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High load gear and bearings materials

Periodic Reporting for period 4 - HILOGEAR (High load gear and bearings materials)

Período documentado: 2021-05-01 hasta 2022-11-30

The HILOGEAR project supports the aims to mature differentiating technologies and processes that could be introduced in the innovative drive system module for the UHPE (Ultra High Propulsion Efficiency Engine) demonstrator.
The Ultra High Bypass Ratio technology achieved with the geared turbofan concept, that decouples fan and turbine speeds by means of an Integral Drive System (IDS), is an innovative architecture that can enable significant reduction in fuel burn, noise and emissions.

Since classical aerospace materials, although performant, do not exhibit all the necessary technical characteristics to fulfil both bearings and gears strength needs for their application in the UHPE power gearbox, innovative materials and heat treatments have been investigated.

In order to enable the introduction of such innovative materials/heat treatments in the UHPE power gearbox an extensive experimental activity was required aimed to verify the performances of bearings and gears in operating conditions representative of those on the new engines (i.e. high load and high temperature).

The project HILOGEAR is structured in a management and dissemination work package and in four main technical work packages aimed to:
-select the most promising steel materials and related surface treatments for their application on bearings and gears
-design the test articles (i.e. the samples gears and bearings) and the test rigs required for the tests execution
-identify optimal test plans to achieve robust and reliable results minimizing the testing time and the number of test articles
-procure the test articles and the test rigs
-execute a complete characterization of the gears and bearings performances, even at very high temperature (up to 200°C and for bearings in contaminated conditions).
The main achieved results are:
- Selection of the most promising materials/heat treatments to characterize by means of tests on gears and bearings
- Test articles gear design (i.e. gears for tests on STBF rig and power circulating rig)
- Bearing design for tests on bearings
- STBF hot oil test rig design, procurement and commissioning
- High torque power circulating rig design, procurement and commissioning
- Modification of existing bearing test rig L17 for hot oil condition, procurement and commissioning
- Test plans definition for tests on gears and bearings
- Gear specimen manufacturing for different materials/processes materials
- Bearing specimens manufacturing for different materials/processes materials
- Execution of bending tests (both on STBF rig and power circulating rig), even at very high cycle (i.e. up to 99 millions) and scuffing tests on carburized gears and "green nirided" gears
- Execution of tests on bearings for the carburized version and dupex hardened version.

The results in terms of bending strength obtained in the SBTF and power circulating rig tests for the carburized material were compared with the one obtained for a baseline material hugely used by the Topic Manager for aerospace applications. The improvement was considerable high and the results enable the possible use of this material for future applications.
The results in terms of scuffing resistances are aligned to the expectations both for the carburized and the “green nitrided” materials.
Global results obtained on the carburized version are very satisfying, both for gears and bearings, and showed a relevant improvement with respect to the baseline carburized materials.
The results obtained on bearings allowed the identification of points of improvement for the future perfectioning of the duplex hardened recipe and showed performances for the carburized version higher than expected.
The duplex hardened recipe can be perfectioned in future projects.

The following positive main impacts can be listed:
- Development and perfectioning of methodologies to experimentally characterize performances of innovative materials and heat treatments for bearings and gears, improving the technical expertise;
- Reinforcement of experimental equipment (enlarged performances of STBF rig, power circulating rig at AM Testing premises and L17 rig at FAG premises);
- Introduction of innovative materials and heat treatments that can lead to significant reduction in fuel burn, noise and emissions for future aeronautical engine applications;
- Opportunity for AM Testing, that is a small-medium enterprise, to collaborate with a big company as FAG to develop innovative technologies in aeronautical field;
- Increase in employment for AM testing;
- Strengthened relationship with the Topc msnager (Avio Aero) for launching future collaborations.
The project HILOGEAR responds to the main requirement regarding gearbox system optimization for bearing integration and associated components such as gears.
The main objective was to demonstrate new and innovative technologies that could be introduced in the innovative drive system module for the UHPE (Ultra High Propulsion Efficiency Engine) demonstrator.
The project could have an economic impact on the European industry by:
-reducing engine fuel consumption
-increasing safety
-reducing engine emissions
-improving propulsive efficiency
-reducing operating costs
-increasing the competitiveness of the European aviation industry.

Furthermore, carrying out the research project at a European level, with know-how and experiences being shared, will contribute to the growth and competitiveness of the industry.
The project had an impact on the Consortium by consolidating the role of both the Partners in the field of experimental research on bearings and gears for advanced applications; the project, in continuity to other already started research activities in the same field, allowed to strengthen existing know-how and to further confirm the excellence of Partners in this area of study, giving the opportunity to reinforce the collaboration between FAG Aerospace and AM Testing in this field of research.
Methodologies to experimentally characterize performances of innovative materials and heat treatments for bearings and gears, improving the technical expertise have been developed and perfectioned.

Introduction of innovative materials and heat treatments can lead to significant reduction in fuel burn, noise and emissions for future aeronautical engine applications.
The results in terms of bending strength obtained in the SBTF and Power circulating rig tests for the carburized material were compared with the one obtained for a baseline material hugely used by the Topic Manager for aerospace applications.
The improvement was considerable high (+10%) and the results enable the possible use of this material for future applications.

HILOGEAR contributed to strengthen the relationship with Avio Aero for launching future collaborations: AM Testing is involved in "OFELIA" and "AMBER" projects in the framework of Clean Aviation.
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