Overview
ISO 7905-4:2022 - Plain bearings - Bearing fatigue - Part 4 specifies a laboratory method to determine the endurance limit in fatigue for half-bearings made from a metallic multilayer bearing material. The standard defines specimen preparation, test setup, loading conditions, measurement procedures and result presentation for fatigue testing of ready-to-use half-bearings. It preserves residual manufacturing stresses and focuses on stresses in the crown area that typically govern fatigue life.
Key topics and technical requirements
- Test objective: determination of the fatigue endurance limit (σ_el) for half-bearings of metallic multilayer materials.
- Specimens: half-bearings ready for use; dimensions and layer thicknesses must be determined (microsection) after testing.
- Test principle and setup:
- Specimens clamped at one end and loaded radially at the relief parting-line runout (cantilever-type load).
- Load fluctuates between tension and compression; a mean tensile or compressive prestress may be applied to study mean-stress effects.
- Frequency range: 50 Hz to 80 Hz.
- Tests conducted in lubricant bath or in air at controlled temperature with tolerance ±2 °C.
- Measurements and calculations:
- Nominal surface stress on bearing back measured by strain gauge or derived from radial force and cantilever beam theory.
- Annex A provides stress-evaluation methods, dimensionless coefficients and worked examples for two- and three-layer systems.
- Overlay stresses can be approximated via Young’s modulus ratios when overlay thickness is negligible.
- Crack detection and failure criteria:
- Crack detection by dye penetrant in accordance with ISO 4386-3 or by microscopic inspection.
- Data presentation:
- Endurance limit reported as σ-N (stress vs cycles) curves at specified temperature (±2 °C).
- Typical termination for practical σ-N testing is 5 × 10^6 cycles; endurance limits can be quoted at specific cycles (e.g., 3×10^6, 10×10^6, 25×10^6, 50×10^6).
- Statistical evaluation recommended due to scatter in fatigue results; Haigh diagrams (stress amplitude vs mean stress) suggested for additional presentation.
Applications
- Qualification and comparison of metallic multilayer plain bearing materials for automotive, industrial and heavy machinery plain bearings.
- Fatigue life assessment during bearing material development, quality control and failure analysis.
- Design validation where endurance limits of multilayer bearing linings are required for reliable plain-bearing systems.
Who should use this standard
- Bearing manufacturers and material suppliers
- Test laboratories and R&D teams in tribology and materials engineering
- OEMs and design engineers specifying bearing fatigue performance
- Quality assurance and certification bodies
Related standards
- ISO 4386-3 - Non-destructive penetrant testing (referenced for crack detection)
- ISO 7905-3 - Tests on plain strips of metallic multilayer bearing material
- ISO 3548-1, ISO 4378-1 - Related plain bearing design, materials and testing standards
Keywords: ISO 7905-4:2022, plain bearings, bearing fatigue, metallic multilayer bearing material, half-bearings, endurance limit, fatigue testing, σ-N curves.