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improved Method to Analyze composite materials suiTable for SLP structures with the aim of Reducing the Impact on the required eXperimental testing campaign

Periodic Reporting for period 2 - MATRIX (improved Method to Analyze composite materials suiTable for SLP structures with the aim of Reducing the Impact on the required eXperimental testing campaign)

Période du rapport: 2020-04-01 au 2021-12-31

MATRIX is a project funded by the Clean Sky 2 Joint Undertaking under the European Union’s Horizon 2020 research and innovation program.

MATRIX intends to address the economic challenge posed by the airworthiness certification for composite SLP structures in FAR 25, by developing an OPTIMIZED approach to analyze, test and validate a large number of innovative materials suitable for HECOLAG purpose.
HECOLAG (High Efficiency Composites LAnding Gear) is a Clean Sky 2 Systems ITD (Integrated Technology Demonstrator) project aimed at developing highly efficient composite landing gear parts, both for large aircraft nose landing gears and helicopter landing gears.

MATRIX innovation is to compute both type and variability of the defects that arise during manufacturing processes and substantially improve the accuracy of the allowables predicted by standard numerical method.
More than 130 defect types and more than 60 sources of variability and uncertainty can be identified for the resin transfer molding processes. Many of these sources of variability have their roots in the reinforcements used and in the ways that those reinforcements map to the geometry of components. Understanding the underlying causes for variability of reinforcements and their deformation and consolidation characteristics is one key to the understanding of variability in product performance.

MATRIX main goals are:
• to demonstrate the feasibility of virtual mechanical testing of composites in the near future, starting from CFRP Textile preforms and RTM materials suitable for HECOLAG consortia
• to improved single load path material qualification method by reducing the lead-time and cost associated to material qualification for single load path structures and allow for more design flexibility, thanks to the above innovative software platform
• to test, following the building block approach, single load path structure representative of a Landing Gear axle.
• To make available to TM and partners the validated and matured “smart tool” suitable for further development across the project schedule.

The results achieved within MATRIX allowed to draw the following conclusions:
• The methodological workflow ideated and implemented in MATRIX proved to be globally adequate to improve the test matrix for new composite material certification campaign, with room for improvement with regards to the robustness and the capability to include (a) NDI test results and (b) properly map defects and variations of properties resulting after manufacturing into the FEA model
• The MATRIX numerical tool proved to be a valid tool to generate a set of statistically representative candidate materials that match the global behavior observed through experimental testing
• The obtained results suggests that limiting the statistical analysis to the basic material properties (in terms of resin and reinforcement properties) can result in unreliable results when the aim is to (a) propagate this variability to L2 / L3 test levels and (b) assess the uncertainty of the numerical predictions at these higher levels.
• The recommendation for future work is therefore that the statistical analysis should focus on the variability of the factors linked to manufacturing processes, which are presumably the most important to determine the variability of the L2 / L3 finite element models
The activities of the consortium have focused on the following main aspects:

• Material choice
• Material test plan
• Improved method definition
• Design, manufacturing and testing of L2/L3 samples
• Numerical testing of L1, L2, and L3 samples and correlation of numerical / experimental results

The key project results consist on:
• A methodological workflow describing necessary requirements, tasks and dependencies to calibrate material models based on test data at different levels (L1/L2)
• A set of executable workflows providing interoperable numerical tools, templates, and algorithms allowing to execute the proposed improved method
• A large set of test data results produced during the experimental campaign, available for further analyses and processing
• A demo environment, accessible via a cloud machine upon request by the TM and with a subset of the employed tools (no 3rd party software), workflow templates, algorithms and models

These results are being exploited by the project partners as follows:
• For academic partners:
• strengthening of the positioning as experts in the field of advanced design of composite aerostructures
• For Independent Software Vendors:
• Know-how in material modelling optimization, with new demonstrators and use cases
• New algorithms and interfaces towards 3rd party tools (MSC Digimat®)
• For Industrial end-users:
• New approach for design and development of products based on composite
• Design lead-time reduction
MATRIX activities have been focused on the introduction of a lightweight and cost effective composite primary structural part. The state-of-the-art consists on performing a large number (thousands) of material tests at L1 while MATRIX will reduce of one order of magnitude the number of tests by improving a validated virtual testing campaign.
Moreover, MATRIX have incepted an approach to reduce the number of physical tests at L2 and L3 through development of a method aimed at propagating the material properties calibrated during the L1 virtual testing campaign and coupling these with information related to the manufacturing process.
The expected impact of the MATRIX project is mainly associated with the possibility to reduce the amounts of physical testing that are needed in order to design and validate advanced materials for aerospace applications.
The expected impact is therefore two-fold:
- Economic impact: the improved method defined in MATRIX can result in significant savings of material and energy due to the less amount of required physical testing
- Technological impact: the improved method, strongly based on numerical design approaches (opposed to labour-intensive, physical testing approaches) reduces manual (error-prone) operations and can be highly automated, bringing competitiveness thanks to the enhanced scalability of these approaches and the reduction of design lead-time, above for new enhanced composite material with specific internal structure
MATRIX - logical framework