Periodic Reporting for period 2 - RETPAIR (REsearch on ThermoPlastic repAIRs)
Reporting period: 2022-07-01 to 2023-09-30
The main objective of RETPAIR is the development of new high performance, flexible and cost-effective, automated, and robotized net-shape technologies to rework and repair TPC parts to be integrated in the manufacturing line. The proposed solutions assure one-side accessibility and are supported by a digital-based methodology to assist the patch design and manufacturing.
Three different solutions, divided in two streams, were developed:
a) Induction welding repair solution for structural applications: a pre-manufactured patch (or hard patch) is welded to the parent structure, based on a flexible, adaptable to different patch geometry and size, high-speed induction heating device, avoiding the use of metallic inserts into the joint. In this sense, a new approach based on co-consolidation strategies was applied effectively, repairing the damage without pre-patch consolidation, using a metal sheet to create externally the heat and melt the layers by heat conduction, consolidating the patch directly on the damage.
b) In-situ consolidation Automated Manufacturing based solutions for structural and non-structural applications based on automated and robotized layer-by-layer patch in-situ creation. Two different technologies were developed:
b.1) Automated laying (AL) solution based on Automated Fiber Placement (AFP) technologies (automated tape laying/automated fibre placement).
b.2) 3D printing based on Fused Filament Fabrication (FFF) solution, using both continuous carbon fibre filament (cCF-filament) and polymer filament, allowing tuned strength of the patches for different repair requirements, from structural to non-structural repairs.
To assure repair quality, the critical process parameters were monitored, controlled and finally optimized using advanced digital tools and based on the thermal and mechanical resulting properties. Besides, a FEM simulation methodology of the structural behavior of the repairs was developed.
Three different solutions, divided in two streams, were developed:
a) Induction welding repair solution for structural applications: a pre-manufactured patch (or hard patch) is welded to the parent structure, based on a flexible, adaptable to different patch geometry and size, high-speed induction heating device, avoiding the use of metallic inserts into the joint. In this sense, a new approach based on co-consolidation strategies was applied effectively, repairing the damage without pre-patch consolidation, using a metal sheet to create externally the heat and melt the layers by heat conduction, consolidating the patch directly on the damage.
b) In-situ consolidation Automated Manufacturing based solutions for structural and non-structural applications based on automated and robotized layer-by-layer patch in-situ creation. Two different technologies were developed:
b.1) Automated laying (AL) solution based on Automated Fiber Placement (AFP) technologies (automated tape laying/automated fibre placement).
b.2) 3D printing based on Fused Filament Fabrication (FFF) solution, using both continuous carbon fibre filament (cCF-filament) and polymer filament, allowing tuned strength of the patches for different repair requirements, from structural to non-structural repairs.
To assure repair quality, the critical process parameters were monitored, controlled and finally optimized using advanced digital tools and based on the thermal and mechanical resulting properties. Besides, a FEM simulation methodology of the structural behavior of the repairs was developed.
The first main goal achieved was the development of structural repair solution based on hard-patch welding. A new concept based on co-consolidation strategy was developed, using a flexible induction blanket to heat the part and consolidate the patch directly on the damage to be repaired. Consolidating the plies to create the patch at the same time that the joint to the part to be repaired is created, doing both activities at the same time, since temperatures above melting temperatures are achieved through all the plies and on the interface with the damaged part.
Other of the main challenge covered by RETPAIR was developed an automated FFF-based solution for in-situ repair patch manufacturing for small-medium size repairs, and AFP based solution for big repairs. Appling an automated manufacturing strategy to build the repair directly above the damage, using a ply-by ply an approach in situ repair in both scenarios. Both technologies were proved and a processes windows were studied in both cases to determine the optimum process parameters to be used for a further mechanical test campaign, that feed Finite Element Models to assess repair process.
To define the specific requirements for in-production-repair, establishing the repair applications scenarios for setting the study cases. Based on this, a screening was carried out in order to select the technology for hard patch and for in-situ repair patch application to be investigated in WP3. In addition to which, it was carried out a selection and study cases design for the different repair scenarios.
Through this period, it was also developed the digital based patch repair design methodology. For this, it was required to design the data acquisition, point cloud generation and CAD model building, after that it was needed to develop the patch design based on the digitalised damage. AIMEN provided the input for CT activities, which was scanned damaged surfaces (point clouds). CT has developed a set of automatizations that allows the recognition of the type of damaged, and the generation of the 3D models and Ply-by-Ply models of the repair patch manufactured.
Repair solutions were validated determining the mechanical performances and thermal properties for the different study cases. For each repair technology the process window was study and optimum process conditions were defined. Defining set up configuration that allows to carry out repairs on a scarf stepped surface to be repaired, as it is needed in RETPAIR project. All the technologies were validated at a representative level, and 3D environment simulations were studied on the Multi-Functional Fuselage Demonstrator to determine its reparability with RETPAIR technologies. Furthermore, a road map until TRL 6 was defined to scale up the technologies to a industrialization level.
During the second period of the project, several interventions have been carried out in conferences and fairs to disseminate the results.
Oral Presentations: - ECCM20. - 12TH EASN; - 13TH EASN
Poster on congress: MFFD Stakeholder Event 2023.
