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Additive Manufacturing Optimization and Simulation Platform for repairing and re-manufacturing of aerospace components

Periodic Reporting for period 3 - AMOS (Additive Manufacturing Optimization and Simulation Platform for repairing and re-manufacturing of aerospace components)

Reporting period: 2019-02-01 to 2020-01-31

An aircraft's wings, engines and fuselage are susceptible to damage both on ground and in the air. Although scheduled maintenance checks are performed, defects can occur at any time and affect performance. Consequently, unscheduled maintenance is often needed to replace defective components and ensure safety, reliability and airworthiness. As each defect is different, unique solutions are required for each. Because engine suppliers offer 'power by the hour', they are paid only for the time that their parts are in service. Repairs need to be carried out within a limited timeframe. Components have to be assessed, repaired if necessary, then tested again and replaced within this window to avoid major disruption. Extended repair times are very expensive for engine manufacturers and it may be more cost-effective for them to replace parts early rather than repair them. Direct energy deposition (DED) systems are very flexible and show great potential for the cost-effective and efficient repair of aerospace components. They will allow damaged components to be repaired on demand, and material lost in service to be re-deposited. This will reduce repair lead times, costs and material waste, and extend the service life of damaged or worn components.
The Additive Manufacturing Optimisation and Simulation (AMOS) project had a number of objectives. To:
1. Study the process accuracy, repeatability, limitations and material integrity of a number of different DED systems using a number of materials.
2. Develop an effective system to generate the repair geometry.
3. Develop accurate models to simulate the different deposition processes.
4. Develop a repair process planning module.
5. Develop a method to optimise component design for additive repair.
6. Determine the data necessary for qualification of DED technologies for repair and remanufacture.
The project has delivered:
• A detailed set of material properties (results from tensile tests, low cycle fatigue, fatigue crack growth tests) which forms part of the aerospace qualification route
• Software and tools for repair characterisation (Canadian partners), feeding into deposition process planning
• A novel method of very accurately measuring melt-pool temperature in situ (Canadian partners) which can be used to validate process models and simulations
• Thermo-mechanical models – empirical (European partners) and simulations of melt-pool, powder-stream and part microstructure (Canadian partners)
• Process planning modules for each individual system to be used for part repair (all partners)
• Design optimisation module (European partners), which produces a set of optimised designs for objectives of performance, mechanical functionality and ease of manufacture / repair
• Evaluation of the project work for typical aerospace repairs

The European exploitable results are:
1+2. Robust parameter set and deposition parameters for Titanium powder on ECN equipment and for Inconel on USFD equipment. These results are owned by ECN and USFD respectively, who will use them in consultancy with industrial companies. After consultation, it can be exploited by companies engaged in aerospace repair or metallic component manufacture in the aerospace industry, as well as for refurbishment of castings. The expected impact is to reduce the experimental time required to determine repair parameters, and to increase confidence in the material condition of the AM material and the interface zone. This will help accelerate the take-up of AM in aerospace and in the repair market, increasing component lifetimes and reducing waste.Additional industries targeted by USFD include nuclear and oil and gas, as their deposition cell can deposit parts over 1 cubic metre.
3. Design optimisation rules for AM. This result is owned by GKN who will licence the result to their component manufacturers. As 80% of key design decisions are taken during the concept phase, it is critical to include AM-specific rules to take full advantage of its benefits during manufacture or access / material requirements during repair.
4. Modelling and design software modules for AM. This result is owned by DPS who plan to sell it as a service. It is targeted at OEMs and SMEs with AM capability; benefits include the ability to simulate distortion and to compensate. The services will be promoted by DPS through their sales force, to their clients.
5. Database of AM material properties. This result is owned by all the partners. Normalised data will be published, promoted through partner dissemination channels and shared with stakeholders such as the EU RM-platform. The target market is users of AM equipment and component designers. The database will increase confidence in the use of AM for components and for repair and will provide material data for AM-material and for the interface region. Currently, there is not a lot of ‘open’ data available; work tends to be carried out piecemeal, to different standards / protocols and to remain the property of the organisations paying for the work
6. Robotic directed energy deposition (DED) process-planning tool. This is owned by USFD and will be available within 12-18 month of the end of the project. It will be provided to companies as a service.
Progress by technical objectives and the advance beyond the state of the art are:

WP1: The standardised test protocol and the freely available material properties results will increase understanding of AM materials and interface regions, giving designers more confidence to use this material for repair / AM components (all)
WP2: advances include the benchmark test for scanning systems and the development of software for automatic defect recognition and the creation of defect geometry (Canada)
WP3: Novel thermo-mechanical models have been developed. To validate these, accurate temperature measurement is required, so a novel sapphire sensor has been developed (Canada)
WP4: DED repair desktop simulation and planning tool capable of fulfilling basic functions, including evaluation of repair requirements, recommendation of repair parameters based on AMOS materials database and generation of repair toolpath for specific repair volumes (all).
WP5: a multi-objective design optimisation system has been developed.
WP6: additional tests (low cycle fatigue and crack-growth) were carried out and results will be included with the freely available material properties. The AMOS technologies were also tested and validated.

The materials data has been obtained using standard test protocols.The AMOS results have been tested on European components (the plan to test on Canadian components is expected to occur after the end of the European part of the grant). Due to budgetary constraints, it was not possible to carry out a large validation programme, so the most challenging conditions were tested. Specific types of defect that were of interest to industrial partners were investigated. Representative specimens were repaired and tested to identify defects. The main outcome is a template outlining the specific DED operations and procedures, as well as generic considerations for the substantiation, and qualification of DED repairs. Microstructural evaluation of the failed parts has also been carried out and the data fed back to improve the process models.
AMOS Leaflet