Week - 10 Hyperelastic Material Models

Objective:

Given the material data below, calculate the Mooney Rivlin and Ogden material constants and compare them both using stress-strain data from a Dogbone specimen tensile test with 100 percent strain. The given data is the engineering stress-strain in MPa/(mm/mm). The comparison should be shown from the d3hsp file and using simulation.

Procedure:

1. Take the given material data in excel and plot the stress-strain graph

2. Import the given Dogbone_specimen.k in LS DYNA Pre-Post
3. Define Curve in keyword manager using the Effective Stress and strain.

4. Define curve for displacement in keyword manager

5. Create a Material card assigning the values of casting iron and assign the curve defined.

6. Create Section Shell for the specimen assigning thickness of 2mm and ELFORM=2.

7. Edit the Part, assigning the material and section shell created.

8. Assign Boundary Conditions:

a) Constrain all the nodes of one end of the dog bone specimen in all directions except translational Y direction.

b) Constrain the mid nodes of both ends of the dog bone specimen in Y translation to restrict the slip during simulation.

9. Assign Displacement for the specimen onset of nodes on another side with the curve defined.

10. Add the following control cards
11. a) Control Implicit General – IMFLAG =1, DT0 = 0.01, IMFORM = 2.

b) Control Implicit Auto – IAUTO=1, ITEOPT =11, ITEWIN=5, DTMIN=0, DTMAX=0.

c) Control Implicit Solver – LSOLVR=6.

d)Control Termination – ENDTIM=1.

11. Add the following Database Cards

a) BINARY_D3PLOT with DT=0.01

b) DATABASE_EXTINCT_BINARY with STRFLG=1

c)DATABASE_ASCII with ELOUT, GLSTAT, MATSUM

12. Set ENDTIM as 1 ms in CONTROL – TERMINATION keyword card.
13. Check the keyword manager for any errors.

14. Save the Keyword file as in the new folder and run the keyword files in LS – Run.
15. Repeat the same with N=2,3 to get the constants from the d3hsp file.

Plot the graph from the values.

16. Now using the constants, perform the same simulation keeping N = 0 (Material Verification)

17. In the Fringe Component option, Select Von-mises stress for the contour plot and save the von-mises animation videos.

Effective Stress Plot

Effective Strain plot

Stress vs Strain Plot

Conclusion:

The graph we obtained from the simulation is almost identical to the graph given.

Learning Outcome:

Performing Tensile test based on the material curve given.