Tribology Letters

, 67:50 | Cite as

On the Assessment of Mechanical Degradation of Grease Using Entropy Generation Rate

  • K. P. Lijesh
  • M. M. KhonsariEmail author
Original Paper


A methodology for continuous monitoring of grease degradation subjected to mechanical shearing is proposed. It is hypothesized that the mechanical degradation of grease is akin to the running-in process in a tribo-pair with both transient and steady-state regimes. To validate the hypothesis, a series of mechanical shearing tests are performed on three grades of grease: NLGI 00, NLGI 1, and NLGI 2.5 by employing a rheometer. From the results, a more effective method using the entropy generation rate is proposed for continuous monitoring of grease degradation. The proposed method is extended to estimate the time for a grease subjected to mechanical shearing to degrade to a lower grade. The efficacy of this method is demonstrated via long duration testing in a custom-built ball-bearing test apparatus.


Entropy generation rate Transient regime Steady-state regime Grease degradation 



This research was conducted at LSU Center for Rotating Machinery and funded in part by NLGI (LSU #46895). The authors gratefully acknowledge this support.


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Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Department of Mechanical Engineering and Industrial EngineeringLouisiana State UniversityBaton RougeUSA

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