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ENDURANCE LIMIT OF ACTUAL BEARINGS DEPENDING ON OPERATING CONDITIONS, MATERIALS & MANUFACTURING

Objective


The analytical models which describe the contacts, the stress field, the initiation of crack and the conditions to reach the surface spalling have led to establish four typical criteria regarding the endurance limit (H1, H2, H3 and H4).

The fatigue tests conducted either on simulated contacts or on full bearings have been evaluated from damage point of view. The endurance limit of several materials has been obtained through the residual stress analysis of a wide range of samples.

In order to predict the endurance limit in relation with the residual stress versus depth, a representative parameter has been created: the characteristic deformation number.

The effect of temperature has been also determined on these steels :
* 100Cr6, M50-NIL and CRONIDUR 30

The values found on M50 correlated the H1 limit obtained from the analysis.

A part of the tests was devoted to contacts in gears.

The Barkhausen noise technic was used. A good correlation was observed with residual stress on 100Cr6 steel.
Deviation between calculated lives and services lives is due to a combination of material improvements,inadequate representation of the stress mechanism that cause failures and general oversimplification embodied in the general power law assumption.

This project proposes:

1. To support a significant progress in the development of a new fatigue model based on a physical/metallurgical microscopic approach with a macroscopic approach of the stress tensor (continuum mechanics).

2. To conduct monitored test in order to evaluate the real endurance limit of actual bearing steels and to identify the weight of influencing parameters:

- temperature

- hertzian stress

- hoop stress

- residual stress.

3. To achieve similar test in industrial situations,particularly in high speed conditions representing turbines engines applications.

4. To investigate damage effect on after service bearings and to correlate above analysis.

5. To investigate influence of similar parameters on the rolling/sliding contact subjected to similar fatigue phenomenon in gear applications.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

TURBOMECA
Address

64511 Bordes
France

Participants (9)

BMW ROLLS-ROYCE GMBH
Germany
Address
Hohemarkstraße 60-70
61440 Oberursel
FAG KUGELFISCHER GEORG SCHAFER KGAA
Germany
Address
Georg-sch Fer Straße 30
97421 Schweinfurt
Hispano-Suiza SA
France
Address
Rue Du Capitaine Guynemer
92270 Bois-colombes
Institut National des Sciences Appliquées (INSA)
France
Address
20 Avenue Albert Einstein
69621 Villeurbanne
Motoren- und Turbinen-Union München GmbH (MTU)
Germany
Address
Dachauer Straße 665
80995 München
RENAULT
France
Address
8-10 Avenue Emile Zola
92109 Boulogne Billancourt
Rolls Royce plc
United Kingdom
Address

BS12 7QE Filton
SNR ROULEMENTS
France
Address
1 Rue Des Usines
74010 Annecy
Société Nationale d'Études et de Construction de Moteurs d'Aviation (SNECMA)
France
Address
2 Boulevard Du Général Martial Valin
75724 Paris