Redesigning composite repair process using induction heating

在过去的几十年里，先进复合材料在航空航天工业中的应用以其优越的机械性能呈指数级增长。从经济和可持续性的角度来看，这些材料的最大限制是无法进行时间和能源效率的修复。传统上，损坏的层被替换为层压板或湿铺，然后在整个组件上进行长时间的固化周期。因此，需要一种更局部的固化方法，能够以快速和节能的方式产生原位固化的修复补丁。为了实现这一目标，感应加热将通过体积加热复合材料层压板进行测试，以便在生产原位固化的修复补丁之前更好地了解其效果。初步实验已经实现了碳纤维基层压板和含金属簇的玻璃纤维层压板的快速加热。这些实验表明，加热模式高度依赖于所使用的感应线圈的几何形状。复合材料板的加热在平面和厚度上也存在显著的不均匀性，这可以通过使用新颖的感应线圈几何形状以及具有高导电性的感受器来改善。本研究旨在从固化速率和加热均匀性两方面优化感应固化工艺。利用有限元软件Abaqus的电磁功能进行数值模拟，将为理解线圈几何形状和材料参数对加热剖面的影响奠定基础。这些模型将用于制造感应线圈，随后进行优化过程，以快速固化具有高均匀性的层压板。这种优化的工艺将用于制造与传统方法相比较的修补补丁。该项目的主要目标是：-使用有限元建模对设计变量进行优化，以最大化感应加热的效率和均匀性。-使用基于建模的优化工艺制造复合层压板。-应用实验方法制作原位固化的修补贴片。这项工作的结果应该允许制造复合修复补丁，它可以在现场固化，这将允许修复大型层压板组件，大大节省时间和能源效率的方式

The application of advanced composite materials in the aerospace industry, utilised for their superior mechanical properties, has grown exponentially over the last few decades. The largest limitation of these materials from both an economic and sustainability viewpoint are the inability for time and energy efficient repair. Traditionally, damaged plies are replaced with laminate patches or wet lay ups followed by a long cure cycle over the entire component. Therefore, there is a requirement for a more localised curing method which can produce repair patches cured in-situ in a fast and energy efficient manner.To achieve this, induction heating will be testing by volumetrically heating composite laminates to gain a better understanding of its effects before producing repair patches cured in-situ. Preliminary experiments have achieved rapid heating in carbon fibre based laminates as well as glass fibre laminates containing metallic tufts. These experiments show heating patterns to be highly dependent on the geometry of the induction coil used. There is also a significant non uniformity in the heating of a composite panel both in plane and through thickness which could be improved using novel induction coil geometries as well has highly conductive susceptors.This research aims to optimise the process of induction curing both in terms of rate of cure and uniformity of heating profile. Numerical modelling using the electromagnetic capabilities of Finite Element software, Abaqus, will form the basis for understanding the effect of coil geometries and materials parameters on the heating profile. These models will be used to manufacture an induction coil followed by an optimisation process to cure laminates quickly with high uniformity. This optimised process will be used to manufacture repair patches which will be compared to conventional methods.The key objectives of this project are:-Perform an optimisation of design variables to maximise the efficiency and uniformity of inductive heating using Finite Element modelling.-Manufacture composite laminates using optimised process based on modelling.-Apply experimental methods to produce repair patches cured in-situ.The results of this work should allow manufacture of composite repair patches which can be cured in situ which will allow for repair of large laminate components significantly more time and energy efficient manner