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[XANSYS] [STRUC] [WB] [MECHANICAL] Non- Linear Buckling Anal
 
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vinod.kumar.ramamurthy
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Joined: 24 Jun 2015
Posts: 10
Location: Weimar, Germany

PostPosted: Mon Aug 10, 2015 3:21 pm  Reply with quote

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




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Vinod Kumar Ramamurthy
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Martin Liddle
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Joined: 15 Aug 2008
Posts: 1274
Location: Chesterfield, UK

PostPosted: Mon Aug 10, 2015 3:30 pm  Reply with quote

On 10/08/2015 12:44, vinod kumar ramamurthy wrote:
Quote:
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.

The linear curve suggests the beam has not buckled. What load were you
applying (magnitude and direction)? What happens if you use a higher load?

--
Martin Liddle, Tynemouth Computer Services,
Chesterfield, Derbyshire, UK.
www.tynecomp.co.uk

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vinod.kumar.ramamurthy
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Joined: 24 Jun 2015
Posts: 10
Location: Weimar, Germany

PostPosted: Mon Aug 10, 2015 11:10 pm  Reply with quote

Dear Martin Liddle and Saroj Jha

I gave a unit load of -1 N in the x-component. For which i got a load
multiplier of 3.6675e+06.

Which the load factor multiplied by the applied loads in Linear
buckling I used it in non-linear buckling analysis like saroj jha
replied in the post.

I get an unconverged solution and a error comment" the solver engine
was unable to converge on a solution for the nonlinear problem as
constrained."



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



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saroj.kumar.jha
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Joined: 03 Jun 2015
Posts: 7

PostPosted: Tue Aug 11, 2015 8:13 am  Reply with quote

Dear Vinod,

Now you got the buckling collapse load. That point of non convergence in non linear analysis is your point of buckling. You can now plot the force reaction vs deformation and get the buckling collapse load. The cusp point in the above said plot is point of buckling and force at that point is buckling collapse load.


Regards
Saroj Jha
Engineer, CRVV
ITER India

Sent from my Windows Phone
From: vinod kumar ramamurthy
Sent: 11-08-2015 AM 04:39
To: ANSYS User Discussion List
Subject: Re: [Xansys] [XANSYS] [STRUC] [WB] [MECHANICAL] Non- Linear Buckling Analysis


Dear Martin Liddle and Saroj Jha

I gave a unit load of -1 N in the x-component. For which i got a load
multiplier of 3.6675e+06.

Which the load factor multiplied by the applied loads in Linear
buckling I used it in non-linear buckling analysis like saroj jha
replied in the post.

I get an unconverged solution and a error comment" the solver engine
was unable to converge on a solution for the nonlinear problem as
constrained."



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



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| Send administrative requests to xansys-mod@tynecomp.co.uk |
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saroj.kumar.jha
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Joined: 03 Jun 2015
Posts: 7

PostPosted: Tue Aug 11, 2015 8:14 am  Reply with quote

Continuation to my last post,
That non convergence is due to buckling collapse and so the error. This error and non convergence will always occur, if buckling collapse is there. Infact this non convergence is indication of buckling collapse.

Hope your problem is solved now. For more understanding on buckling failure mode , I would suggest to study ASME section VIII div 2 part 5. This gives good idea about the buckling failure mode and its assessment.

Have a nice day.

Regards
Saroj Jha
Engineer, CRVV
ITER India

Sent from my Windows Phone
From: vinod kumar ramamurthy
Sent: 11-08-2015 AM 04:39
To: ANSYS User Discussion List
Subject: Re: [Xansys] [XANSYS] [STRUC] [WB] [MECHANICAL] Non- Linear Buckling Analysis


Dear Martin Liddle and Saroj Jha

I gave a unit load of -1 N in the x-component. For which i got a load
multiplier of 3.6675e+06.

Which the load factor multiplied by the applied loads in Linear
buckling I used it in non-linear buckling analysis like saroj jha
replied in the post.

I get an unconverged solution and a error comment" the solver engine
was unable to converge on a solution for the nonlinear problem as
constrained."



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



+-------------------------------------------------------------+
| XANSYS web - www.xansys.org/forum |
| The Online Community for users of ANSYS, Inc. Software |
| Hosted by PADT - www.padtinc.com |
| Send administrative requests to xansys-mod@tynecomp.co.uk |
+-------------------------------------------------------------+

Email secured by Check Point
+-------------------------------------------------------------+
| XANSYS web - www.xansys.org/forum |
| The Online Community for users of ANSYS, Inc. Software |
| Hosted by PADT - www.padtinc.com |
| Send administrative requests to xansys-mod@tynecomp.co.uk |
+-------------------------------------------------------------+

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