advanCEd REar end Structural test program – low level tests

Project Information

CERES

Grant agreement ID: 864158

DOI

10.3030/864158

Project closed

EC signature date 26 September 2019

Start date 2 January 2020

End date 1 January 2023

Funded under

• SOCIETAL CHALLENGES - Smart, Green And Integrated Transport

Total cost

€ 997 595,76

EU contribution

€ 698 317,03

Coordinated by

ELEMENT MATERIAL TECHNOLOGY SEVILLE SL
Spain

Periodic Reporting for period 2 - CERES (advanCEd REar end Structural test program – low level tests)

Reporting period: 2021-07-02 to 2023-01-01

Summary of the context and overall objectives of the project

CERES aims to develop the test benches and conduct a test program for Coupons Level of the test pyramid certification approach for aeronautics. Innovative testing solutions are developed to optimize the test program. The outcomes of this project contribute to demonstrate the feasibility of novel design concepts for Large Passenger Aicraft’s Advanced Rear End (ARE). Ultimately, the validation of these new concepts supports the development of highly integrated and improved mechanical performance aircraft structure pursued by Clean Sky 2. New composite materials, advanced manufacturing procedures and repair solutions have been evaluated. Advanced monitoring techniques were implemented to achieve a deeper understanding of specimen’s behaviour and optimize testing solutions. As main conclusions of this project:
- Novel prepreg materials were mechanically characterized (TEST01). An anti-buckling device was developed to enable damage growth evaluation throughout compression after impact (CAI) tests.
- Full characterization of a thermoplastic (TP) material was achieved at coupon level in the TEST02. High-Speed Camera (HSC) and Sound-level meter measurements contributed to the failure mode evaluation.
- Mechanical evaluation of unfolding and high-load frames (TEST03) was properly achieved. Innovative testing set-up solutions developed enabled to achieve representative test boundary conditions. Digital Image Correlation (DIC) enabled the correlation with FEM predictions.
- Different repair solutions were evaluated on TP and thermoset (TS) at coupon level (TEST04). Laser displacement sensor enabled to obtain actual data on displacement level. Exhaustive characterization of Complementary LRI coupons on different laminates was properly completed.
- The evaluation of the mechanical behaviour and repair performance of TP and TS stringer specimens by means of crippling tests (TEST05) was carried out.
- The residual strength of plain specimens under compression loads after impact (TEST06) was successfully evaluated. It was proved that the anti-buckling device developed in the TEST01 avoided undesirable failure modes. The results were published in the MATCOMP21.
- lntact strength and damage tolerance were evaluated for several multispar configurations (TEST07). Low-cost materials were evaluated and compared to the current baseline material. HSC and sound-level meter enabled to study the failure mode of the T-Joint specimens.
- The mechanical behaviour of TS and TP stringer run-out (SRO) details was successfully assessed (TEST08). Static and fatigue loading were applied at room temperature (RT) and after Hot-Wet (HW) ageing. Additionally, DIC supported the evaluation of strain field on some specimens.

CERES aims to faster validation capacity of cutting-edge design solutions in Europe by addressing the Aircraft Factory of the Future needs, and will impact society by increasing the technological knowledge and background of the companies involved in the Aircraft Manufacturing Value Chain and encouraging more skilled jobs.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

CERES Project has been successfully completed. All the main objectives were accomplished:
TEST01 covered the mechanical characterization of novel prepreg coupons at RT and HW, manufactured by ELEMENT. These tests were executed in the first reporting period (RP1) and results were reported in deliverable D1.1.
In TEST02 the mechanical properties of a TP material (tension, compression, filled hole tension, CAI…) were assessed, including the use of HSC. These tests were executed in the RP1 and results reported in deliverable D2.1.
TEST03 comprised the execution of unfolding tests and static tests on high load frames under representative boundary conditions. These tests were performed in the second reporting period (RP2), and results reported in deliverable D3.1.
In TEST04, several repair solutions and laminates were evaluated for TS and TP composites, including the assessment of ageing. Complementary tests were performed on TP coupons. These tests were completed in RP2, and results included in deliverable D4.1.
TEST05. The work performed in TEST04 was upscaled. The mechanical behaviour of repair technologies was assessed by means of compression tests on aged TS and TP T-stringer specimens. These tests were completed in the RP2 and results reported in deliverable D5.1.
TEST06. CAI performance of different laminates was evaluated. ELEMENT developed a new impact tower for low-energy impacts (BVID). These tests were completed in the RP2 and results included in deliverable D6.1.
TEST07 covered the mechanical characterization of T-Joint specimens, evaluating different composite materials and thickness. These tests were completed in the RP2 and results reported in deliverable D7.1.
TEST08 was the last stage of repair technologies validation initiated in TEST04. TP and TS SRO specimens including repairs were subjected to static and fatigue tension tests. These tests were executed in the RP2 and results reported in deliverable D8.1.
The results of this Project have been disseminated through different channels, such as the Project website. ELEMENT participated in the NEWFRAC Workshop, where the progress on CERES Project was presented. ELEMENT also participated in the National Congress on Composite Materials (MATCOMP21), where a banner of ELEMENT stand was dedicated to CERES and three publications related to the Project were presented.
The work performed on advanced monitoring techniques in this Project, especially on DIC, has been attractive for the Topic Manager and AERNNOVA. Thus, this way of testing strain monitoring will be further investigated.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

CERES has performed a development in advanced experimental testing methodologies and innovative techniques that are applied to improve the accuracy of test results, reduce the number of test specimens, and reduce testing lead times. The execution of CERES matches the expected impacts set out detailed in the CS2 Work Plan:
CERES contributes to the reduction of CO2 emissions by contributing to the development of a new light weight rear end. Saving weight by replacing heavy materials with lighter ones with similar mechanical capabilities is a strategy to achieve innovation, especially in commercial aircraft. Lighter aircraft means less combustible, which means less cost for the airlines and the passengers.
CERES brings technical impact through the development of innovative test rigs for the validation of design concepts, materials and processes which will be implemented in the ARE. The application of advanced monitoring techniques contributes to the consolidation of these technologies.
CERES drives a new solution of testing methodologies that is aimed to optimize the costs of a test campaign for the validation of novel design concepts to be implemented in ARE. The result of the “Advanced Engine Integration Driven Fuselage” demonstration will deliver a key enabler to acquire 15-20% fuel saving potential in combination with the capabilities to produce a competitive industrial solution for a short and medium haul next generation large passenger aircraft.
The benefits from CERES’s outcomes contribute to bring the opportunity to the European Aerospace industry to reverse the deindustrialization of Europe and face important societal problems related to high rates of unemployment.

Overview of validation technologies application to demonstrate new structural developments