Frequency of Timoshenko beam with crack

[georg2976]

Hello people,

I am new here. I want to define crack in Timoshenko beam and obtain natural frequency (first mode or many).

1. So I need to set properties of the beam?
2. To put the crack somewhere in the beam?
3. To obtain the frequencies for free vibration without damping?

Regards!!!

 

[rb1957]

yes, you're very new here to ask such an open, ill-defined, question.

what FEA are you using ? does it analyze cracks ?

i'd start with looking at the manual for a dynamic example problem. see how that's done, and what you need to specify (yes, you'll need to define a set of properties).

then look for how it models cracks. you might siply dupicate some nodes (so that adjacent elements don't share common nodes).

oh, and put on your asbestos under-wear, i think you're about to get flamed.

 

[georg2976]

Can we start to help me how to get the frequencies without crack for any beam, for any boundary conditions?

 

[rb1957]

sounds like a basic problem that any dynamics textbook will work you through.

have you tried googling ?

is this a student post ??

 

[georg2976]

I need steps how to obtain in Ansys program that? Sorry, maybe I didn't write.

 

[flash3780]

Here's a paper on determining the natural frequencies of a cracked beam. Is this helpful?

http://www.math.cornell.edu/~rand/randpdf/mandar.pdf

//signed//
Christopher K. Hubley
Mechanical Engineer
Sunpower Incorporated
Athens, Ohio
--

http://engineeringliberty.wordpress.com

 

[georg2976]

Thanks, but I need help in ANSYS program. I forgot to put in subject.

 

[flash3780]

What do you want to know about Ansys? Are you planning on superimposing the results of linear analyses as the author of the paper did?

I don't have a canned answer for a beam with a crack problem; the non-linearity of the opening and closing of the crack cannot be captured with a simple linear modal analysis. You'll have to use a more complex approach: Perhaps you could use a similar approach to that which is discussed in the paper above?

//signed//
Christopher K. Hubley
Mechanical Engineer
Sunpower Incorporated
Athens, Ohio
--

http://engineeringliberty.wordpress.com