skin85
Mechanical
- Mar 30, 2008
- 4
Hi all,
I'm attempting to verify some findings, in cosmos advanced professional, from a hammer test i have performed.
The experiment is looking at the mode shapes of a brake rotor. For the hammer experiment the disc was suspended on bungees, four in total(through the hubs). Each with a spring stiffness, k, of 6N/m.
I impacted the structure at 23 discrete locations and after performing some analysis and observing FRFs concluded that there were four dominant modes within a frequency range of 0-6000Hz. These modes occured at:
mode 1 1073Hz
mode 2 2430Hz
mode 3 3967Hz
mode 4 5555Hz
I'm now trying to replicate these environmental conditions in the software, but with no prior expeirience I'm having difficulty.
I have created an accurate SW model of the disc, assigned the correct material (grey iron) and used default mesh properties.
The restraint I used for the initial anaysis was "Elastic Connector", I applied this constraint to the hub surface and gave the properties "normal stiffness 24N/m total" and "shear stiffness 0N/m".
After running analysis on all modes within the specified 0-6000Hz frequency range the software returns 39 resonant frequencies (the first 6 are zero Hz). This is surely incorrect?
Any help on how I can improve the accuracy of the software boundary conditions would be greatly appreciated.
Regards
I'm attempting to verify some findings, in cosmos advanced professional, from a hammer test i have performed.
The experiment is looking at the mode shapes of a brake rotor. For the hammer experiment the disc was suspended on bungees, four in total(through the hubs). Each with a spring stiffness, k, of 6N/m.
I impacted the structure at 23 discrete locations and after performing some analysis and observing FRFs concluded that there were four dominant modes within a frequency range of 0-6000Hz. These modes occured at:
mode 1 1073Hz
mode 2 2430Hz
mode 3 3967Hz
mode 4 5555Hz
I'm now trying to replicate these environmental conditions in the software, but with no prior expeirience I'm having difficulty.
I have created an accurate SW model of the disc, assigned the correct material (grey iron) and used default mesh properties.
The restraint I used for the initial anaysis was "Elastic Connector", I applied this constraint to the hub surface and gave the properties "normal stiffness 24N/m total" and "shear stiffness 0N/m".
After running analysis on all modes within the specified 0-6000Hz frequency range the software returns 39 resonant frequencies (the first 6 are zero Hz). This is surely incorrect?
Any help on how I can improve the accuracy of the software boundary conditions would be greatly appreciated.
Regards
