EHD 글 편집

EHD is a RecurDyn toolkit for modeling 3-dimensional elasto-hydrodynamic lubrication. This toolkit enables RecurDyn to model the behavior of a lubricant film in a thin gap between rapidly-moving cylindrical surfaces and the hydrodynamic forces transmitted from the lubricant to the surfaces.

Because EHD in RecurDyn is tightly coupled with the mechanical system model, very realistic lubrication conditions can be analyzed. This enables RecurDyn EHD to significantly reduce the time and cost of development systems involving EHD lubrication.

RecurDyn EHD can model hydrodynamic lubrication and surface-to-surface contact phenomenon. The outer and inner cylindrical walls can be modeled as either flexible or rigid bodies.

For example, RecurDyn with the EHD toolkit can perform an accurate simulation of the behavior of an internal combustion engine that includes highly detailed and realistic journal bearing and piston lubrication.

RecurDyn Toolkit - EHD


  • Mass-conserving elasto-hydrodynamic lubrication (EHD), hydrodynamic forces, and lubricant film thickness can be analyzed.
  • Viscosity of lubricant film and roughness of boundary surface can be considered.
  • Asperity Contact Force results can be analyzed considering boundary surface.
  • EHD results on piston skirts, cylinder liners, and journal bearings can be displayed in the animation, as well as the lubricant film thickness and pressure.
  • Any of the contact surfaces in the journal bearings, pistons, or cylinders can be modeled as flexible bodies.
  • EHD Contour Plot results can be displayed as a 3D Surface or a Projection.

RecurDyn EHD - Features (Projection) RecurDyn EHD - Features (3D surface)  

  • Contour Plot optionally allows for pressures only over a specified limit to be displayed.
  • Hydrodynamic Forces and Asperity Contact Forces are reported separately.
  • Asperity Contact Forces includes Contact Friction.
  • For Rotational Lubrication, non-zero boundary pressures can be applied at both ends of the bearing.
  • For Rotational Lubrication, the volume flow rate results can be used to determine the flow rate that flows in and out axially.


EHD Bearing (Rotational Lubrication) : Models fluid lubrication between journal bearing surfaces rotating at high speeds. Various effects, such as the Oil Hole and Groove Effects, can be included.

  • Non-zero boundary pressures can be applied at both ends of the bearing.
  • Volume flow rate can be used to determine the in-flow and out-flow rates.

EHD Piston (Piston Lubrication) : Models fluid lubrication between a cylinder and a piston in which the piston can translate at high speed.

  • This toolkit allows effect of the tilting of the piston on the pressure and thickness of the lubricant film to be analyzed.
  • If the cylinder or piston is modeled as an RFlex body, the effect of body deformation on the pressure and lubricant thickness can also be analyzed. Complex piston shapes, including piston skirts, can be modeled.

RecurDyn EHD - Benefits

Application Examples

RecurDyn EHD - Applications

  • Prediction of high-speed rotational motion involving hydrodynamic lubrication in journal bearings of crankshaft.
  • Prediction of high-speed translational motion involving hydrodynamic lubrication of piston.
  • Optimized lubrication considering instantaneous changes of oil pressure due to piston skirt deformation
  • Optimized lubrication considering instantaneous changes of oil pressure due to minute changes in piston shape and cylinder liner shape