ASSIGNMENT-5
comparing the base setup simulation results and differant kinematic condition simulation results
OBJECTIVE:
The main objective of Assignment-5 is to create a 2D meshing on the Bumper and to connect the crash box with rear bumper by using connectors.
The another main objective of this assignment is to create different types of Interfaces, and assigning recommended values to the interfaces, and
comparing the base setup simulation results and different kinematic condition simulation results. And also to remove and add the notches to the given
model based upon the respected challenges.
The following are the various challenges that we have to perform in this assignment:
1. To Create the mesh for bumper assembly, and mesh size should be 6mm.
2. To Run the crash tube model as it is.
3. To Change the Inacti=6 and run.
4. To Create the type 11 contact and run.
5. To Remove both notches and to remove boundary condition on rigid body node then run.
6. To Create a new notch in the middle ,select the whole section and run.
7. To Create a new notch with nodes only from opposing 2 faces and run.
Case set up and Execution:
1. To Create the mesh for bumper assembly, and mesh size should be 6mm.
Step-1:
Intially open the hyperworks and click on the file - open - model and click on the bumper file.
FIG:BUMPER SYSTEM
Step-2:
After importing the model perform the meshing operation on the given model with a mesh size of 6mm.
FIG: BUMPER MESHING
Step-3:
Now we have create a connection between the crash box and rear bumper. So go to connectors - seam and provide the neccessary values.
we have to connect the crash box and rear bumper, so as to give accurate result when we perform the analysis. There are different types of connections are available, apart from this we have choosen seam weld which is used to connect the two different materials. The below diagram shows the seam connection between the crash box and rear bumper.
FIG: BUMPER CONNECTIONS
2. To Run the crash tube model as it is.
In this assignment actually we have focusing on the interfaces so let we discuss about the interfaces based upon their involvement in this assignment.
In this case actually the model is connected with type7 interface.
Interface:
Contacts are defined based on the application. For eg, if user is expecting an edge to edge contact Type 11 will be used.Type 2 interface is a tied interface that kinematically connects a set of slave nodes to a master surface.and thus it will not allow relative motion between the parts. If user expects a relative or sliding motion between parts Type 7 interface should be used, which is a multi-usage impact interface, modeling contact between a master surface and a group of slave nodes.
Interface Type 7: Nodes to Surface Contact:
Interface type 7 is a general-purpose interface and can simulate all types of impact between a set of nodes and a master surface.
1. Automatic node to surface contact interface using penalty method with variable stiffness.
2. A gap is defined around the master segment and the slave nodes.
3. The contact gap can be constant or variable.
step-1:
Importing the model.
Open hyperworks and select inport solver deck and import the model.
FIG: IMPORTING THE MODEL
Step-2: In order to create the THPART we have to click on the output Blocks and create the TH PART , in entity id instead of nodes keep components and select all four components and click on ok. Then the TH part is created.
step-3:
Now run the model as it is without changing any values in the interface card.
Important Interface Parameters:
Igap = Determines how the size of the gap is calculated.
Gapmin = Minimum gap for activation of interface.
Inacti = Action to take if initial penetrations exist.
Istf = Affects how the stiffness of the interface is calculated.
Iform = Friction formulation.
Stmin = Minimum stiffness to use in the interface.
Idel = Update For Deleted Elements Due to Failure.
So go to analysis - radioss - and save the file in the respected folder with respected name. by keeping the options
export = all
run = analysis
run number = 1
options = -nt 4
After running the file open the Crush_tube_0001 and check for the energy error and mass error.
ENERGY ERROR: Basically energy error must be negative and decreasing.The Error must be less than 15% at the end of computation, as per the condition. If the error is below 15% than the results could be acceptable.
So from the above figure, at the end of computation the energy error is -3.8% and mass error is 0.000 As per the condition the energy error is -3.8% which is below the 15% and the results could be acceptable for further simulation and ploting of graphs.
3. To Change the Inacti=6 and run.
In this case also same type7 contact is used only the change here is in interface card Inacti (Action to take if initial penetrations exist.) is changed to 6.
so select interface - type7 and change the Inacti as 6.
So go to analysis - radioss - and save the file in the respected folder with respected name. by keeping the options
export = all
run = analysis
run number = 1
options = -nt 4
After running the file open the Crush_tube_0001 and check for the energy error and mass error.
