[XANSYS] [STRUC] [WB] [MECHANICAL] Non- Linear Buckling Anal

[saroj.kumar.jha]

Hi Vinod,

As I remember your model and applied load, Your model is quite robust to applied load. You must be getting very high buckling load factor. If I correctly remember it was about 6500 for unit load. If you want to see the collapse of structure then you apply the buckling load factor X ( load in linear buckling analysis) during non linear analysis. Your system will surely collapse due to buckling in non linear buckling analysis before the collapse load suggested by linear buckling analysis. The reason is when we apply structural and material non linearity to system tends to move towards the unstable equilibrium rapidly which is not in the case in linear buckling , as above said non linearities are absent in linear buckling analysis. You will find that collapse load is lesser in comparision to collapse load suggested by linear buckling analysis. And hope fully you will get a nice cusp in your load vs displacement curve.

Regards
Saroj Jha
Engineer, CRVV
ITER-India

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From: vinod kumar ramamurthy
Sent: 10-08-2015 PM 08:51
To: xansys@xansys.org
Subject: [Xansys] [XANSYS] [STRUC] [WB] [MECHANICAL] Non- Linear Buckling Analysis


Vinod Kumar Ramamurthy
Bauhaus-Universität Weimar(NHRE)
vinod.kumar.ramamurthy@uni-weimar.de
www.uni-weimar.de



Dear All,

I had done the non linear analysis for a steel member of IPE section.

I first did my linear buckling analysis and based on the shape mode
results from that analysis I created a deformed geometry for
Non-Linear buckling analysis using the UPGEOM command.

I have also included the material non-linearity!!!

But to get the collapse load for the model, I tried to plot a graph by
establishing a relationship between the remote displacement and the
force reaction.

What I am getting is a Linearly plotted graph till the end time step
i.e., upto 1 sec.

i.e my reaction force keeps on increasing till the end!!! I am now a
bit confused whether my results are right!!!


can anyone help me how to get the correct way of obtaining the right results.

ANSYS v140.


Regards

Vinod Kumar Ramamurthy
Bauhaus-Universität Weimar(NHRE)
vinod.kumar.ramamurthy@uni-weimar.de
www.uni-weimar.de




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[vinod.kumar.ramamurthy]

Dear Saroj Jha

Like you said, I ran the analysis. You are correct. i got the graph
with that cusp point and also the collapse load difference from both
the analysis.

thank you so much. if any i will post for your help in future.


Mit Freundlich Grußen

Vinod Kumar Ramamurthy
Bauhaus-Universität Weimar(NHRE)
vinod.kumar.ramamurthy@uni-weimar.de
www.uni-weimar.de



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_________________
Vinod Kumar Ramamurthy
Bauhaus Universität - Weimar, Germany

[saroj.kumar.jha]

Thanks Vinod. Its good to hear that your problem is solved. Surely, I will post for help or will contact you by your email If need something.

Regards
Saroj Jha
Engineer, CRVV
ITER-India


From: "vinod kumar ramamurthy" <vinod.kumar.ramamurthy@uni-weimar.de>
To: "ANSYS User Discussion List" <xansys@xansys.org>
Sent: Tuesday, August 11, 2015 3:14:35 PM
Subject: Re: [Xansys] [XANSYS] [STRUC] [WB] [MECHANICAL] Non- Linear Buckling Analysis

Dear Saroj Jha

Like you said, I ran the analysis. You are correct. i got the graph
with that cusp point and also the collapse load difference from both
the analysis.

thank you so much. if any i will post for your help in future.


Mit Freundlich Grußen

Vinod Kumar Ramamurthy
Bauhaus-Universität Weimar(NHRE)
vinod.kumar.ramamurthy@uni-weimar.de
www.uni-weimar.de



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[vinod.kumar.ramamurthy]

Dear Saroj Jha

I would like to know about the behavior of a beam element model for the non-linear buckling analysis.

Like I told you in my earlier posts, I am dealing with the analysis of beam, shell and volume element for a IPE 300 member.

With your shared knowledge I was able to do the analysis and get the non-linear results curve graph in the non-linear buckling analysis for the shell and volume element.

But for beam element whatever load from the linear analysis's theoretical load calculation, which I apply it in non-linear buckling analysis I only get a linear curve for the force reaction and displacement plot.

Is that due to, the beam element can only give a global buckling unlike the other shell and volume element where we get a the local buckling ???

Or is it possible to achieve a local buckling in a beam element?? so that I could get results like in shell and volume element for comparison. !!!
_________________
Vinod Kumar Ramamurthy
Bauhaus Universität - Weimar, Germany