[Abaqus] Strange deformation of Eigenvalue Buckling

DoubleCNg · April 3, 2020, 13:47

Hello Guys,
I'm currently using Abaqus to run a simulation for Eigenvalue Buckling. The model I created was Discontinuous random oriented fibre composite, I used shell element to create a set of strands and then assembly to become combined strand and then created a solid matrix. Then, I used embedded element to combine the combined strand and composite. The buckling setup was Pin-Pin. I constraint one end with Pinned fixed, another end I defined a Multiple Point Constraint Pinned and applied a concentrated load on it (-1N).

After I ran the analysis, the result did not show a Pin-Pin buckling deformation, instead, it showed Fixed-Free buckling deformation. I had attached the image, please have a look.

I manually calculated the Pcr Theoretical Buckling Load, the load is quite similar with the Eigenvalue shown in Abaqus FEA result. I couldn't find any paper that says this issue or explanation in Abaqus Help Manual. Can anyone know what happens? Please Help Me. Thank You.

Regards,
DoubleCNg

Untitled 1.png

karachun · April 26, 2020, 16:33

What element type and constraints you use?

DoubleCNg · April 29, 2020, 00:34

Quote:

Originally Posted by karachun

What element type and constraints you use?

Hi, I used element C3D8R for the homogenous part (host) and S4R for shell part(embedded). Constraints is Pinned.

karachun · April 29, 2020, 02:23

If you apply pinned constraint to solid elements (C3D8R) then you actualy fix them, because you apply constraints to two rows of nodes. Try to model whole part only with plate elements.

April 3, 2020, 13:47	[Abaqus] Strange deformation of Eigenvalue Buckling	#1
DoubleCNg New Member Join Date: Apr 2020 Posts: 2 Rep Power: 0	Hello Guys, I'm currently using Abaqus to run a simulation for Eigenvalue Buckling. The model I created was Discontinuous random oriented fibre composite, I used shell element to create a set of strands and then assembly to become combined strand and then created a solid matrix. Then, I used embedded element to combine the combined strand and composite. The buckling setup was Pin-Pin. I constraint one end with Pinned fixed, another end I defined a Multiple Point Constraint Pinned and applied a concentrated load on it (-1N). After I ran the analysis, the result did not show a Pin-Pin buckling deformation, instead, it showed Fixed-Free buckling deformation. I had attached the image, please have a look. I manually calculated the Pcr Theoretical Buckling Load, the load is quite similar with the Eigenvalue shown in Abaqus FEA result. I couldn't find any paper that says this issue or explanation in Abaqus Help Manual. Can anyone know what happens? Please Help Me. Thank You. Regards, DoubleCNg Untitled 1.png

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April 26, 2020, 16:33		#2
karachun Senior Member Join Date: Nov 2015 Posts: 244 Rep Power: 11	What element type and constraints you use?

April 29, 2020, 02:23		#4
karachun Senior Member Join Date: Nov 2015 Posts: 244 Rep Power: 11	If you apply pinned constraint to solid elements (C3D8R) then you actualy fix them, because you apply constraints to two rows of nodes. Try to model whole part only with plate elements.