Identification of bearing load by three section strain gauge method: Theoretical and experimental research

• Bearing load identification method based on three section strain gauge is proposed.
• It can reduce the modeling error, especially for the machines with irregular parts.
• This method can be used to identify the specific bearing load.
• It is suitable for entire shaft load distribution study with high fault tolerant.
• The accuracy of the method depends on the strain gauge locations.

Reasonable bearing load distribution is important for the safe and reliable operation of rotating machinery. However, it is difficult to measure bearing load in field. This paper puts forward a bearing load identification method based on the measured three section strain values. Shaft is divided into several sections at strain gauge locations. The force and moment equilibrium equations are set up and assembled to form bearing load solving equations. This method can reduce the modeling error, especially for the machines with irregular rotating parts. It can also be applied for the entire shaft system bearing load distribution study with high accuracy and fault tolerant. Test was done on a rotor-bearing system rig. Bearing load distribution in different shaft alignment states is identified and analyzed. Test results show that the bearing load distribution varies sensitively and linearity to the change of bearing elevation. Further research shows that the accuracy of the method depends on the strain gauge locations. It would be best to place the strain gauge at location where the bending moment is sensitive to the change of bearing load. Moreover, mounting the strain gauge further from the bearing reduces the relative error due to the exact reaction point location is not known, which influences the accuracy of beading moment arm from the strain gauge location to the reaction point.