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Flexible RTM tool with automated distortion correction

Periodic Reporting for period 1 - FLEX (Flexible RTM tool with automated distortion correction)

Reporting period: 2018-09-01 to 2019-08-31

The FLEX proposal answers to the scope of JTI-CS2-2017-CfP07-AIR-01-33 call on the topic “Flexible RTM tool concept for composites with spring back adjustments capabilities”. The high-level challenge that the FLEX project will be addressing is the development of the next generation RTM tooling that can be easily adjusted to account for part spring back effects. The main aim of the project will be to design an RTM tooling system that will feature decreased lead times and increased productivity. It will feature a novel distortion compensation capability based on actively changing the mould shape.

The process is driven by accurate modelling of the spring back effects thanks to the simulation of the phenomenon by analytical surrogate models. The mould will also feature automation procedures at every production step. Areas of investigation will be the preform/fibre placement, the resin injection process and mould cleaning. An advanced monitoring system will also be developed and is expected to offer unparalleled quality assurance. The technologies will be initially demonstrated on a small scale mould that will feature all complexities of a real production piece. The final tool will be built according to the specification of the Topic Manager (SAAB), verified for compliance and functionality and delivered to its premises.

Overall, FLEX aims to advance its technologies from TRL3 to TRL5 and potentially reach TRL6. Within the project, the integrated system (tooling and technologies) will be developed and validated in a relevant environment, thereby ensuring that TRL5 is achieved upon its completion. The Call requires that the demonstrator (large tool) be delivered at the Topic Manager premises, so that TR6 can be achieved post-project within the Airframe ITD.

It is envisaged that post-project development will take place across Europe with the inclusion of exploitation partners who can help take the product closer to market. To that end, the scientific knowledge developed within FLEX will be disseminated to the public, scientific communities, and end-users through established links fostered by large beneficiary partners within the consortium.
The most important technical objectives of the FLEX project were addressed as follows during the first reporting period (RP1) from Month 1 to Month 12:

* Design of a novel RTM tool with distortion compensation capabilities.
Work carried out in RP1: The sensors (Fibre Bragg Grating (FBG)) were selected and purchased by BU (WP1.4). Tests (e.g. four-point bend) were performed on them (WP2.1). Commercially available actuators and suppliers thereof were identified by LRT. ETS (WP2.3) with support from CU (WP1.5 and WP2.2) is currently developing and optimising the feedback correction system. The actuators and a versatile control system were identified by LRT (WP1.6).

* Reduce the lead time to compensate for part distortion and spring back.
Work carried out in RP1: The distortion surrogate model (WP1.5 and WP2.2) is currently being developed and optimised by CU. The material characterisation is on-going (WP1.3 led by TWI) and will provide physical data for the surrogate model. The manufacturing of test samples (WP2.6) and coupons tests (WP2.7) will start after the tool manufacture (WP2.5) is completed by LRT.

* Induce compensated mould shape through a set of external actuators that impose the correct shape based on a closed loop feedback control system.
Work carried out in RP1: The actuators were selected by LRT (supplier: Festo) and will be integrated to the tool by LRT (WP1.6 and WP2.5).

* Efficient thermal management of the tooling operation.
Work carried out in RP1: The thermal management system (WP2.3 and WP2.4) is being developed by ETS. LRT will incorporate heating elements to the tool during its manufacture in order to enable self-heating (WP2.5). On-line quality control, including fibre alignment (WP3.2) (e.g. camera monitoring and control software, developed by BU), and the tooling concepts (WP1.7) (e.g. injection strategies, developed by TWI), are led by LRT with support from TWI and BU.

* A methodology for an overall design and evaluation of the production cell.
Work carried out in RP1: The production steps were analysed by TWI, which resulted in the production of D1.1 (‘Definitions and Specifications for the Production Cell’), that identified all potential process time reductions (WP1.1) (e.g. cleaning, inspection). The tooling concepts and automation activities (WP1.2 WP1.7 and WP3.1) including a cryogenic cleaning system, are developed by LRT.
The main objective of the project is to address the distortions undergone by a composite part during its manufacture (e.g. deformation, spring-back effect), which causes it to deviate from its desired geometry. This is a common drawback in the composite part manufacture of large and complex parts. The current strategy to achieve a desired pre-defined geometry in a composite part of is very iterative. It typically consists in measuring – in the manufactured composite parts - the deviations from said geometry and incrementally optimising the tool geometry.

In the literature, most publications deal with predicting and simulating the composite spring-back, but rarely propose an applied solution to account for such phenomena. This is why in the FLEX project the implementation of the distortion correction system is being led by Loiretech in collaboration with all FLEX partners. The automation of the distortion correction is on-going, and is being refined through internal meetings, technical discussions with partners, the Topic Manager as well as suppliers. The automated distortion correction will be implemented on the final RTM tooling.

Such system would pave the way towards a streamlined and greener production process for composite parts for the aerospace industry and beyond, thereby driving the use and implementation of lighter composite parts, generating a greener and fuel-efficient fleet.
Flaperon (part to be manufactured)
Small tool (mould used to manufacture the flaperon)
Spring back effect compensation strategy on small tool