Methodology to improve mode identification and modal parameter extraction for rotor dynamic analysis

• Main Authors: Rafael Alfonso Figueroa Díaz, J. E. Aguirre Romano, A. Balvantín García, P. Cruz Alcantar
• Format: Article
• Language: English
• Published: JVE International 2017-06-01
• Series: Journal of Vibroengineering
• Subjects: modal balancing; optimum modal parameters; rotation systems; response diagrams
• Online Access: https://www.jvejournals.com/article/17818

This work presents the development of a methodology that, through the use of the coordinate transformation method, identifies the ideal modal parameters that should be used during the modal balancing process as well as allows eliminating the computational modes generated during the rotor response diagram extraction process. There is currently a wide variety of methods for structures that allow extracting limited modal parameters, such as: previous knowledge of the number of modes, adjustment of computational or spurious modes, close mode identification problems, and others. However, localizing the phase angle in rotation systems in any angular position and through complex coupling of the vibration modes does not ensure that the methods developed for structures conserve the same performance during the adjustment process. As regards the line of investigation into modal balancing, a method is proposed that allows ensuring that the modes found are real modes of the system and that through direction tracking where a single vibration mode is excited, the optimum extraction position of the modal parameters used in the balancing process can be determined. The proposed methodology was developed using a linear model and was applied in a field turbogenerator to identify the vibration modes present in the response diagrams.