Participation on workshops: - Recycling in Aviation. Clean Aviation Workshop; - 13TH EASN
Fairs: - ITHEC22; - JEC WORLD. 2022 and 2023
Scientific publications: - ECCM20. 20th ; ICCM2023
A dedicated project website was created for the RETPAIR project (http://www.retpairproject.eu/(opens in new window)).
Other of the main challenge covered by RETPAIR was developed an automated FFF-based solution for in-situ repair patch manufacturing for small-medium size repairs, and AFP based solution for big repairs. Appling an automated manufacturing strategy to build the repair directly above the damage, using a ply-by ply an approach in situ repair in both scenarios. Both technologies were proved and a processes windows were studied in both cases to determine the optimum process parameters to be used for a further mechanical test campaign, that feed Finite Element Models to assess repair process.
To define the specific requirements for in-production-repair, establishing the repair applications scenarios for setting the study cases. Based on this, a screening was carried out in order to select the technology for hard patch and for in-situ repair patch application to be investigated in WP3. In addition to which, it was carried out a selection and study cases design for the different repair scenarios.
Through this period, it was also developed the digital based patch repair design methodology. For this, it was required to design the data acquisition, point cloud generation and CAD model building, after that it was needed to develop the patch design based on the digitalised damage. AIMEN provided the input for CT activities, which was scanned damaged surfaces (point clouds). CT has developed a set of automatizations that allows the recognition of the type of damaged, and the generation of the 3D models and Ply-by-Ply models of the repair patch manufactured.
Repair solutions were validated determining the mechanical performances and thermal properties for the different study cases. For each repair technology the process window was study and optimum process conditions were defined. Defining set up configuration that allows to carry out repairs on a scarf stepped surface to be repaired, as it is needed in RETPAIR project. All the technologies were validated at a representative level, and 3D environment simulations were studied on the Multi-Functional Fuselage Demonstrator to determine its reparability with RETPAIR technologies. Furthermore, a road map until TRL 6 was defined to scale up the technologies to a industrialization level.
During the second period of the project, several interventions have been carried out in conferences and fairs to disseminate the results.
Oral Presentations: - ECCM20. - 12TH EASN; - 13TH EASN
Poster on congress: MFFD Stakeholder Event 2023.
Participation on workshops: - Recycling in Aviation. Clean Aviation Workshop; - 13TH EASN
Fairs: - ITHEC22; - JEC WORLD. 2022 and 2023
Scientific publications: - ECCM20. 20th ; ICCM2023
A dedicated project website was created for the RETPAIR project (http://www.retpairproject.eu/(opens in new window)).
The main objective of RETPAIR is the development of new high performance, flexible and cost-effective, automated and robotized technologies to rework and repair thermoplastic composite parts, to be integrated in the manufacturing line. The combined use of different digital tools will allow a time reduction of 15% in patch design and an accuracy improvement compared with conventional design procedures. Right now, after RETPAIR project ends it can be confirmed, since these objectives were achieved and a new strategy to carry out thermoplastic repairs was proved satisfactory.
For the development of the one of the main objectives is the welding time reduction, 70% lower than the conventional repair procedure. Trying to achieve hard-patch welding, based on the induction welding or co-consolidation approach, a target joint strength close to the 90% of the parent material, based on a flexible induction welding solution, and with a important time reduction.
Related with the develop an automated laying based on AFP solution, and FFF-based repair solution for in-situ patch creation, for structural and non-structural repair, using a continuous carbon fibre and short carbon fibre, to accomplish the structural and non-structural requirements, respectively. Compared with the conventional repair method, the repair time was reduced, ensuring the minimal mechanical strength required, defined for the different technologies and scenarios.
So that, RETPAIR developments resulted in flexible and accurate repair technologies for high performance and quality solutions, thus collaborating in TPCs growing use in the aeronautic industry.
RETPAIR project will ensure a strong strategic impact and will have clear Socio- Economic benefits within the next five to ten years by contributing to:
• Enhance European aeronautic industry competitiveness.
• Enhance European employment.
• Improvement of the quality of life: using a new process with clearly health and environmental benefits
• Develop new solutions and technologies that can create an economic impact in RETPAIR partners.
For the development of the one of the main objectives is the welding time reduction, 70% lower than the conventional repair procedure. Trying to achieve hard-patch welding, based on the induction welding or co-consolidation approach, a target joint strength close to the 90% of the parent material, based on a flexible induction welding solution, and with a important time reduction.
Related with the develop an automated laying based on AFP solution, and FFF-based repair solution for in-situ patch creation, for structural and non-structural repair, using a continuous carbon fibre and short carbon fibre, to accomplish the structural and non-structural requirements, respectively. Compared with the conventional repair method, the repair time was reduced, ensuring the minimal mechanical strength required, defined for the different technologies and scenarios.
So that, RETPAIR developments resulted in flexible and accurate repair technologies for high performance and quality solutions, thus collaborating in TPCs growing use in the aeronautic industry.
RETPAIR project will ensure a strong strategic impact and will have clear Socio- Economic benefits within the next five to ten years by contributing to:
• Enhance European aeronautic industry competitiveness.
• Enhance European employment.
• Improvement of the quality of life: using a new process with clearly health and environmental benefits
• Develop new solutions and technologies that can create an economic impact in RETPAIR partners.