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PLOT OF LOAD AND DEFLECTION

PLOT OF LOAD AND DEFLECTION

PLOT OF LOAD AND DEFLECTION

(OP)
HELLO,
I HAVE DONE THE NON LINEAR BUCKLING ANALYSIS OF A BEAM. WHEN I PLOT LOAD - DEFLECTION CURVE ITS SHOWING A LINEAR GRAPH WHICH SHOULD NOT BE SO.
PLEASE SUGGEST ME HOW CAN I GET THE NON LINEAR PLOT.

RE: PLOT OF LOAD AND DEFLECTION

Was the analysis completed or it stopped before reaching full load ? What is the maximum registered load value ? It seems that only linear response before buckling was captured and it stopped when critical load was reached. Maybe more stabilization will help. Or you can increase imperfection scale.

RE: PLOT OF LOAD AND DEFLECTION

In the upgeom command make sure that your factor creates the desired imperfection (you should be able to look a the nodes to see that they have the imperfection). Secondly I would use displacement control to drive the analysis as it is easier to get convergence on. So instead of a force use an enforced displacement if possible.

As per previous use stabilisation (STABILIZE is the command can be set up also from /SOLU in Ansys) in ansys it is much better than ARCLEN.

Finally make sure you push past its limit load to see instability/collapse and make sure that you included BISO for plasticity for say steel.

Obviously the results are greatly influenced by the imperfection which say in steel design of buildings is given by the code (e.g., EC3). So make sure which imperfection to use and why it needs to be applied (say due to manufacturing)

RE: PLOT OF LOAD AND DEFLECTION

Is the curve obtained for one node (which one) ? How does the global deformation look like ?

This horizontal part of the curve means that displacements increase without change in load (neutral equilibrium path). For me it indicates that even though this approach shows correct buckling load, it can’t predict postbuckling behavior correctly. To obtain better results I advise you to follow Erik’s suggestions. Especially in terms of the use of displacement instead of load control and adding plasticity and stabilization.

RE: PLOT OF LOAD AND DEFLECTION

(OP)
HOW TO PLOT LOAD DEFLECTION CURVE.

RE: PLOT OF LOAD AND DEFLECTION

please learn to turn "CAPS LOCK" off … we don't like being shouted at.

What code are you using ? ANSYS ??

another day in paradise, or is paradise one day closer ?

RE: PLOT OF LOAD AND DEFLECTION

(OP)
sorry rb1957
I am using ANSYS APDL, From post-processing I have the options of plotting the curve between node displacement and time. But I need a curve between displacement and load.
By the way who told u I was shouting at you.

RE: PLOT OF LOAD AND DEFLECTION

"By the way who told u I was shouting at you." … that's the commonly understood interpretation of all caps text.

if you can only get displacement vs time, do you have a fixed relationship between load vs time ? then you can plot displacement vs load.

but then that may be a different interpretation of your graph. if your loading is a step function (100% load applied at time = 0), then the graph shows that the deflection increases to some steady state ?

another day in paradise, or is paradise one day closer ?

RE: PLOT OF LOAD AND DEFLECTION

(OP)
Ok thank you

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