Hot Drape Forming of Thermosetting Composites

为了使用预浸料（丝束预浸料）自动生产复合材料部件，已经开发了自动铺带（ATL）和自动纤维铺放（AFP）技术。许多飞机结构部件，例如肋、框架、翼梁或支架，在形状上太小或太复杂，以至于不能使用自动化技术（例如AFP）高效且成本有效地制造。为了利用自动化（AFP）来制造这些部件，提出并使用了两步工艺。首先通过ATL或AFP等自动化工艺创建具有正确形状和堆叠顺序的未固化层片的扁平堆叠。然后将扁平堆叠转移到成形装置，在那里使用热和压力（真空）将其变成最终形状，然后固化。这被称为热悬垂成形。在该过程中施加的热量降低了树脂粘度，而压力（真空）提供了形成层压材料的机械作用。为了更好地理解复合材料层合板的成形过程，需要掌握成形过程的物理过程并建立模型。然后，模型可以用于模拟和优化过程。本研究的重点将是树脂的作用，转移剪切载荷和支持纤维在成型过程中，以防止纤维屈曲和扭曲。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，可以充分利用自动化在小型复杂零件制造中的优势。这将向加拿大航空航天工业展示使用AFP自动化以更低成本制造不同零件的更广泛优势。

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.