Advanced Bearing Technologies to Increase Capabilities

Project Information

ARCTIC

Grant agreement ID: 686366

DOI

10.3030/686366

Project closed

EC signature date 21 December 2015

Start date 1 January 2016

End date 30 June 2022

Funded under

• SOCIETAL CHALLENGES - Smart, Green And Integrated Transport

Total cost

€ 2 388 531,25

EU contribution

€ 2 388 530,50

Coordinated by

SKF AEROSPACE FRANCE
France

Periodic Reporting for period 4 - ARCTIC (Advanced Bearing Technologies to Increase Capabilities)

Reporting period: 2020-07-01 to 2022-06-30

Summary of the context and overall objectives of the project

The development of VHBR engines is a promising engine concept to fulfill the objectives of the Cleansky 2 programme. The significant environmental benefits of this new engine are synonymous with an increased speed and rolling contact stress capabilities.
In terms of engine performance, the design, sizing and capacities of the rolling element bearings can affect the whole engine architecture. The rolling element bearings have been clearly identified as crucial components with respect to reliability.
Nowadays, new engine architecture developments are possible only if they take into account new technologies and developments for engine’s component parts.
The main scope of ARCTIC proposal is thus: “to develop and demonstrate various unique rolling bearing technologies that overcome current design rules of aero-engine bearings and allow the development of a VHBR engine (or other high-performance architectures)”.

ARCTIC is full in line with the Clean Sky 2 program, since it supports the key Societal Challenge. It enables cutting edge bearing solutions for further gains in decreasing fuel burn, CO2, NOX, noise emissions. ARCTIC proposers are committed to support future global leadership of the European aeronautical industry supply chain, creating jobs through and reinforced competitiveness.

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

The concept of an ideal SKF aero-engine bearing steel was developed in order to translate the VHBR aero-engine application conditions into the metallurgical requirements for the steel rings for the hybrid bearings.

For the VIM-VAR route, a new patented novel composition (ARCTIC15 steel) have been designed and produced using an industrial 16-ton VIM/VAR melt. The development of a low pressure carburizing heat-treatment for the ARCTIC15 has been conducted with university and supplier partnerships to reach the economic and technical targets. The complete metallurgical and physical characterization of the ARCTIC15 has then been performed.

For the PM steel technology evaluation, the AMS6560 has been selected based on first elementary rolling contact tests as the best solution for through hardened high temperature PM steel. Regarding to the case-hardened PM steel, it has been decided to base the approach on the same composition than the novel ARCTIC15 alloy, applying to the VIM-VAR melt ingot an atomization, then a HIPed process. The result (PM-HIPed ARCTIC30 steel) has been also metallurgically characterized to confirm a good microstructure integrity.

The validation of the steel developments, couple with the introduction of ceramic rolling elements (=advanced hybrid bearing) has been performed by a multi-scale back-to-back demonstration of +15% (for conventional route steel) up to +30% (for powder metallurgical steel) in loading capacities compared to current aero-engine steel solutions (i.e. M50NiL rings + M50 balls). These increases of performance have been demonstrated in nominal running conditions but also in degraded running conditions (poor lubrication, polluted oil, high temperature, etc...).

On a general overview on the results from elementary to full-scale tests, the new bearing technologies (ARCTIC15 steel, PM AMS6560 and ceramic rolling elements) have over-performed the baseline bearings, even if running at higher loads.

Additional tasks have been run to convert the testing results into design rules and manufacturing parameters usable by the bearing design office and the manufacturing teams.

Coupling the results of a semi-analytical contact model and some experimental characterization of the studied steels, an evaluation of the rolling contact fatigue endurance limits has been made for aerospace application temperatures. The estimation seems aligned with the legacy design rules for the M50NiL. These endurance limits are clearly increased for the ARCTIC15 and for the AMS6560 reaching the initial project targets

After 6.5 years of development activities, the ARCTIC project has achieved its objectives.

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)

The main impact of this proposal is to provide key bearing steel, heat treatment and raceway finishing technologies for the development of a VHBR engine and other next generation engines to meet the objectives of the Clean Sky 2 programme in terms of environmental benefits and European competitiveness.
The technical impacts of ARCTIC project are potentially huge and because several major advances/innovations will be necessary to achieve the technological step requested.

- The possibility offered by the project technologies to design new environmentally friendly aero-engines.
- A full exploitation of components potential in terms of performance (a totally leakage free, power and weight optimized solution) and life estimation through increased knowledge of the material fatigue behaviour.

The envisaged technical exploitation of the results is significant as there will be:
a) Direct exploitation of cutting edge rolling bearing technologies: newly developed materials (steels & ceramics) and associated surfaces treatments,
b) A breakthrough in terms of rolling bearing performance and design possibilities,
c) Additional exploitation of some stand-alone results: experimental database results and back-to-back comparison of PM-HIPed steel with conventional remelt steel technology; application of state-of-the-art mechanical contact modelling,

It is also important to note that the developed technologies in this project (material and surface engineering development) can be directly transferred, like elementary bricks, to improve performances of other engine technologies (for example gears) or in other sectors (i.e railway\automotive\maritime).

Employment will be directly linked to the economic impact of ARCTIC project at the European and global levels. ARCTIC project will maintain and create jobs for aero-engine manufacturers and also for rolling bearing and material suppliers.
Employment of highly skilled personnel is required for some of the proposed technologies.
ARCTIC project has promoted education by involving a university/research centre.

The next steps of those development activities run during the ARCTIC project will be to finalize the industrialization of those technologies targeting future engines applications. New industrial melts of ARCTIC15 steel will be produced and aerospace application rolling bearings will be produced and tested on demonstrators.

Surface hardness of case-carburized ARCTIC15 vs M50NiL as function of the temperature.

Composition of the industrial VIM/VAR Arctic 15 melt (composition values in wt%)

Hardness profile of the carburized ARCTIC15 steel in comparison to M50NiL.