Publication detail

Analysis of operational deflection shapes of the shaker armature near upper frequency limit

HAVRÁNEK, Z. BENEŠ, P.

Original Title

Type

conference paper

Language

English

Original Abstract

The paper deals with practical analysis of operational deflection shape of the top surface of the electrodynamic shaker armature near upper frequency limit below main resonance. The vibration test system with maximal sine force of 35 kN has been examined for excessive difference of vertical vibration acceleration between the center of circular shaker armature with diameter of 640 mm and its edges. With the control accelerometer in the center of the armature, there was thirty times higher acceleration on the edges at upper frequency limit of the shaker (2000 Hz). This difference has been firstly examined by contact measurement with piezoelectric accelerometers in certain points and afterwards with single point laser Doppler vibrometer enhanced with galvo-mirror system for the fast scanning of the whole armature surface. With scanning measurement procedure the operational deflection shape of the armature has been evaluated during sine force excitation of the vibration system. Detected deflection of the tabletop surface has umbrella-shape with very high displacement on the edges. This excessive difference in acceleration between recommended control point and the rest of the armature led to the armature damage in the past. The umbrella-shape vibrations of the armature indicate high friction in the central bearing or very high damping in the armature internal support which is necessary for handling heavy loads on the shaker table. To avoid further damage of the armature and equalization of the vibration amplitude on the whole surface, special dural stiffening plate with bolts arranged in concentric circles has been made. After several measurements of the deflection shapes of the armature equipped with the plate, necessary positions of the mounting bolts has been identified. Finally only half the number of bolts has been fitted and it led to the vibration acceleration variance on the whole tabletop within 20 percent.

Keywords

operational deflection shapes, vibrodiagnostics, non-contact vibration measurement, electrodynamic vibration exciter, shaker armature

Authors

HAVRÁNEK, Z.; BENEŠ, P.

RIV year

2013

Released

7. 7. 2013

Publisher

International Institute of Acoustic and Vibration

Location

USA

ISBN

978-616-551-682-2

Book

Proceedings of the 20th International Congress on Sound and Vibration

ISBN

2329-3675

Periodical

International Journal of Acoustic and Vibration

State

United States of America

Pages from

Pages to

Pages count

BibTex

@inproceedings{BUT101904,
  author="Zdeněk {Havránek} and Petr {Beneš}",
  title="Analysis of operational deflection shapes of the shaker armature near upper frequency limit",
  booktitle="Proceedings of the 20th International Congress on Sound and Vibration",
  year="2013",
  journal="International Journal of Acoustic and Vibration",
  pages="1--8",
  publisher="International Institute of Acoustic and Vibration",
  address="USA",
  isbn="978-616-551-682-2",
  issn="2329-3675"
}