Dynamic Analysis of CNC Machine Tool Structures Using FBGMT and R-Flex Flexible Multibody Dynamics Approaches

Abstract:

This study presents an integrated rigid flexible dynamic analysis of a CNC machine tool column using the Full Body General Motion Transfer (FBGMT) method and R-Flex flexible body modeling in RecurDyn, validated through comparison with ANSYS finite element modal results. The FBGMT approach simulated the vertical translation of the spindle head driven by a ball screw linear guide system, generating realistic motion data for structural evaluation. The R-Flex model converted the column into a flexible body using an RFI-based contact method, enabling the assessment of deformation, stress, and strain at three distinct tool head positions top, mid, and bottom. Modal analysis was performed in both RecurDyn and ANSYS under matched geometry, mesh density, and boundary conditions to verify frequency and mode shape consistency. Results show that displacement and stress increase as the tool head moves downward, with all responses remaining within elastic limits. Frequency deviation between RecurDyn and ANSYS remained within engineering tolerance, and mode shapes demonstrated strong correlation. This integrated workflow demonstrates a robust methodology for predicting CNC structural performance under realistic motion induced loading.

• Periodical: Defect and Diffusion Forum (Volume 453)
• Pages: 33-44
• DOI: https://doi.org/10.4028/p-Zzp2K0
• Online since: July 2026
• Authors: Yunn Lin Hwang*, Nabeel Ahmad
• Keywords: CNC Machine Tool, FBGMT, Modal Analysis, Multibody Dynamics, R-Flex

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