Sint Technology
  • Company
    • Mission
    • Recognitions
    • Partnerships
    • Customers
    • Company Policy
    • TIC Compliance
  • Products
    • MTS3000 – Restan
    • MTS3000 – Ring Core
    • DRMS Cordless
  • Services
    • Thermodynamic Testing
    • Mechanical Testing
    • Residual Stress Testing
  • Integrated solutions
    • Data acquisition and diagnostic systems
    • Long term monitoring systems – Industry 4.0
    • Custom Solutions
  • Training
    • Level I strain gauge course and examination
    • Level II strain gauge course and examination
    • Residual stress Training
  • English
  • Search
  • Menu Menu
  • Youtube
  • LinkedIn
C
O
N
T
A
C
T
S
Hammer test

Experimental Modal Analysis

Location

Florence – test bench

Problem

High vibration levels were recorded on front journal bearing (in correspondence of plinth No. 1) of the steam turbine

Overview

High vibration levels were recorded on the probe SV-2H on the steam turbine front journal bearing, when rotational speed approached the maximum value (1xRev component at about 176 Hz).
Aim of the test was to determine if any resonance frequency of the basement could be excited by the steam turbine at maximum speed so that it could justify the high vibration level recorded.
Eventually, some modifications of the structure could be suggested by the experimental results.

Activities

SINT Technology suggested to carry out an experimental modal analysis (impulse method) in order to verify the structural response of the system and, if necessary, to make some modifications on the structure in order to move up or down the resonant frequency.

Experimental analysis

Figure. 2 Measurement points

Results

Figure. 3 Synthesized FRF
Figure. 4 Stabilization diagram
Figure. 5 Mode deflection shape

The experimental modal analysis carried out on the plinth No.1 showed a natural frequencies at 172Hz, that is a value near to the 1xRev component with the steam turbine running at maximum speed.

Suggested modification

Conclusion

The experimental modal analysis carried out on the plinth No.1 showed a natural frequencies at about 172Hz, that is a value near to the 1xRev component with the steam turbine running at maximum speed.
Considering the corresponding modal shape, some modifications were implemented in order to move the frequency (increasing the stiffness).
After these modifications, the amplitude of the response of the structure at that frequency widely decreased as shown in Figure 8; therefore the modifications have been effective for moving the resonance away from that condition.

Figure. 8 Response before and after modification

Advantages

  • Quick problems troubleshooting thanks to real time data elaboration
  • Quick Modal parameter estimation based
  • Wide range of validation tools such as modal assurance criterion, modal phase collinearity, mean phase deviation, etc
  • Real time deflection shape

Case Histories

  • Experimental Modal Analysis
  • Reciprocating compressor diagnostics
  • Torque analysis on gear box shaft
  • Total Temperature Rakes
  • Cultural heritage
  • Monitoring and diagnostics systems
  • Motion
  • Residual stresses
© Copyright - SINT Technology s.r.l. | VAT n. IT04185870484 | Via delle Calandre, 63 50041 - Calenzano (FI) - ITALY | Tel: +39 055 8826302 | E-mail: info@sintechnology.com
Powered by Playnet
Scroll to top