Integral design and impact damage analysis of a RTM composite multi-spar structure- From coupon to full-scale level

Abstract

The increasing demand of composite materials in aircraft structures leads to the need for new lighter, more integral design, less labour intensive practices that can move the industry into a more economical way of making products in less time. Currently, the conventional way of producing a composite structure is to use resin impregnated material to make multiple parts, which are then cured in an autoclave and assembled to produce the final item, and this creates a complex manufacturing and supply process chain. To decrease manufacturing costs and improve efficiency, an optimised integral design is required to produce fewer parts which are near to net shape. The aim of this work was to combine the RTM (Resin Transfer Moulding) manufacturing process and the newly built concept of developing an integrated box structure, replacing today’s conventional differential spar/rib design found in a composite multi-cell box. The new approach could lead to manufacturing of more complex configurations in less time and cost, with minimum assembly effort. In this thesis a framework is presented which provides guidelines for new out-of-autoclave RTM integral composite design. The framework follows three main paths, the first one is to redefine our understanding of today’s composite design and manufacturing from an industrial perspective. The second, is to produce such parts, covering in detail the manufacturing method. Finally, subject the structure to various impact loadings and compare its mechanical response to standard coupon level test data. This thesis establishes a novel approach to successfully produce a large integrated composite box, and the outcome of drop-weight impact testing on 1:1 scale structure. The results demonstrate that it is possible to reduce the number of plies, hence reducing manufacturing cost, while maintaining the structural requirements defined by the manufacturer. It is also found that testing small samples could be misleading in terms of severity of damage and data cannot accurately describe the response of a large scale configuration but helps in predicting the damage size. The aerospace industry is in need of such full size testing that validates the integral design approach and will enable the building of more complex geometries in the near future, replacing current high-energy demanding autoclave manufacturing.

Date of Award	31 Dec 2021
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Zhenmin Zou (Supervisor), Yong Wang (Supervisor) & Matthieu Gresil (Supervisor)