TensileTest

Tensile Test

Tested with CGX 2.19 / CCX 2.19

Tensile test of a 8x25mm steel bar. The yield curve is obtained from real test data and the simulated stress-strain curve is compared to the experimental one.

Using symmetry, the structure is reduced to one eight of the original one.

• Large displacements
• Plasticity
• The structure is parametrized using CGX valu due to it's simplicity
• Handover of load parameters to the CCX file
• Handover of parameters to the gnuplot file

File	Contents
pre.fbd	Pre-processing script for CGX (parametrized with valu commands)
post.fbd	Post-processing script for CGX (stress-strain curve and deformed plot)
sigeps.gnu	Gnuplot control script
Zug.inp	CCX input
test.py	Python script to run the full simulation

Preprocessing

> cgx -b pre.fbd

The geometry consists of a simple brick, representing an eighth of the total specimen. In order to induce necking in the symmetry plane, a small imperfection (Width reduction) is introduced.

The mesh is biased as to account for the localized deformation.

Parameter	Value	Meaning
lx	40	half of sample length in mm
ly	12.5	half of sample width in mm
lz	4	half of sample thickmess in mm
divx	40	mesh divisions in x-direction
divy	12	mesh divisions in y-direction
divz	6	mesh divisions in z-direction
biax	4	mesh bias in x-direction
maxeps	40	max engineering strain in %
imp	-0.05	imperfection (half of width change at the center in mm)
rimp	5	radius of influence of the imperfection in mm

Boundary conditions:

• ux = 0 at x = 0 (symmetry boundary)
• ux = maxeps/100*lx at x = lx (prescribed displacement)
• uy = 0 at y = 0 (symmetry boundary)
• uz = 0 at z = 0 (symmetry boundary)

Solving

> ccx Zug
> monitor.py Zug

The second command generates a convergence history plot of the solution.

Postprocessing

> cgx -b post.fbd

This creates a stress-strain curve and an expanded plot of the equivalent plastic strain.

You can generate the stress-strain curve separately using the commands:

> dat2txt.py Zug
> gnuplot sigeps.gnu