A Study of Friction in Composite Materials Forming

复合材料行业正在迅速发展，以响应通过减轻重量来节约能源和减少排放的需求-特别是在汽车和航空航天等运输部门。许多复合材料零件都是用成形工艺生产的（特别是那些形状不规则的零件）。在这样的过程中，至关重要的是，最终的组件符合设计规范，没有皱纹，空洞和不必要的厚度变化。然而，目前确保成功的唯一方法是提前进行昂贵的试错类型测试。由于零件的几何形状可以定期改变，因此成型行业希望有一个预测工具，可以预测结果，因此可以用来设置最佳的过程，以生产所需的零件。任何预测模型的关键工作都是预测成形力。在成形过程中起作用的重要力之一是摩擦力。为了正确预测成型过程中的摩擦力，必须对摩擦行为有一个基本的物理理解，并且必须对使用相关织物和树脂类型的摩擦响应进行表征。以前已经进行了一些摩擦试验，但这些试验通常是理想化的，或者是在不具有代表性的小接触区域上进行的。该项目将设计实验，在广泛的边界条件下，对不同的织物和树脂系统进行具有代表性的摩擦力测量。将建立一个结果数据库，给出影响摩擦的各种变量（如树脂类型、织物类型、温度、法向载荷和剪切速率等）变化的摩擦响应。工具层和层间摩擦都将被研究。然后，将开发基于实验数据库的ABAQUS用户子程序来模拟接触行为。这种对成形过程中摩擦的预测能力将被添加到我们小组目前可用的成形模型中，以提高他们的成形预测。最后，将模型的预测结果与实验结果进行了对比，并结合实例进行了验证。该项目将产生有价值的成型摩擦的物理描述，相关结果的数据库和预测子程序，可以添加到现有的模型，以提高其准确性。结果将是朝着精确预测成型模型的方向迈出的重要一步，该模型具有显著降低成本和优化产品的潜力。该项目的最后一个方面将是研究在成形过程中减少摩擦的可行方法。

The composite materials industry is rapidly growing in response to the need to conserve energy and reduce emissions by reducing weight - particularly in transport sectors such as automotive and aerospace. Many composite parts are produced using a forming process (especially those with irregular shapes). In such processes, it is essential that the final component meets the design specifications and is free from wrinkles, voids and unwanted thickness variations. At present, however, the only way to ensure success is to carry out costly trial and error type testing in advance. Since the component geometries can change on a regular basis, the forming industry would like to have a predictive tool which can predict outcomes and can therefore be used to set up the process optimally to produce the required part. A crucial job of any predictive model is to predict the forming forces. One of the important forces acting during the forming process is friction. To correctly predict friction forces in forming, an underlying physical understanding of the frictional behaviour must be developed and the frictional response using relevant fabric and resin types must be characterised. Some friction tests have been carried out previously, but these have often been idealised or on small contact areas which are not representative. This project will design experiments to give representative friction force measurements for different fabric and resin systems under a wide range of boundary conditions. A database of results will be established giving the friction response to changes in the various variables affecting friction such as resin type, fabric type, temperature, normal load and shear rate etc. Both tool-ply and ply-ply friction will be investigated. An ABAQUS user subroutine based on the experimental database will then be developed to model the contact behaviour. This predictive capability for friction in the forming process will then be added to presently available forming models within our group to improve their forming predictions. Finally, the model will be validated by comparing predictions with test results for some case-study type forming examples. The project will produce a valuable physical description of friction in forming, a database of relevant results and a predictive subroutine which can be added to existing models to increase their accuracy. The result will be a significant step in the direction of accurate predictive forming models which have the potential to reduce costs considerably and to optimise products. A final aspect of the project will be to look at viable approaches to reducing friction during the forming process.