m1esk
Aerospace
- Apr 6, 2011
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Please give any comments or suggestions...
A metallic assembly with bolted joints, is mounted on a composite structure. It has been designed and analysed, with the FEM including the composite structure; the critical stresses have been derived. Now, a sine-sweep will be performed with shaker connected to the composite structure.
To avoid damage to the hardware, the accelerometers will be monitored. The prediction method is as follow:
1. Accelerometers are placed on various parts of the metallic assembly.
2. Analytical FRFs for the accelerometers and critical stresses are derived from FEM.
3. The analytical acceleration FRFs are compared with the stress FRF; the matching accelerometer(s) will be used as the control to monitor the critical stresses.
4. So, at a certain resonance the magnitude of the control-acceleration is assumed to be proportional to the stress at the same frequency.
5. The sine-sweep will begin with a low-level excitation. By looking at the peak acceleration response at the control-meters, the stress is extrapolated to full-level value.
6. The extrapolated stress is reviewed before deciding to go to full-level sine-sweep.
Any help is appreciated.
Thank you all.
A metallic assembly with bolted joints, is mounted on a composite structure. It has been designed and analysed, with the FEM including the composite structure; the critical stresses have been derived. Now, a sine-sweep will be performed with shaker connected to the composite structure.
To avoid damage to the hardware, the accelerometers will be monitored. The prediction method is as follow:
1. Accelerometers are placed on various parts of the metallic assembly.
2. Analytical FRFs for the accelerometers and critical stresses are derived from FEM.
3. The analytical acceleration FRFs are compared with the stress FRF; the matching accelerometer(s) will be used as the control to monitor the critical stresses.
4. So, at a certain resonance the magnitude of the control-acceleration is assumed to be proportional to the stress at the same frequency.
5. The sine-sweep will begin with a low-level excitation. By looking at the peak acceleration response at the control-meters, the stress is extrapolated to full-level value.
6. The extrapolated stress is reviewed before deciding to go to full-level sine-sweep.
Any help is appreciated.
Thank you all.
