Find Natural Frequency of Structure: Cube (Box) of Honeycomb Sandwich Panels

[kashoo]

What is exact procedure to find the Natural Frequency of a structure...i.e a cube (box) of Honeycomb Sandwich Panels...i have simulated the Modal Analysis in Ansys...there i got the natural frequency of very low amount ...almost 0.3Hz for First Mode,0.5 Hz for Second Mode and so on...i think it is very less amount ...How can i Practically Verify this Natural Frequency...please guide me in this area...what about Sine Sweep Test on Shaker...Can i do it on Impact Testing(Hammer+Accelerometer+Signal Analyzer+Data Accquisition ) ?
Plz tell me some useful links on web or Standard Method ASTM for verifying Natural Frequency of Structure...
What about Mathematical Modeling of this Cubical Box.

 

[kashoo]

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[ravenprp]

The natural frequency of a structure, in this case a cube (box) of honeycomb sandwich panels, can be determined through various methods, such as analytical calculations, experimental tests, or numerical simulations. In your case, you have simulated the modal analysis in Ansys and obtained the natural frequencies. However, you have concerns about the low values obtained and the need for practical verification.

To verify the natural frequencies obtained from your simulation, you can conduct experimental tests such as a sine sweep test on a shaker or an impact test using a hammer, accelerometer, signal analyzer, and data acquisition system. These tests can provide more accurate results and validate the simulation results. You can refer to ASTM standards such as ASTM E1050 for conducting a sine sweep test and ASTM E1875 for an impact test.

Another way to verify the natural frequencies is through mathematical modeling. This involves creating a mathematical model of the structure using the physical properties and dimensions of the honeycomb sandwich panels. The natural frequencies can then be calculated using mathematical equations and compared with the simulation results.

Useful links for verifying natural frequencies and mathematical modeling of structures include:

1. National Institute of Standards and Technology (NIST) - https://www.nist.gov/
2. American Society of Mechanical Engineers (ASME) - https://www.asme.org/
3. Society of Experimental Mechanics (SEM) - https://sem.org/
4. International Modal Analysis Conference (IMAC) - https://www.imac-online.org/
5. International Society for Structural Health Monitoring of Intelligent Infrastructure (ISHMII) - https://www.ishmii.org/

It is important to note that the natural frequencies of a structure can also be affected by various factors such as boundary conditions, material properties, and geometric imperfections. Therefore, it is recommended to conduct multiple tests and simulations to obtain more accurate results.