Technical Support

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Released in October 2017, RecurDyn V9R1 has enhanced modeling capabilities and contact analysis for MBD (Multi-Body Dynamics) analysis. Upgrading the Mesher core engine for easier and more accurate MFBD (Multi-Flexible Body Dynamics) analysis and adding new toolkits for multidisciplinary analysis solutions implemented in one environment will maximize user’s design performance.

Let’s take a closer look at the EHD (Elasto-Hydrodynamic Lubrication) toolkit in this article.

RecurDyn now contains 2 EHD toolkits: Rotational Lubrication toolkit and the Piston Lubrication toolkit. These toolkits enable RecurDyn to analyze the behavior of a lubricant film in the thin gap between rapidly-moving cylindrical surfaces and the hydrodynamic forces transmitted from the lubricant to the surfaces.

The Rotational Lubrication toolkit is for modeling primarily rotational motion, such as the motion found in journal bearings. The Piston Lubrication toolkit is for modeling primarily translational motion. It also supports RFlex (Flexible) Body analysis.


This article is for the introduction of EHD Toolkit and EHD Tutorial.

An additional license is required to use  EHD Toolkit

If you would like to use EHD Toolkit, please refer to 'How to apply for trial license of EHD Toolkit' below.

[How to apply for trial license of EHD Toolkit]

An additional license is required to use the EHD toolkit.If you would like to use the trial version of EHD toolkit, please contact us with the following information. (Please refer to Contact Us page)

  • Company:
  • Name:
  • Job title:
  • Tel. number or E-Mail:
  • Active product (RecurDyn):


EHD (Elasto-Hydrodynamic Lubrication) Overview

The EHD (Elasto-Hydro Dynamic) Toolkit is released in V9R1. In V8R5, RecurDyn began supporting the EHD bearing in the RecurDyn/Bearing Toolkit. In V9R1, The piston lubrication EHD is also developed. The EHD bearing entity and the new piston lubrication entity are released as the independent RecurDyn/EHD toolkit.


  • Features
    • Elastic Hydrodynamic Force
    • Asperity Contact Force
    • Consider Viscosity
    • Consider Roughness
    • EHD Force Contour Display
    • Export Result Data



Interactions between MFBD and EHD




What is EHD?

  • The goal of hydrodynamic lubrication is to add a proper lubricant, so that it penetrates into the contact zone between rubbing solids and creates a thin liquid film. This film separates the surfaces from direct contact. In general, this reduces friction and can consequently reduce wear, since friction within the lubricant is less than between the directly contacting solids.
  • History of lubrication theory goes back to 1886 when O. Reynolds published famous equation of the fluid film flow in the narrow gap between two solids. This equation carries his name and forms a foundation of the lubrication theory.



Schematic Diagram for Piston Lubrication



Fluid Lubrication Region: Governing Equation



Lubrication Region and Contact Region



Contact Region: Governing Equations




EHD Tutorial

EHD Toolkit Tutorial & Example files