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Composite tooling for business jet lower wing stiffened panel manufacturing

Periodic Reporting for period 1 - COMBUSS (Composite tooling for business jet lower wing stiffened panel manufacturing)

Reporting period: 2018-11-01 to 2019-12-31

The aim of the COMBUSS project is to develop, design, manufacture and deliver to the Topic Manager (TM) facilities, all the prototype subcomponent manufacturing tooling needed to manufacture the stiffeners and panel of lower wing (including all auxiliary tools). COMBUSS project will design the tooling system which will incorporate self-heated capability with multiple heating zones and advanced thermal management.
For the COMBUSS project the major objective for the first reporting period (P1) was to design a prototype tooling system to produce the composite stiffened panel of the lower wing of a business jet. The design was on M9 of the project after a Critical Design Review (CDR) in collaboration with the TM. The tooling features the following key characteristics:
a. Full functionality for the processing in fewer steps of the integrated stiffened panel design.
b. Lightweight with long service life and flexibility.
c. Built-in quality assurance tools to guarantee reliable processing of the selected material systems according to technical specifications.
d. Tooling documentation for accurate dimensioning, modification protocols and health check during the tool service life.
In order to materialize this outcome, the COMBUSS Consortium has introduced, adapted and validated a set of innovative technologies covering materials, sensors, models, tools and devices. All these technologies will be physically integrated on the prototype tooling, which will acquire the required qualities in manufacturing.
Eventually, COMBUSS aims to develop and demonstrate an innovative tooling configuration for the manufacturing of all components of a composite stiffened panel, while considering sustainable production with integration of innovative modelling, monitoring, and optimization and control systems.
The activities for Period 1 (P1) of the project start with the provision of definitions and specifications by the Topic Manager (TM). The mould materials have been optimised for long life and improved productivity and the COMBUSS system features built-in quality assurance tools to guarantee reliable processing of the selected material systems according to technical specifications. All design works have been completed and the moulding system is at the manufacturing phase.
The project has completed the “Tool design phase”: In the first two technical WPs (WP2 & WP3) the tool design, including all components (heat/cool systems), thermal management, process monitoring, and positioning of inlet/outlet ports has been finalized through a number of iterations.
The concept of the COMBUSS manufacturing system is the use of robust self-heated composite tools for preforming, injection and cure of the stiffened panel components. The composite tools are designed for long life and effectively integrate temperature and material property sensing elements with the view to facilitate control system for low cost, energy efficient and quality assured production of the composite stiffened panels. The main concept of the COMBUSS manufacturing system is the use of robust self-heated composite tools for preforming, injection and cure of the stiffened panel components. COMBUSS concept is depicted in Figure 1. Figure 2 shows the CATIA model of the closed mould for the manufacturing of the stiffened panel and Figure 3 shows the early stages of master mould fabrication.
After the TM’s approval of the design, the tool is being fabricated, will be checked for conformance with the specification and eventually transported to the TM premises and commissioned. The partners will provide full documentation on the tooling system and its use and will support the TM with the demonstrator fabrication.
COMBUSS proposes a composite manufacturing system based on robust self-heating composite tool suitable for resin infusion processing of integrated structures, such as the stiffened panel. The benefit of this approach is the freedom to manufacture the tool with high dimensional accuracy while integrating enabling technologies for multi-zone thermal control with material-state driven support algorithms.
In COMBUSS certain challenges have been addressed as far as the innovative tooling is concerned. The self-heating capability was combined with the requirement of long service life of the RTM tooling. The development of the innovative tool has the following characteristics:
• Several design loops encompassing thermal and processing simulations ensure the soundness of the developed solution. A precise temperature control system s employed that allows for very close following of the optimal temperature profile throughout the part curing. Up to eleven independent heating zones can be utilized.
• The electric sizing is able to heat the part safely at 180°C.
• The resistive elements support possible autoclave post-curing of the tool up to 220°C and max 7 bar.
• The resistive elements possess the required electrical insulation to readily incorporate them in in a composite the conductive structure of the mould without any issues. Initial trials suggest that the system is capable to withstand post curing at 220°C.
• The selection of resistive elements has to take into account the effect of this wire on the tool ageing.
• The use of in-process sensors for the continuous measurement of material properties in the part. This allows rapid adjustment of energy balance in the tooling and on-line quality control of the produced aeronautical composite structures.
• Integration with state-of-the-art process optimization algorithms to establish an eco-efficient curing system.
Currently, one of the major cost items of fiber reinforced composite production is curing. The energy required is very high and can make up close to 50% of the total embedded energy of the final product. Hence, methodologies that reduce the required energy will provide a major opportunity for cost reduction that can lead to:
• Increased appeal of fiber reinforced composites through lower cost
• Reduction of embedded carbon footprint, and
• Improved product quality
COMBUSS is promoting the use of a self-heated fully controlled processing tool that will minimize the required energy budget and offer unparallel quality assurance. In terms of energy savings, payback period of the proposed processing method can be much shorter when compared with conventional oven or autoclave.
CATIA model of COMBUSS Tooling
COMBUSS concept for the development of an innovative tooling system
COMBUSS master mould fabrication stages and metallic frame