Assignment 4 Compare 7 cases as discussed in the slides
Aim: Compare and analyze 7 cases of rupture plate with different material properties and base on result finalized best case.
Material used for rupture plate:
1) Aluminum
Young Modulus E: 71000 N/mm^2
Poisson’s Ratio Nu: 0.33
Yield Stress SIGY: 290 N/mm^2
Case 1: Law 2_epsmax_failure
Import given file FAILURE_JOHNSON_0000.rad from solver deck. Verify below recommended shell property.
After running simulation below value got from FAILURE_JOHNSON_0001.out file.
Von mises stress contour plot
Max. Von mises Stress = 287.6 Mpa at node 3575.
Element get deleted. Since we set EPS_p_max = .151 means material will deleted when plastic strain energy reaches 15% of total strain energy.
Energy plot vs Time
Max Internal and Total energy= 27500 J
Kinetic Energy = 0
Internal and total energy increases vs time. Kinetic Energy remains almost zero.
As punch is moving and plate is stationary, hence K.E. zero.
Plate start resisting to punch as force increase with time, hence internal and total energy increase with time.
Case 2: Law 2_epsmax_crack
Changed properties of FAIL_JOHNSON card to Ifail_sh=1, Dadv =1 and Ixfem=1.
After running simulation below value got from FAILURE_JOHNSON_0001.out file.
Von mises stress contour plot
Max. Von mises Stress = 294 Mpa at node 4380.
In this case also element get deleted. Since we set EPS_p_max = .151 means material will deleted when plastic strain energy reaches 15% of total strain energy. Because of Ixfem = 1 element not scattered similar to case 1. Stress develop in this case is little more than previous case.
Energy plot vs Time
Max Internal and Total energy= 31000 J
Kinetic Energy = 0
Internal energy develop in this case is more than case 1. Behavior of graph is similar to case 1.
Case 3: Law 2_epsmax_nofail
In this case deleted FAIL_JOHNSON card and run the model.
After running simulation below value got from FAILURE_JOHNSON_0001.out file
Von mises stress contour plot
Max. Von mises Stress = 270.5 Mpa at node 3812.
In this case also elements get deleted. We are not defining failure mode because we don’t have failure card. In this case Ixfem value set to zero by default. Stress develop in this case is little less than case 1.
Energy plot vs Time
Max Internal and Total energy= 27500 J
Kinetic Energy = 0
Behavior of this graph is almost similar to case 1.
Case 4: Law 2
In this case kept value of EPS_p_max = 1 E^31 and run the model.
After running simulation below value got from FAILURE_JOHNSON_0001.out file
Von mises stress contour plot
Max. Von mises Stress = 424.7 Mpa at node 3984.
In this case elements are not cracked or deleted. Because strain value in rupture plate is less than default value of EPS_p_max = 1*E^31. Due to element not get deleted, resistance of plate increases hence stress developed is larger.
Energy plot vs Time
Max Internal and Total energy=65000 J
Kinetic Energy = 0
Internal energy generated in this case is larger than larger than case 1,2 and 3. In previous cases elements get cracked or deleted hence less internal energy developed. But in this case resistance by plate is more because elements not cracked or deleted hence more internal energy developed.
Case 5: Law 1_elastic
Convert material model to LAW 1 with same density, Young Modulus (E) and poission’s ratio (nu).
After running simulation below value got from FAILURE_JOHNSON_0001.out file
Von mises stress contour plot
Max. Von mises Stress = 10860 Mpa at node 3688.
In this case higher stress generated because plate behave like elastic manner. In plate no crack or material deleted, because there was no EPS_p_max value in law 1.
Energy plot vs Time
Max Internal and Total energy= 850000J
Kinetic Energy = 0
Due to elastic nature of material internal energy generated is higher.
Case 6: Law 36 elasto-plastic
Select M36_PLAS_TAB for law 36 elasto-plastic. Keep same value as previous for same density, Young Modulus (E) and poission’s ratio (nu). Below value set for M36_PLAS_TAB card image.
In N_funct below data use to generate curve.
After running simulation below value got from LAW27_0001.out file
Von mises stress contour plot
Max. Von mises Stress = 871.9 Mpa at node 4006.
Element in plate deleted because plastic strain in plate crosses EPS_p_max value.
Energy plot vs Time
Max Internal and Total energy= 45000 J
Kinetic Energy = Almost 0
Internal and total energy increases vs time. Kinetic Energy remains almost zero.
Before element start deleting K.E zero and Internal energy increases with fast rate.
After element start deleting K.E. increases slightly and Internal energy increases with slow rate.
Case 7: Law 27
Open model LAW_0000.rad and use below material card and shell property.
After running simulation below value got from LAW27_0001.out file
Von mises stress contour plot
Max. Von mises Stress = 277.2 Mpa at node 3820.
LAW27 combine isotropic Johnson-cook material and orthotropic brittle failure model. In this case element get cracked not deleted.
Energy plot vs Time
Max Internal and Total energy= 40000 J
Kinetic Energy = 0
Internal and total energy increases vs time. Kinetic Energy remains zero.
As punch is moving and plate is stationary, hence K.E. zero.
As force increase with time plate start resisting punching, hence internal and totaling energy increase with time.
Comparison and Conclusion
- Element get cracked or deleted based on EPS_p_max value.
- If element get deleted or cracked then stress and internal energy developed is less compare to element not deleted or cracked.
- Law1_elastic material card generate max stress and internal energy, because there was no element deleted or cracked.
- Selection of material card based on its application.