Normal Mode modelling by using exciter

Please tell me how to create boundary system of modal analysis as my picture at attachment below by using normal mode modul (sol103). My point is we do by some exciter (hummer) position at each case. Now we assume the object as a plate with 300x300x5; E = 72,400 ; v = 0.33 ; density = 2.67E-9. Postition of hummer : 1. at center of plat, 2. at one of the corner of the plate. Hopefully this will give different value of frequency at each position.

0 Hrishikesh Phadke over 5 years ago

SOL 103 will describe the structure in terms of its natural frequency and mode shapes. There is no external excitation in SOL 103.

You need to perform a SOL 111 to excite the structure and study how the natural frequency affects the response of the structure. You will notice that the response amplifies as you get closer and closer to the natural frequency of the structure. You will require 2 seperate runs of SOL 111 for the 2 conditions.

Postition of hummer : 1. at center of plat, 2. at one of the corner of the plate.
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0 asmarianto over 5 years ago

Ok thank you for your fast response, so please give me video of the solution from sol 111 by that condition. If this module can solve my case, i will consider to use this later. Thank you.
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0 Hrishikesh Phadke over 5 years ago

I am attaching Dynamics workbook which goes through example problems from SOL 103-111. Step -by-step procedure to setup the problem is provided using Patran.

Attached Files (1)

nas102_dynamic_workbook.pdf
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0 asmarianto over 5 years ago

Okay, i will try to explore this workbook. I have a question, is the frequency result at sol 111 is the natural frequency?and if it is not how to determine the natural frequency by exciting the structure with impact hummer? thank you.
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0 Hrishikesh Phadke over 5 years ago

Sol 103 gives the natural frequency of the structure. SOL 111 will give you how the structure responds to the external excitation such as impact hummer.

Users normally does a SOL 103 first to understand the structural frequencies, then they can modify the structure to avoid a certain excitation frequencies being close to the natural frequencies. This way avoid resonating of the structure and reduce vibrations.
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