Hot Drape Forming of Thermosetting Composites

为了使用预浸料(TowPreg)实现复合材料部件的自动化生产，已经开发了自动布带(ATL)和自动纤维布放(AFP)技术。许多飞机结构部件，如肋骨、框架、支柱或支架，形状太小或太复杂，无法使用AFP等自动化技术高效和低成本地制造。为了利用自动化(AFP)制造这些零件，提出并使用了两步法工艺。具有正确形状和堆叠顺序的未固化层的扁平堆叠首先由ATL或AFP等自动化工艺产生。然后将扁平堆叠转移到成型装置，在那里，在固化之前，利用加热和压力(真空)将其转变为最终形状。这就是所谓的热悬垂成型。在加工过程中施加的热量降低了树脂的粘度，而压力(真空)提供了形成层压板的机械作用。为了更好地了解层合复合材料的成型过程，需要了解该过程的物理过程并建立模型。然后，可以使用模型来模拟和优化该过程。这项研究的重点将放在树脂在成型过程中传递剪切载荷和支撑纤维以防止纤维弯曲和起皱的作用。必须定义加工窗口，以在操作结束时获得高质量的零件。通过这两个步骤的流程，可以充分发挥自动化制造小而复杂的零件的优势。这将向加拿大航空航天行业展示使用AFP以更低的成本制造不同部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.