛的优势。

To automate production of composite parts using prepreg (towpreg), automated tape placement (ATL) and automated fibre placement (AFP) technologies have been developed. Many aircraft structural parts such as ribs, frames, spars or brackets are too small or too complex in shape to be efficiently and cost-effectively manufactured using automated technologies such as AFP. To take advantage of the automation (AFP) to manufacture these parts, two-step process is proposed and used. A flat stack of uncured plies with correct shape and stacking sequences is first created by automated processes such as ATL or AFP. Then flat stack is transferred to the forming set-up where it is turned into the final shape using heat and pressure (vacuum) before being cured. This is called hot drape forming. The heat applied during the process reduces the resin viscosity, while the pressure (vacuum) provides the mechanical action to form the laminate. A better understanding of forming process of laminated composite is required to capture the physics of the process and to develop models. Then models can be used to simulate and to optimize the process. Focus of this study will be on the resin role on transferring the shear load and supporting the fibres during the forming to prevent the fibres from buckling and wrinkling. Processing window has to be defined to achieve a good quality part at the end of operation. Through this two steps process, the full advantage of automation for manufacturing of small and complex parts can be explored. This will show the Canadian aerospace industry even broader advantage of automation using AFP for manufacturing different parts at lower cost.