Nick GAZIS, CERN-BE/RF/PM & NTU-Athens 1

Test Module Working Group

04 April 2012

Update on the MODAL ANALYSIS of the Test Module supporting system in the LAB

Modal Analysis Report EDMS 1184906: Courtesy of T. Kostamovaara

Nick GAZIS, CERN-BE/RF/PM & NTU-Athens 2

Strategy

04 April 2012

Modal measurements for the supporting system of the Test Modules in the LAB: GOAL: To analyze the modal behaviour of the different configurations of the supporting system (girders, V-shaped supports and cradles) and identify the existing eigenfrequencies of the supporting system sub-assemblies.

Sub-assemblies: a. DB V-shaped supports;b. MB V-shaped supports;c. DB girder with integrated V-shaped supports and cradles assembled,d. MB girder with integrated V-shaped supports and cradles assembled.

Methodology: e. Accelerometers glued on the supporting components; f. Excitation force ( < 50 N) imposed with a special impact hammer (plastic-end tip);g. Signal received by the accelerometers and the impact hammer tip and then transmitted to a spectrum analyzer;h. Dedicated software interprets and analyses the measurements.

Comparison of: i. Preliminary simulation values/modes (EDMS doc : 1083833); j. Simulation values/modes (EDMS doc : 1098928);k. Modal measurements/modes (EDMS doc : 1159189), l. Modal measurements/modes (EDMS doc : 1184906 ).

Nick GAZIS, CERN-BE/RF/PM & NTU-Athens 3

Testing Configuration

04 April 2012

Accelerometers

Courtesy of T. Kostamovaara

DB T-0 (LAB) Girder (Boostec)

Excitation method

The accelerometers were assembled on key positions for the modal measurements so as to identify the modal behaviour or the supporting system components (V-shaped supports, girder, cradles, etc.). Such key points are the 1, 6, 10, 15 and 20 of the figure.

Nick GAZIS, CERN-BE/RF/PM & NTU-Athens 4

Results

04 April 2012

Rigid body mode: 8 Hz

1st (bending) mode: 59 Hz 2nd mode: 141 Hz

Rigid body mode: 15 Hz Rigid body mode: 19 Hz Rigid body mode: 37 Hz

Courtesy of T. Kostamovaara

*RIGID BODY MODE: The distance between any two given points of a rigid body remains constant in time regardless of external forces exerted on it.

1st simulated (bending) mode: 50 Hz

8_Hz_Rigid_mode.avi15_Hz_Rigid_mode.avi 19_Hz_Rigid_mode.avi 37_Hz_Rigid_mode.avi

59_Hz_First_mode.avi141_Hz_Second_mode.avi

Nick GAZIS, CERN-BE/RF/PM & NTU-Athens 5

Results – Conclusions

04 April 2012

Mode Measured Frequency [Hz]

Simulated Frequency [Hz]

Rigid 8 -Rigid 14 -Rigid 19 -Rigid 37 -

1st 59 502nd 141 1313rd - 1764th - 2145th - 2466th - 285

The simulated 1st and 2nd modal shapes are confirmed by the measurements.

Rigid body modes measured in between 0-50 Hz: Resonance ~50 Hz with smaller damping needs to be avoided.

The alignment plates under the cradles can generate a series of body modes.

Stability could be optimized by rigidifying the alignment plates (e.g. cast them in cement). Increase the frequency of the 1st bending mode (if needed) by dedicated design

optimization of the girder cross section.

Courtesy of T. Kostamovaara

Nick GAZIS, CERN-BE/RF/PM & NTU-Athens 6

Summary and Future steps

04 April 2012

Summary of accomplished tasks:•Modal simulation for the Main Beam and the Drive Beam configurations of the LAB; •Modal analysis for the Main Beam and Drive Beam V-shaped supports;•Modal analysis of the sub-assembly of the Drive Beam girder, V-shaped supports and cradles.

Future tasks:•Modal analysis of the sub-assembly of the Main Beam girder, V-shaped supports and cradles;

Comments are always

welcome!