Keywords: high speed cutting, FEM, experimental modal analysis, dynamic response of structure, frequency domain decomposition, data processing, spectral analysis of structures, natural frequencies and modes.

Experimental dynamic testing is an effective method to evaluate technological process structural performance parameters and calibrate structural models. This paper presents the dynamic analysis of the high speed cutting (HSC) production equipment for cutting steel bars of 50 to 70 mm diameter. Nowadays, this machine-set seems to be the European prototype for cutting machines with the largest cutting bar diameter. An extreme dynamic response of the HSC structure is due to the technological cyclic impulse loading. A dynamic analysis was completed using theoretical and experimental modal analysis of the HSC structure steel frame. For the theoretical analysis the two versions of the numerical model were applied according to the HSC structure project design data. These HSC structure computational models were defined by: (1) a finite element model with empty damper oil tanks and (2) a finite element model with full damper tanks (filled with a specific oil damping medium). The modal analysis computational results (natural frequencies and modes of natural vibration) were compared with the experimental modal analysis results (MAC). The HSC structural response was also measured. The amplitude time history was compared with the prescribed amplitude limits (accelerations, velocities and the displacement performance amplitude tool factory limits). This enabled an improved analytical finite element model (with three-dimensional elements) for the HSC structure to be created. Modification to reduce the level of the vibrations and noise in the processing hall and also to reduce the frame structure members dynamic stresses was accomplished. This enables the service life of the HSC production equipment To be prolonged.

The natural frequencies and the modes of natural vibration of mechanical systems are one of the most important structural dynamic properties. Experimental modal analysis (EMA) helps us obtain better information regarding to elements, boundary conditions and mass redistribution and structural stiffness as a whole [1,2,3,4,5].

1

NI LabVIEV Modal Analysis (LabVIEV MA), Software package, National Instrument, USA.

2

Hjelm H.P., Brincker R., Graugaard-Jensen J., Munch K., "Determination of Stress Historie in Structures by Natural Input Modal Analysis", Proceedings of The 23rd International Modal Analysis Conference (IMAC), Orlando, Florida, 2005.

3

Aenelle M.A., Brincker R., Canteli A.F., "Some Methods to Determine Scaled Mode Shapes in Natural Input Modal Analysis", Proceedings of the 23rd International Modal Analysis Conference (IMAC) Orlando, Florida, 2005.

4

Bencat J., Papán D., "Modal Analysis of Foundation Structure TG11 in EMO Mochovce", In: Teoretyczne Podstawy Budownictwa, 1-3 July, 2003, Moscow, Warszawa Univ. Press, pp. 39-44, 2003.

5

Benjedov A. "Advanced in Piezoelectric Finite Element Modeling of Adaptive Structural Elements Survey", Computers and Structures, 76, 347-363, 2000. doi:10.1016/S0045-7949(99)00151-0

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