Modal Analysis of a tapered beam
Submitted by shiva masana on Fri, 2009-06-19 18:30.
Hello everyone
I need modeshapes for a tapered beam, so I am using Ansys. By going through the tutorials I found that a beam can be modeled by creating a line and meshing it using Beam elements and assigning real constants. How can I use the beam elements for a tapered beam where the real constants are not constant. I tried to use tapered beam element but is of no use as it the created all elements of same real constants creating a profile similar to a hack saw.
Can anyone please help me how to mesh a tapered beam.
Awaiting the reply....
Shiva Masana
tapered beam stiffness matrix
Hi Shiva,
I have written a short paper that illustrates how to obtain the stiffness matrix for a tapered I-beam. The principles described in the paper may be used to describe any beam that has nonconstant cross-section as a function of position along the axis of the beam. Using this method you may numerically calculate the stiffness matrix of a tapered beam. Then construct a mass matrix and finally find eigenvalues and modeshapes by the standard techniques.
The method I explain is not usually carefully explained in matrix structural analysis books or journal articles. I have references at the end of the paper where bits and pieces of this method are explained. But, primarily I learned this in graduate school.
This would require you to program the technique in something like matlab.
You may find the paper at the following location: http://people.wallawalla.edu/~louie.yaw/structuralanalysis/taperframe.pd...
I hope this helps.
regards,
Louie
ANSYS Procedure for Tapered Beam
Dear Shiva
You can use BEAM elements by imposing different values of moment of inertia in each descritized cross section.
You may want to write a Macro in APDL (Ansys Parametric Design Language) and impose different real constants to each elmement using (*Do, *ENDDO) commands.
In this way, the geometry is the same and you can not distinguish it in ANSYS GUI but the tapered beam is considered in ANSYS calculations.
Best Regards,
******************************************
Ahmad Rafsanjani Abbasi
Graduate Student School of Mechanical Engineering
Acoustics Research Laboratory
Iran University of Science and Technology
Narmak 16844, Tehran, Iran
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Tapered Beam
Hi Shiva,
U go through Verification Manual34 (VM34) in ansys help. Ansys script is also given there for that example using different beam elements. If u still dont get mail me. thechenna123@gmail.com.