MatCH4Turbo · Project

Predicting When Aircraft Engine Gears Will Fail Before They Actually Break

transportTestedTRL 4Thin data (2/5)

Gears inside aircraft engines spin at extreme speeds and must survive billions of stress cycles without cracking. Think of bending a paperclip back and forth — eventually it snaps, but predicting exactly when is surprisingly hard, especially for new types of steel. This project built a specialized high-speed test rig and developed computer models that can calculate exactly how long next-generation case-hardened steel gears will last under these punishing conditions. The result is a way to design safer, lighter gears for the fuel-efficient jet engines of the future.

By the numbers

EUR 2,365,530

EU contribution for VHCF gear material research

New case-hardening steel developments characterized

Research partners in the consortium

Total project deliverables

Demo deliverable — recirculating gear test rig built and validated

The business problem

What needed solving

Aircraft engines are moving toward Ultra-High Bypass Ratio designs that demand lighter, faster-spinning epicyclic gearboxes. Current fatigue prediction methods do not reliably cover the Very High Cycle Fatigue regime these gears operate in, meaning engineers cannot confidently predict when new case-hardened steel gears will fail. This creates a certification bottleneck: without accurate lifetime predictions, manufacturers must over-engineer components or run expensive, time-consuming physical tests.

The solution

What was built

The project delivered a high-power recirculating gear test rig (assembled, commissioned, and performance-validated), VHCF material data for two new case-hardening steel grades, and a validated FE-based material life model using weakest link analysis conforming to ISO 6336 standards.

Audience

Who needs this

Aircraft engine OEMs designing next-generation power gearboxesAerospace gear and transmission suppliersSpecialty steel producers developing case-hardening grades for aviationWind turbine gearbox manufacturers facing high-cycle fatigue issuesEngineering consultancies specializing in gear fatigue analysis and certification

Business applications

Who can put this to work

Aerospace Engine Manufacturing

enterprise

Target: Aircraft engine and power gearbox manufacturers

If you are an aircraft engine manufacturer designing epicyclic gearboxes for Ultra-High Bypass Ratio engines — this project developed a validated material fatigue model and a recirculating gear test rig that lets you predict tooth root bending failure in the Very High Cycle Fatigue regime. This means you can certify new case-hardened steel gears faster, with fewer expensive full-scale tests, using data from 2 specialized German research partners.

Specialty Steel Production

enterprise

Target: Steel producers developing case-hardening grades for aerospace

If you are a specialty steel producer developing new case-hardening steel grades and need fatigue data to convince aerospace customers — this project generated VHCF material data for two new case-hardening steel developments, validated through a purpose-built test rig at RWTH Aachen. The FE-based strength analysis and weakest link models provide the kind of certified performance proof that aerospace OEMs require.

Industrial Gearbox Manufacturing

mid-size

Target: High-performance gearbox and transmission manufacturers

If you are a gearbox manufacturer dealing with unexpected fatigue failures in high-speed planetary gear systems — this project developed methods to predict material life in the Very High Cycle Fatigue regime using FE-based models validated against ISO 6336 standards. The material characterization techniques (X-ray diffraction, electron microscopy, metallography) can be adapted to your gear steels and operating conditions.

Frequently asked

Quick answers

What would it cost to license or access these material models and test data?

The project was publicly funded with EUR 2,365,530 under Clean Sky 2 (RIA). Licensing terms would need to be negotiated directly with the consortium — RWTH Aachen and Leibniz-IWT Bremen. As a publicly funded research project, some results may be available through open access, but proprietary test data and models likely require a licensing agreement.

Can this be applied at industrial scale for production gear certification?

The project built and commissioned a high-power recirculating gear test rig that was validated for operation. RWTH Aachen's gear testing environment is already officially approved by aircraft engine producers, which means the test infrastructure meets industrial certification standards. Scaling the material models to production use would require integration with existing design workflows.

Who owns the intellectual property from this project?

IP is shared between the 2 consortium partners: RWTH Aachen (WZL) and Leibniz-IWT Bremen, both German research institutions. As a Clean Sky 2 project, specific IP provisions of the Joint Undertaking apply. Companies interested in the material models or test rig access should contact the coordinator at RWTH Aachen.

Does this work only for aircraft gears or can it apply to other industries?

The VHCF material model and FE-based strength analysis methods were developed for case-hardened gear steels under aerospace conditions, but the underlying science — predicting fatigue life beyond conventional endurance limits — applies wherever gears operate at very high cycle counts. Wind turbines, high-speed rail transmissions, and industrial power gearboxes face similar fatigue challenges.

How validated are the results?

The project produced 8 deliverables including a demo deliverable: a high-power recirculating gear test rig that was assembled, commissioned, and performance-analyzed. Material data was generated for two new case-hardening steels, and the VHCF model was validated against experimental results. The testing facility at WZL is already approved by aircraft engine producers.

What is the timeline to adopt these results?

The project ran from 2019 to 2023 and is now closed. The material models and test data are complete. However, integrating VHCF predictions into a company's gear design process would require adaptation work — translating the research models into production design tools and validating them against your specific steel grades and operating conditions.

Consortium

Who built it

This is a tightly focused, all-German academic consortium with just 2 partners: RWTH Aachen (WZL — one of Europe's leading gear research labs) and Leibniz-IWT Bremen (materials science institute). There are zero industrial partners, zero SMEs, and the industry ratio is 0%. For a business looking to adopt these results, this means you are dealing exclusively with research institutions — which simplifies licensing negotiations but also means there is no industrial partner who has already adapted the technology for production use. The fact that WZL's testing facility is already approved by aircraft engine producers is a significant credibility signal, suggesting strong informal industry connections despite the purely academic consortium.

RHEINISCH-WESTFAELISCHE TECHNISCHE HOCHSCHULE AACHENCoordinator · DE
LEIBNIZ-INSTITUT FUR WERKSTOFFORIENTIERTE TECHNOLOGIEN-IWTparticipant · DE

How to reach the team

RWTH Aachen, WZL (Laboratory for Machine Tools and Production Engineering) — look for the gear technology or materials testing group lead

Order a report on this consortium See RHEINISCH-WESTFAELISCHE TECHNISCHE HOCHSCHULE AACHEN profile →

Next steps

Talk to the team behind this work.

Want an introduction to the MatCH4Turbo team at RWTH Aachen? SciTransfer can connect you with the right researcher and provide a tailored briefing on how their VHCF material models apply to your specific gear application.

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