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Evaluation of LAminate composite Distortion by an Integrated Numerical-Experimental approach

Periodic Reporting for period 2 - ELADINE (Evaluation of LAminate composite Distortion by an Integrated Numerical-Experimental approach)

Reporting period: 2021-03-01 to 2022-02-28

ELADINE aims to implement a numerical tool that can reduce the recurring costs of low-volume composite manufacturing of airframe parts thus reducing of the overall manufacturing effort and carbon emissions through three converging manners:
1. The design and geometry compensation of the tooling itself as an essentially integrated phase of the manufacturing cycle. ELADINE focuses specifically on composite tooling and the combined behavior of tools and parts during the curing process;
2. Mastering the control of the manufacturing process in order for large aero-structures and their assemblies not to fail the tolerance constraints;
3. Optimizing the number of coupons and specimen testing before manufacturing of aero-structures, by a thorough understanding of thermal, chemical and mechanical behavior of tooling and parts, tool-part interaction and resin flow.
The main outcome of ELADINE project is the development of a cost-competitive method for the analysis and simulation of the spring-in phenomena for integral structures based on detailed design information, materials properties and process definition.
4. The numerical simulation tool has been scaled to a full size aircraft wing. The simulation takes into account a full scale complex tooling geometry and the geometry of the part.
The list of objectives:
- understand the causes of spring-in during the manufacturing process;
- identify, define, understand, simulate and validate the critical parameters;
- verification of the resulting numerical approach by small specimens using both prepreg and LRI coupons;
- develop and implement a promising methodology for detecting the spring-in phenomenon;
- provide a numerical model approach to simulate and guidelines to help alleviated the spring-in phenomenon;
- robust and reliable numerical simulation tool to support concept and design phases of tooling and composite parts.
WP1 - Numerical simulation approach definition
This WP considered the alignment of the consortium to the Topic leader requirements for manufacturing the 7 meter composite OPTICOMS wing.
A trade-off study was performed for the numerical model in order to decide on the most suitable approach for the simulation strategy of the complex 7 meter composite structure
The complex program for manufacturing coupons, process monitoring and data analysis was defined.
The design of the coupons tools was completed.

WP2 - Test coupons manufacturing and process monitoring
The extensive experimental program on curved panel and C-shaped coupons was carried out in order to feed the numerical model calibration process with the essential experimental data.
The dominant factors which influenced the spring-in phenomenon were investigated experimentally.
The experimental monitoring procedures for the coupons reached good maturity. The data interpretation process has reached good maturity.
The 1st phase of the numerical tool development and the calibration were completed with very good results.

WP3 – Numerical model validation
The validation workflow was defined:
(1)the manufacturing process of the demonstrator was LRI (Liquid Resin Infusion);
(2)process monitoring with Fiber Bragg Grating (FBG) and Dielectric Current(DC) sensors;
(3)a mini-demo would be manufactured before the final downscale demonstrator aiming to test sensor’s embedding in a more complex geometry;
(4)the map of the network of sensors for the downscale demonstrator was developed based on the results of the midi-demo test, and
(5)the guidelines for embedding the sensors were outlined.
In the calibration of the simulation tool, the first step in the analysis of the 1.2m demonstrator spring-in was the inspection of the CAD file to define a modelling approach that will be reliable in the curing simulation. Several approaches were defined and tested numerically in order to evaluate the most promising results.
WP3 remarkable achievements:
•Complex composite structure sensors mapping for curing process monitoring with sensors of the manufacturing process
•Spring-in simulation of a real aero-structure manufacturing process.

WP4 – OPTICOMS wing numerical analysis of distortion
The mature numerical tool was employed to simulate the manufacturing process of the 7m wing including all the tooling and auxiliaries.
The biggest achievement of this task means the completing of the effort of ELADINE in a successful manner. The numerical tool is capable of offering a complete process simulation for both LRI and prepreg.
Main achievements of ELADINE:
- A robust methodology for composites manufacturing process monitoring in order to provide essential data for the numerical simulations calibration;
- A functional simulation tool of composites manufacturing, capable of evaluating spring-in for large scale aerostructures.
Disemination actions:
•The High Performance Composites Workshop “AEROSPATIAL 2020”, 15-16 October 2020, Bucharest, Romania,
•11th EASN Virtual Conference on “Innovation in Aviation & Space to the Satisfaction of the European Citizens”
•project website

Exploitation of results:
The prime beneficiary of ELADINE is IAI in the OPTICOMS program. The simulations and experimental results were the key components in the FITCoW tooling assembly compensation strategy.
On a larger scale, the numerical model will be capable to accurately predict the manufacturing deformations that composite parts develop throughout the curing cycle. Its applicability is limited, for the time being, to components such as wing skins and spars or different combinations of such geometries.
ELADINE developed a numerical tool capable of accurately predicting spring-in on complex aero-structures, compatible with two composite-manufacturing methods.
We have a strong belief ELADINE is progressing beyond state of the art because of approaching the numerical simulation strongly supported on the extended experimental process monitoring. The simulations are done on complex geometries: skin & stringers/stiffeners configuration. The numerical tool is being calibrated using experimental data to correlate the numerical analysis and to replicate a very complex behavior both in terms of accuracy and precision.
As impact, following the ELADINE compensation strategy the drop in rejected parts due to tolerancing issues will be significant .
The impact of ELADINE's results on Aerospace and non-Aerospace:
•A validated and reliable composites distortion software tool;
•Decreased cost and environmental impact through precise control of LRI process;
•Adequate design rules & guidelines for composites tolling and composite parts;
•Thorough curing process understanding and the macro-scale effect allows for fine tuning of the manufacturing process;
•Develop guidelines and design principles applicable to the non-aerospace industry sector (automotive, energy, tooling manufacturing, etc.)
•Make substantial progress in the reduction of the environmental impact of the manufacture, maintenance and disposal of aircraft and their related products
Skills gained by the ELADINE consortium members:
•Designing and manufacturing aero-structures components with high tolerances requirements;
•Foreseeing and managing otherwise-inevitable deformations;
•Enabling co-polymerization and thus, precision manufacturing of large components;
•Understanding and managing CTE-related phenomena on a very fine scale;