ISO/TS 31657-3:2020

Overview

ISO/TS 31657-3:2020 is an ISO technical specification that provides functions and characteristic values for the calculation of hydrodynamic tilting‑pad journal bearings under steady‑state (stationary) conditions. It covers selected tilting‑pad designs with four or five pads, both centrally and eccentrically supported, and with pad angular spans Ω = 80°, 60° and 45°. The tabulated and plotted functions in this document are intended to support operationally safe design according to ISO/TS 31657-1 and are based on the assumptions and boundary conditions defined in that Part 1.

Key topics and requirements

• Characteristic values for tilting‑pad bearings: Dimensionless parameters required for design (static and dynamic values) are listed in tables and graphs.
• Supported configurations: Bearings with four or five tilting pads, centrally (Ω = 0.5) or eccentrically (Ω = 0.6) supported pivots, and multiple pad spans (80°, 60°, 45°).
• Static characteristic parameters: Includes Sommerfeld number, relative eccentricity, attitude angle, minimum film thickness, friction parameter, lubricant flow rates, and film pressure products - defined consistently with ISO/TS 31657-1.
• Dynamic characteristic parameters: Non‑dimensional lubricant film stiffness and damping coefficients needed for rotordynamic analyses.
• Data presentation: Functions are provided in tabular form and plotted curves (Annex A shows characteristic curves for selected cases).
• Scope limitation: Applies only to stationary operating states and to the specific geometries and assumptions stated; symbols and calculation examples are referenced to ISO/TS 31657-1.
• Extensibility: The calculation method of ISO/TS 31657-1 can be applied to other tilting‑pad designs if equivalent numerical solutions of the underlying equations are available.

Applications and users

Who uses ISO/TS 31657-3:2020 and why:

• Bearing designers and OEMs: To size and specify hydrodynamic tilting‑pad journal bearings with confidence in static and dynamic performance.
• Rotating‑machinery and turbomachinery engineers: For rotordynamic modelling, stability analysis, and selection of bearing geometry and pad profiles.
• Tribologists and lubrication engineers: To estimate film thickness, friction and lubricant flow parameters under steady operation.
• Maintenance and reliability teams: To verify design margins and interpret operational limits for retrofits or troubleshooting. Practical uses include safe bearing design, input data for rotordynamic simulations, comparison of pad geometries, and pre‑validation of bearing stiffness/damping and thermal behavior.

Related standards

• ISO/TS 31657-1 - referenced for symbols, assumptions and calculation methods (calculation examples included there).
• ISO/TS 31657 series - additional parts and related guidance are listed on the ISO website.

Keywords: ISO/TS 31657-3:2020, tilting-pad journal bearings, hydrodynamic plain journal bearings, characteristic values, Sommerfeld number, steady-state bearing design, bearing stiffness and damping.