CRUSH BEAM

AIM :

• Create the mesh for bumper assembly,mesh size should be 6mm.

1. Run the crash tube model as it is.
2. Change the Inacti=6 and run.
3. Create the type 11 contact and run.
4. Remove both notches and remove boundary condition on rigid body node then run.
5. Create a new notch in the middle ,select the whole section and run.
6. Create a new notch with nodes only from opposing 2 faces and run.

OBJECTIVE :

Given crush tube file has contact interfaces we need to find how the crush tube file simulation is happening when we are changing the contact interfaces as type 7 and type 11 and also find the simulations for removing of notches and keeping of notches .

Interface is like a law that we are going to define which will tell the two mating components how they are suppose to ignore each other or suppose to collide each other

Interfaces are defined to model how parts are interacting when they come into contact with each other .

inacti------->action to take if initial penetration exists.

gapmin------->minimum gap for activation of interface.

type 7 interface is general purpose interface and we can simulate all types of impact between a set of nodes and master surfaces .

the contact gap can be constant or variable

interface timestep is computed to insure stability.

The stiffness is inversly proportional to timestep

if the stiffness is going to infinity and timestep will decrease

so,this decreasing of time step will through our simulation into problem.

so in CASE 1:

As it is with out changing any contact surfaces ran the simulation .and plotted the results as shown in the below figure .

For the cycle 82600 if we observe mass error 0 and error is -3.8%.

at 1400 kn force and time 25 sec internal energy is incraesing

CASE 2 :

For case 2 as per assaignement we need to change inacti =6 and run the simulation

the results are plotted below.

in order to set penetration inacti has been set to 6, If we run the simulation the crush tube will hit the rigid wall if we observe the contour plot we can get maximum and min contact forces .

and also if we observe the normal forces also increases due to collisions of the elements.

case 3:

In this case 3 type 11 contact has been craeted and run the simulation .

results are plotted below.

the internal eneregy increased and here in we kept the type 11 contact that means it will take edge to edge contact at 30 sec the internal energy is increased

the resultant tangential force is also increased and also change in enegry also observed from the graphs

resultant force increases and decreases during the simulation that means during the collison of elements

case:4

for this case 4 removed the notches by using F7 and also removed the boundary conditions and run the simulations.

results are plotted below

Here we removed the notches and run the simulation that means the crush tube will hit the wall with out any interruptions as compared to the previous simulations. here contact energy is very high as compared to the previous simulations .and here internal energy increases obviously,the contact energy is very high,

the error has been decreased to -0.4%

case :5

In case 5 craeted the new notch by using traslate option and F4 option and run the whole selected simulation.

results are plotted given below.

here we craeted the notch in middle due to this the internal energy increased and resultant normal force was high during the collision time total energy observed by the crush tube is little high.

the error has been decreased to -0.1%

case:6

in this case created the notches at the opposite faces and run the simulation

the results are plotted below .

in case 6 we created the extera notch at the rigid body side ,and if we observe the simulation and graphs we can observe hange in energy and the internal energy increases throuygh out the simulatiuon

the contact energy is also very high

created the mesh with element size of 6mm

https://drive.google.com/open?id=1TZIV6yNSh8ggNjLs5dYpIfye6otHY6KV

conclusion:

Run the simulations for all 6 cases by using two type of interfaces ,a nd plotted the results and observed the energy changes accordingly

mainly while having nothes and with out having and also with and with out having boundary conditions how the energy plots were changed