Week - 10 Hyperelastic Material Models
AIM
Calculate Mooney Rivlin and Ogden material constants and compare the both using stress-strain data from a Dog bone specimen tensile test with 100 percent strain.
OBJECTIVE
- Plot data of given data.
- Create curve on Ls dyna.
- Create material of hyper elastic.
- Find Mooney Rivlin constants and Ogden material.
- Plot graph from extension and stress data.
Theory
Hyper elastic: The material which can be elastic upto 500% strain is known as Hyperelastic. Eg rubber,Foam, Adhesive etc.
Young’s Modulus of Hyper elastic material lies between 0.01 -100 Mpa.
Stretch = Final length/Original Length or Strain-1
Strain Energy: The energy stored by the material while deforming is known as Strain energy. Strain energy is usually defined per unit volume.
Strain Energy/ Volume = (Stress*Strain)/2
PROCEDURE
- Date imported in spreadsheet.
- Create curve
The data from the spreadsheet in inserted in the Ls dyna curve.
MODEL > KEYWORD > DEFINE> CURVE
- Material card
For hyper elastic material OGDEN material card is used.
MODEL > KEYWORD > MAT> OGDEN_RUBBER
Here N=1,2&3 is defined to get constants.
- Section
MODEL > KEYWORD > SECTION > SHELL
- Parts
MODEL > KEYWORD > PARTS
- Boundary conditions
SPC set is formed.
Prescribed motion set
- Termination
- Output
Binary D3 plot
Extended binary
- Save the file
- Run the program
- D3hsp file
In this file constants and stretch-stress is given.
Folder(Where simulation data is saved) > D3hsp
- Excel file
In this all the constants, stretch, stress is present and plotting an graph for comparison.
- Graph
- Simulation
CONCLUSION
From graph it is found that the Hyper elastic n=2,3,1 are very close to each other however Ogden 2&3 are close but Ogden 1 is closer to given data curve.