Application of a low frequency moment shaker for vibration testing

Martin W. Trethewey, Leonard L. Koss, Jeremy S. Trethewey

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

A novel device know as a Frequency Shifting Shaker (FSS) has been previously proposed by Koss for low frequency (less that 1 Hz) vibration excitation. The system consists of oscillating an eccentric mass shaker along an axis (i.e., y-axis) perpendicular to an imbalance forcing function axis (i.e., z-axis). The system produces a dynamic excitation moment, instead of a point force, at the operational sideband frequencies. The inherent operation of the device produces a `modal shaker' in that it only excites a mode when the sum or difference frequency coincides with a natural frequency. The device produces a controllable high amplitude excitation at a very low frequency (i.e., 0.5 Hz) making the technique well suited for vibration testing of large structures. Previous work has demonstrated the fundamental feasibility with a laboratory model. The objective of this paper is to report on experiences gained with a full scale prototype FSS system with a large test structure (inertial vibration isolation test bed). The results from two tests are compared; 1) a traditional modal analysis using an impact test and; 2) an Operating Deflection Shape (ODS) analysis using the FSS as the excitation. The comparison was excellent provided the FSS was capable of sufficiently exciting the mode.

Original languageEnglish (US)
Pages (from-to)87-92
Number of pages6
JournalProceedings of the International Modal Analysis Conference - IMAC
Volume1
StatePublished - Jan 1 2000

Fingerprint

Modal analysis
Natural frequencies
Testing

All Science Journal Classification (ASJC) codes

  • Engineering(all)

Cite this

@article{120c3e98e5654cb2b51a4035f0cd892f,
title = "Application of a low frequency moment shaker for vibration testing",
abstract = "A novel device know as a Frequency Shifting Shaker (FSS) has been previously proposed by Koss for low frequency (less that 1 Hz) vibration excitation. The system consists of oscillating an eccentric mass shaker along an axis (i.e., y-axis) perpendicular to an imbalance forcing function axis (i.e., z-axis). The system produces a dynamic excitation moment, instead of a point force, at the operational sideband frequencies. The inherent operation of the device produces a `modal shaker' in that it only excites a mode when the sum or difference frequency coincides with a natural frequency. The device produces a controllable high amplitude excitation at a very low frequency (i.e., 0.5 Hz) making the technique well suited for vibration testing of large structures. Previous work has demonstrated the fundamental feasibility with a laboratory model. The objective of this paper is to report on experiences gained with a full scale prototype FSS system with a large test structure (inertial vibration isolation test bed). The results from two tests are compared; 1) a traditional modal analysis using an impact test and; 2) an Operating Deflection Shape (ODS) analysis using the FSS as the excitation. The comparison was excellent provided the FSS was capable of sufficiently exciting the mode.",
author = "Trethewey, {Martin W.} and Koss, {Leonard L.} and Trethewey, {Jeremy S.}",
year = "2000",
month = "1",
day = "1",
language = "English (US)",
volume = "1",
pages = "87--92",
journal = "Proceedings of the International Modal Analysis Conference - IMAC",
issn = "1046-6770",
publisher = "Society for Experimental Mechanics",

}

Application of a low frequency moment shaker for vibration testing. / Trethewey, Martin W.; Koss, Leonard L.; Trethewey, Jeremy S.

In: Proceedings of the International Modal Analysis Conference - IMAC, Vol. 1, 01.01.2000, p. 87-92.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Application of a low frequency moment shaker for vibration testing

AU - Trethewey, Martin W.

AU - Koss, Leonard L.

AU - Trethewey, Jeremy S.

PY - 2000/1/1

Y1 - 2000/1/1

N2 - A novel device know as a Frequency Shifting Shaker (FSS) has been previously proposed by Koss for low frequency (less that 1 Hz) vibration excitation. The system consists of oscillating an eccentric mass shaker along an axis (i.e., y-axis) perpendicular to an imbalance forcing function axis (i.e., z-axis). The system produces a dynamic excitation moment, instead of a point force, at the operational sideband frequencies. The inherent operation of the device produces a `modal shaker' in that it only excites a mode when the sum or difference frequency coincides with a natural frequency. The device produces a controllable high amplitude excitation at a very low frequency (i.e., 0.5 Hz) making the technique well suited for vibration testing of large structures. Previous work has demonstrated the fundamental feasibility with a laboratory model. The objective of this paper is to report on experiences gained with a full scale prototype FSS system with a large test structure (inertial vibration isolation test bed). The results from two tests are compared; 1) a traditional modal analysis using an impact test and; 2) an Operating Deflection Shape (ODS) analysis using the FSS as the excitation. The comparison was excellent provided the FSS was capable of sufficiently exciting the mode.

AB - A novel device know as a Frequency Shifting Shaker (FSS) has been previously proposed by Koss for low frequency (less that 1 Hz) vibration excitation. The system consists of oscillating an eccentric mass shaker along an axis (i.e., y-axis) perpendicular to an imbalance forcing function axis (i.e., z-axis). The system produces a dynamic excitation moment, instead of a point force, at the operational sideband frequencies. The inherent operation of the device produces a `modal shaker' in that it only excites a mode when the sum or difference frequency coincides with a natural frequency. The device produces a controllable high amplitude excitation at a very low frequency (i.e., 0.5 Hz) making the technique well suited for vibration testing of large structures. Previous work has demonstrated the fundamental feasibility with a laboratory model. The objective of this paper is to report on experiences gained with a full scale prototype FSS system with a large test structure (inertial vibration isolation test bed). The results from two tests are compared; 1) a traditional modal analysis using an impact test and; 2) an Operating Deflection Shape (ODS) analysis using the FSS as the excitation. The comparison was excellent provided the FSS was capable of sufficiently exciting the mode.

UR - http://www.scopus.com/inward/record.url?scp=0033876728&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0033876728&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:0033876728

VL - 1

SP - 87

EP - 92

JO - Proceedings of the International Modal Analysis Conference - IMAC

JF - Proceedings of the International Modal Analysis Conference - IMAC

SN - 1046-6770

ER -