So from the above figure, at the end of computation the energy error is -5.7% and mass error is 0.000 As per the condition the energy error is -5.7% which is below the 15% and the results could be acceptable for further simulation and ploting of graphs.
4. To Create the type 11 contact and run.
This interface simulates impact between edge to Edge or lines. A line can be a beam or truss element or a shell edge or spring elements. Defined by identifying master and slave lines (edges). Impacts occur between a master and a slave line. A slave line can impact on one or more master lines. A line can belong to the master and the slave side. This allows self-impact.
FIG: TYPE 7 CONTACT FIG: TYPE 11 CONTACT
For creating type 11 contact either we can use hypermesh or hypercrash. hypermesh is generalised preprocessor, where as hypercrash is a specialised preprocessor.
In this case we are using hypercrash to create the type11 contact. so select applications in hypermesh and click on hypercrash and the software will be opened.
Assign the recommended values to the type11 contact.
After adding recommended values we have to open the model in hypermesh by using input solver deck, and we have to simulate by using radioss.
So go to analysis - radioss - and save the file in the respected folder with respected name. by keeping the options
export = all
run = analysis
run number = 1
options = -nt 4
After running the file open the Crush_tube_0001 and check for the energy error and mass error.
So from the above figure, at the end of computation the energy error is -4.0% and mass error is 0.000 As per the condition the energy error is -4.0% which is below the 15% and the results could be acceptable for further simulation and ploting of graphs.
5. To Remove both notches and to remove boundary condition on rigid body node then run.
In this case we have remove the notches and aslo to remove the boundary condition on rigid body node. So the notches are removed by using translate option or align option. and the boundary condition is removed by clicking on load collectors - rbody and off the translations and rotations.
by using align command we are removing both the notches.
now we can run the simulation.
So go to analysis - radioss - and save the file in the respected folder with respected name. by keeping the options
export = all
run = analysis
run number = 1
options = -nt 4
After running the file open the Crush_tube_0001 and check for the energy error and mass error.
So from the above figure, at the end of computation the energy error is -2.6% and mass error is 0.000 As per the condition the energy error is -2.6% which is below the 15% and the results could be acceptable for further simulation and ploting of graphs.
6. To Create a new notch in the middle ,select the whole section and run.
In this case we have to create a new notch at middle by using translate option or align option.
After creating a new notch at middle, we have to run the simulation.
So go to analysis - radioss - and save the file in the respected folder with respected name. by keeping the options
export = all
run = analysis
run number = 1
options = -nt 4
After running the file open the Crush_tube_0001 and check for the energy error and mass error.
So from the above figure, at the end of computation the energy error is -3.7% and mass error is 0.000 As per the condition the energy error is -3.7% which is below the 15% and the results could be acceptable for further simulation and ploting of graphs.
7. To Create a new notch with nodes only from opposing 2 faces and run.
In this case we are creating a notch with opposite faces by using nodes only in the align option, or by using translate option.
After creating a new notch at opposing faces, we have to run the simulation.
So go to analysis - radioss - and save the file in the respected folder with respected name. by keeping the options
export = all
run = analysis
run number = 1
options = -nt 4
After running the file open the Crush_tube_0001 and check for the energy error and mass error.
So from the above figure, at the end of computation the energy error is -3.5% and mass error is 0.000 As per the condition the energy error is -3.5% which is below the 15% and the results could be acceptable for further simulation and ploting of graphs.
ploting of graphs
2. To Run the crash tube model as it is.
In this challenge we did not changed any parameters. we just runned the crash tube as it is and various graphs are plotted and as shown below. Intially as the model is with type 7 contact, here the impact is taken between a set of nodes (slave) and the master surface. AS THE SLAVE NODES BELONGED TO MASTER SURFACE, THE INTERFACE CAN SIMULATE AUTO IMPACT ON THE MODEL WHICH WILL LEADS TO BUCKLING
FIG: CONTACT FORCES FIG: VON MISES STRESS
ENERGY PLOTS:
FIG: RIGID WALL FORCE FIG: CONTACT ENERGY
FIG:INTERNAL ENERGY FIG: HOUR GLASS AND TOTAL ENERGY
FIG:TH PART INTERNAL ENERGY FOR DIFFERENT SHELLS
3. To Change the Inacti=6 and run.
In this case we are changing tne Inacti=6 (Action to take if initial penetrations exist ) the number 6 indicates that the gap is variable with time (initial penetrations is computed).Intially as the model is with type 7 contact, here the impact is taken between a set of nodes (slave) and the master surface. AS THE SLAVE NODES BELONGED TO MASTER SURFACE, THE INTERFACE CAN SIMULATE AUTO IMPACT ON THE MODEL WHICH WILL LEADS TO BUCKLING.
