Week - 10 Hyperelastic Material Models
Hyper Elastic Material: General elastic material behaves elastically around 0.02 to 0.2% of strain but the Hyperelastic materials behave elatically around 500% of strain. These will behave lineat for some part and non-linealy for the remaining part of elasticity.
AIM: To model the Dog bone specimen using the Hyperelastic material model and get the values of Mooney Rivlin constants and odgen model and compare the obtained stress-strain curves for all the models.
PROCEDURE:
- From the figure shown in the image get the data to the excel.
- Then this data is loaded to the curve in the LS_DYNA as shown in the figure.
- Then assign this curve to the Material Rubber (MAT_077) by giving N=1,2,3 based on the accuracy.
- For the Dog_bone Specimen we need to give the boundary conditions by fixing in X and Z direction at the left most end nodes and fixing Y direction left end mid node.
- The Displacement loading should be given at the right most end nodes of the specimen as shown in the Figure.
- Use the Control Card for specifying the termination time as 5 seconds.
- Specify the Deliverables with DT as 0.1 seconds.
Mooney Rivlin Material(MAT_077): Using the Material Card MAT_077 and the engineering stress and strain data we need to find out the Mooney Rivelin Constants by varying N=1,2,3. Using the d3hsp file the we can get the constant values and we can also get the stretch ratio vs true strain data, this we can compare with the experimental data and choose the best parameters.
N=1
N=2
N=3
- There is no much deviation with all the N values we can choose any N value with respect to the Mooney Rivelin Material model.
Odgen Material Model(MAT_077_O): The same procedure is repeated for this material model as well and check the constants and the fitted curves with respect to the experimental data.
N=1
N=2
N=3
CONCLUSIONS:
- For the mooney rivelin model the curve fitting for all the N values is almost same and accurate.
- For the Odgen Material model the curve fitting with Experimental Data for all the N values is same but accuarcy is bad.
RESULTS : The Modelling the Hyperelastic material model using the LS_DYNA material card MAT_077 and MAT_077_O for Dog bone Specimen is done.