Investigation of fine-scale flows in composites processing

预计未来20年全球航空旅客将增长90%，这既是挑战，也是机遇。高燃料成本和环境压力意味着人们真实的关注运营经济性，这导致了复合材料的前所未有的增长，复合材料提供了一种轻质的替代品。然而，碳复合材料的成功生产也带来了挑战，因为它需要使用高压釜来最大限度地减少封装纤维的聚合物树脂材料中的间隙（空隙缺陷）。通过开发有效的非高压灭菌（OOA）制造工艺，可以获得更低的资本和运营成本、灵活的加工基础设施、更广泛的供应链和更环保的制造工艺。事实上，高价值制造弹射器最近将面向对象的制造解决方案确定为经济增长的关键领域，以确保英国在下一代飞机机翼、航空推进技术和结构轻量化技术方面的存在，这些技术是帮助政府实现碳减排和排放目标所必需的。该项目将开发实验技术和数值工具来模拟空隙过程，以便在非高压釜条件下生产用于复合材料制造的改进的材料设计。我们打算分析的工艺使用半浸渍碳纤维增强材料，其中聚合物以这样的方式应用，即在加工开始时存在干燥和饱和区域。将研究两个过程：（i）真空袋处理，其中通过大气压力进行固结（低压缓慢地排出截留的气体，适用于较大的部件，例如机翼蒙皮），和（ii）使用机械压力机（高压快速处理使空隙塌陷，适用于较小的部件，例如汽车结构）。半浸渍材料格式的优点是可以使用具有更高工艺粘度的增韧聚合物，并且一旦建立了建模方法，它可以扩展到树脂灌注工艺，只需对模型几何形状和边界条件进行微小修改。该项目的第一阶段是解决一个基本需求，即能够理解和建模形成和消除空隙的过程，从而可以在虚拟环境中以成本有效的方式快速设计这些过程。一旦实现了这种理解的飞跃并创建了合适的工具，第二阶段就是创建定制的材料，以使用手动和自动优化来最大限度地减少真空或压力路线的空隙缺陷的形成。英国目前拥有23亿英镑的综合市场，并希望到2030年将其增长到120亿英镑，这项研究的结果将有助于英国经济中一个至关重要和不断增长的部门。

Anticipated growth in global air passengers by 90% over the next 20 years presents both challenges and opportunities. High fuel costs and environmental pressures mean there has been a real focus on operating economics and this has led to an unprecedented growth in composite materials, which offer a lightweight alternative. Successful production of carbon composites brings its own challenges however, in that it requires the use of autoclaves to minimise gaps (void defects) in the polymer resin material that encapsulates the fibres. This makes the process costly, energy-hungry and slow.Lower capital and operating costs, flexible processing infrastructure, a broader supply chain and a greener manufacturing process represent the big gains that could be made through development of effective out-of-autoclave (OOA) manufacturing processes. Indeed, the High Value Manufacturing Catapult has recently identified OOA manufacturing solutions as a key area for economic growth to ensure a UK presence in next-generation aircraft wings, aero propulsion technologies, and structural light-weighting technologies necessary to help the government achieve carbon-reduction and emissions targets.This project will develop experimental techniques and numerical tools to simulate void processes, in order to produce improved material designs for composite manufacture in out-of-autoclave conditions. The processes we intend to analyse use semi-impregnated carbon fibre reinforcement, where the polymer is applied in such a way that dry and saturated regions are present at the start of processing. Two processes will be studied: (i) vacuum bag processing, where consolidation is by atmospheric pressure (low pressure slowly evacuates entrapped gasses, suitable for larger parts such as wing skins), and (ii) using a mechanical press (high pressure fast process collapses voids, suitable for smaller parts such as automotive structures). The advantage of a semi-impregnated material format is that toughened polymers with higher process viscosity can be used, and once the modelling approach is established, it can be extended to resin infusion processes with minor modifications to the model geometry and boundary conditions.The first stage of this project is to address a fundamental need to be able to understand and model the processes that form and remove voids, so that these processes may be designed quickly in a cost-effective manner in a virtual environment. Once this jump in understanding is made and suitable tools created, the second stage is to create tailored materials to minimise formation of void defects for either the vacuum or press-based routes using manual and automatic optimisation. With the UK currently boasting a £2.3bn composite market, and looking to grow this to £12bn by 2030, the findings of this research will contribute to a vitally important and growing sector of the UK economy.