FIG: CONTACT FORCES FIG: VON MISES STRESS
ENERGY PLOTS:
FIG: RIGID WALL FORCE FIG: CONTACT ENERGY
FIG:INTERNAL ENERGY FIG: HOUR GLASS AND TOTAL ENERGY
FIG:TH PART INTERNAL ENERGY FOR DIFFERENT SHELLS
4. To Create the type 11 contact and run.
In this challenge we have created a type11 contact and the Impacts occur between a master and a slave line. A slave line can impact on one or more master lines. A line can belong to the master and the slave side. This allows self-impact.
FIG: CONTACT FORCES FIG: VON MISES STRESS
FIG: RIGID WALL FORCE FIG: CONTACT ENERGY
FIG:INTERNAL ENERGY FIG: HOUR GLASS AND TOTAL ENERGY
FIG:TH PART INTERNAL ENERGY FOR DIFFERENT SHELLS
5. To Remove both notches and to remove boundary condition on rigid body node then run.
In this case we are removing all the notches and boundary condition, and various results are plotted.
FIG: CONTACT FORCES FIG: VON MISES STRESS
FIG: RIGID WALL FORCE FIG: CONTACT ENERGY
FIG:INTERNAL ENERGY FIG: HOUR GLASS AND TOTAL ENERGY
FIG:TH PART INTERNAL ENERGY FOR DIFFERENT SHELLS
6. To Create a new notch in the middle ,select the whole section and run.
FIG: CONTACT FORCES FIG: VON MISES STRESS
FIG: RIGID WALL FORCE FIG: CONTACT ENERGY
FIG:INTERNAL ENERGY FIG: HOUR GLASS AND TOTAL ENERGY
FIG:TH PART INTERNAL ENERGY FOR DIFFERENT SHELLS
7. To Create a new notch with nodes only from opposing 2 faces and run.
FIG: CONTACT FORCES FIG: VON MISES STRESS
FIG: RIGID WALL FORCE FIG: CONTACT ENERGY
FIG:INTERNAL ENERGY FIG: HOUR GLASS AND TOTAL ENERGY
FIG:TH PART INTERNAL ENERGY FOR DIFFERENT SHELLS
RESULT: COMPARISM OF ALL CASES.
In the above graph it clearly shows that there is a mass error remains same for all the cases, as well as hour glass energy remains constant in all the cases, and the minimum contact energy is zero and it is at 765 node in all cases as well as the mininum von meses stress is also zero and it is also at same node 765.and the unit system here we followed is mm, kg, ms.
CONCLUSION:
In this assignment what we have learnt is, how to create a connectors between the two components and also learnt how to create a interface to a component as well as how to create a notches in a component.
In this asssignment we have learnt about two types of interfaces. type 7 interface is a node to surface contact which will simulate due to auto impact and it gives good accuracy.
where as type 11 interface is a edge to edge contact which allows self impact.
There is a change in the internal energy and it is due to different types of interfaces, their recommended parameters and as well as due to notch position on the component.
THE NOTCH EFFECTS THE RIGID WALL FORCES . IN THE ABOVE CASES WE CAN SEE THAT THE RIGID WALL FORCES WILL BE SOME WHAT HIGH AND WHEN THERE IS NO NOTCHES IN THAT CASE THE FORCE WILL BE MINIMUM (1200) WHEN COMPARED TO OTHER CASES. AS WELL AS IN THE LAST CASE ALSO THE FORCE WILL BE LESS.
FINALLY WHAT WE CONCLUDE IS THE THAT THE SHELLS WHICH ARE NEARER TO THE RIGID WALL WE HAVE LESS INTERNAL ENERGY WHERE AS THE SHELLS WHICH ARE AWAY FROM THE RIGID WALL WE HAVE MORE INTERNAL ENERGY.
LINK: https://drive.google.com/open?id=1klGOrCru7ijMldvrXKPjWiGlw7zr0wVi