Stretch Ratio
OBJECTIVE:
The main objective of this simulation is to create a solid cube and to find how the simulation runs if we change the element formulations of the solid section as 1, -1, 2, -2 and to plot the uniaxial tension plot with the stress vs Stretch ratio plot.
CASE SETUP AND EXECUTION:
- Open LS Pre-Post
- Create a solid section (CUBE) of 10mm*1omm*10mm and the same has been meshed with the element size of 1mm
- Create 4 individual section cards with Element formulation as 1, -1, 2, -2
- Create Material Card and assign both the section and material to the part ID
- Simulate Tensile behaviour of the given model
- Fix one end using SPC Constraints and in the other end Prescribed motion set (Boundary card) has been created with the displacement node
- Control Termination has been set upto 0.1ms
- Binary plot has been set as 5e-4
- Run the simulation
- In Post processing, Under History tab, select an element to calculate the Von-Misses Stress and Effective Plastic Strain of the selected element and save the graph plot.
- Under X-Y section, Plot the Stress-Strain curve for the selected element.
- Follow the procedure for all the element formulations.
- STRETCH RATIO is calculated by (1 + Engineering Strain)
- Plot the Stress VS Stretch Ratio curve in excel and interpolate the results.
|
ELEMENT FORMULATION |
DESCRIPTION |
|
1 |
Constant Stress solid element type. Default |
|
-1 |
Fully integrated S/R solid intended for elements with poor aspect ratio, efficient formulation |
|
-2 |
Fully integrated S/R solid intended for elements with poor aspect ratio, accurate formulation |
|
2 |
Fully Integrated S/R solid. |
IMAGES AND GRAPH:
ELFORM 1
- Stretch ratio has been identified by (1+ Strain)
- The points have been taken from the stress-strain plot of the graph (taken from a element) and has been plotted
- As the stress increases, the stretch ratio increases.
ELFORM -1
- Stretch ratio has been identified by (1+ Strain)
- The points have been taken from the stress-strain plot of the graph (taken from a element) and has been plotted
- As the stress increases, the stretch ratio increases steadily
- Unlike Element formulation 1 , the curve increases too but not monotonically.
ELFORM 2
- Stretch ratio has been identified by (1+ Strain)
- The points have been taken from the stress-strain plot of the graph (taken from a element) and has been plotted
- As the stress increases, the stretch ratio increases steadily
- Unlike Element formulation -1 , the curve increases gradually one over the another.
ELFORM -2
- Stretch ratio has been identified by (1+ Strain)
- The points have been taken from the stress-strain plot of the graph (taken from a element) and has been plotted
- As the stress increases, the stretch ratio increases steadily
- Unlike Element formulation 2, the curve forms a parabolic shaped curve.
CONCLUSION AND RESULT:
- From the comparisons with the 4 element formulations of the sectional solid, elements fails with a negative volume incase of higher termination. So I preffered to run the simulation with 0.01ms with a time step of 5e-4 ms.
- The stress vs strain curve was plotted at the first and with the formula to calculate stretch curve, the stretch curve was calculated. The Stress vs Stretch Ratio curve was plotted for all the four element formulations.
The link for validation is
https://drive.google.com/open?id=1UYn0ah6XiMbBRYKTBlI8cDJz9j05_yaB