Negative Total Energy????

[kooshaa]

Is it possible for total energy to be negative in abaqus simulation? For better understanding of my problem I attached the screen shot of the process.

http://files.engineering.com/getfil...4c3-47ab-b32a-6111f0b1b10a&file=Unbenannt.png

 

[kooshaa]

Can it be because I have compression?

 

[Dave442]

Can you plot the components of the total energy to see what is driving the negative value?

 

[kooshaa]

I plotted the components of the total energy. To my surprise there was no negative component!

here is the plot.

http://files.engineering.com/getfile.aspx?folder=65e32cde-22ed-41ef-9cdc-601a1f2d6fbe&file=1.png

 

[Dave442]

I think the plots you generated are for a single element. If you open your .odb and expand the contents under 'History Output' in the model tree you should be able to plot ETOTAL along with all of its components such as ALLIE, ALLKE, ALLSE etc. for the entire model. This should help figure out whats going on?

 

[kooshaa]

Dave442, I did what u said. Here is the energy components for the whole model.

http://files.engineering.com/getfile.aspx?folder=d03fc299-f68e-44cd-9683-ce8694429c43&file=graph.png

The three big components are: External work (ALLWK), Internal Energy (ALLIE) and Plastic dissipation (ALLPD). It seems that the big value of eternal work is driving the total energy to be negative. Is it ok to be negative? I mean can eternal energy get bigger than internal energy?