LEFM load displacements

[marcus.stephan.schulze]

Hi Lukasz,

I hope you enjoyed your christmas,

I just want to know how you got the load displacement curves for through LEFM so that I can compare them? I have the equation that you sent me which gives any value of nominal stress for the given depth, but I dont know how you got the load displacement curves.

Kind Regards,

Marcus

[Lukasz Kaczmraczyk]

Hello,

These are calculated by FE analysis. I give you at the same point files all results for LFEM. You will have to understand and process data there.

KInd regards,

Lukasz

[marcus.stephan.schulze]

Hi

How can I do this? 

Kind Regards, 

Marcus 

[Lukasz Kaczmraczyk]

Look into file make.gp, there is the answer.

set title "Size effect three point bending beam"

set ylabel "Nominal Strength (MPa)"

set xlabel "Deflection ({/Symbol m}m)"

plot [0:350] [0:7] \

'size_effect_4000' u 2:3 w l lw 4 lt 2 title '4000mm computed', \

'size_effect_4000' u 4:5 w l lw 4 lt 2 title '2000mm scaled from 4000mm', \

'size_effect_4000' u 6:7 w l lw 4 lt 2 title '1000mm scaled from 4000mm', \

'size_effect_4000' u 8:9 w l lw 4 lt 2 title '500mm scaled from 4000mm', \

'size_effect_4000' u 10:11 w l lw 4 lt 2 title '250mm scaled from 4000mm', \

'size_effect_4000' u 12:13 w l lw 4 lt 2 title '125 scaled from 4000mm', \

'size_effect_4000' u 14:15 w l lw 4 lt 2 title '62.5mm scaled from 4000mm', \

'gp62.5' u 2:3  w l lw 3 lt 7 title '62.5mm computed', \

'gp500' u 2:3  w l lw 3 lt 7 title '500mm computed', \

'strength_4000' u 1:2 w p lt 3 lw 2 title ''

pause -1

       

Results for different sizes, scaled from size 500mm are in file "size_effect_4000", look at displacements and stress in columns in pairs 1:2, 3:4, .. and so on. Calculated values are for size 62.5 mm and 500mm, and those are in files "gp62.5" and "gp500", respectively. 

Kind regards,

Lukasz

[marcus.stephan.schulze]

Hi Lukasz, 

Is it possible to get the compliance function from the FE results above? For larger values of D, the difference between the traction free crack and the traction free + cohesive crack becomes smaller and then this approximation will be acceptable? It would then be similar to what I did with the double cantilever beam - where the compliance function was estimated from LEFM, which in turn meant it was accurate for smaller values of Gf. 

Kind Regards, 

Marcus 

[marcus.stephan.schulze]

Also, what is the ratio of a/D for the a is the traction free notch where the split sideset is done? i cant find the length of the traction free notch in the mesh.

Kind Regards, 

Marcus 

[marcus.stephan.schulze]

Hi lukasz, 

how do I get access to the make.gp file?

Kind Regards 

Marcus 

[Lukasz Kaczmraczyk]

Hello,

Go to the directory where make.gp is located and run:

gnuplot make_gp

Note that you can open those files by yourself in excel, and process them.

Kind regards,

Lukasz