Assignment 7

Objective :
To perform a crash test using the given model of car and determine the varies forces acting on cross section of the car during the side impact of the car .

Neon side crash -BIW

• Check unit system and either follow [Mg mm s] or [Kg mm ms].
• Create appropriate interface ,friction 0.2 and recommended parameters.
• Make sure of no penetration and intersections.
• Create rigid wall with friction 0.1 as per referance model
• Compare the model weight with the referance model and use added masses to reach target weight 700kg while getting CG about the required range.
• Initial velocity as shown in picture.
• Use model checker to ensure good quality.
• Timestep :0.5 to 0.1 microseconds.
• Run 80ms.
• Output requests:

Sectional force in the cross member.

• Intrusion at B pillar,hinge pillar and fuel tank region.Provide recommendation on what can help to reduce Fuel tank intrusion.
• Peak velocity of inner node of the door.

Given model:

Procedure:

1.Check unit system and either follow [Mg mm s] or [Kg mm ms].

Unit system is set as [Kg mm ms]

2.Create appropriate interface ,friction 0.2 and recommended parameters.

A type 7 contact interface is created with recommended properties.
[Istf]stiffness definition = 4
[Igap]Gap/element = 2
[Idel]stiffness delete =2
[fric]friction =0.2
[Gapmin]MIn gap = 5
[Inacti]stiffness deactive =6
[Iform]Friction penalty formulation =2

3.Make sure of no penetration and intersections.

Penetration and intersections was checked through Tools > penetration check and make sure that no penetration and intersections was involved.

4.Create rigid wall with friction 0.1 as per referance model.

5.Compare the model weight with the referance model and use added masses to reach target weight 700kg while getting CG about the required range.

The intially weight of the model was 166.3kg.Since our target weight was 700kg, So we have added some mass to attain 700kg for that 700-166.3=533.7kg we have to added it in model. Maintaince the position of the CG point in the middle of the vehicle ..

6.Initial velocity 35 mph.

The velocity of model should be in mm/ms.
So mph is converted into mm/ms.
1mph = 0.447 mm/ms
35mph = 35 x 0.477 = 15.64 mm/ms.

7.Timestep :0.5 to 0.1 microseconds.

8.Run 80ms.

Intrusion at B pillar,hinge pillar and fuel tank region.Provide recommendation on what can help to reduce Fuel tank intrusion.

Sectional forces:

After completion of every thing , we can move to model checker to check how many error was there . The model checker can run in Hypercrash and we can correct these error in Hypermesh , because hypercrash could carry out only 10000 nodes but our model is consists of around 90000 plus nodes ,so cannot export in Hypercrash.

After stimulation completes we have look into open neon_side_reduced_0001.rad in note pad and check energy errror and mass error using default value , energy error and mass error had been highlighted using sketch.

Energy error in the basic stimulation case is -1.0%
Energy error is accepted upto 15%
Mass error =0.1152E-01

Next move to hyperview For run the stimulation select h3d file - open,
Click contour - Resultant type as displacement - Apply

Maximum displacement at node 190233 is 1.445E+03
Minimum displacement at node 346252 is 0.000E+00

Instead of displacement select - von mises - apply.(it will shows different stress of each and every element)

Maximum vonmises peak is 4.420E-01 in node 121240
Minimum value is 0.000E+00 in node as 346252.

Next move to hyper graph 2D ,For run the graph select To1 file - open
plot the graph for Global variable as Internal energy and kinetic energy,hoursglass energy, total energy,contact energy.

According to the graph ,internal energy starts from zero and where as kinetic energy starts from the peak point because initial velocity applied,once the stimulation runs the neon side model hits the pole,its gets deformed, so kinetic energy decreases due to the resistance placed by the pole .while the internal energy is increased due to energy placed inner side of vehicle, when its hit the hole gets deformed.the Hourglass energy is placed zero level, whereas the total rotational energy is placed at the pick of the graph.

Crosstional Forces:

According to the graph, both the cross sectional are placed in B pillar,so the force distribution are quit similar in both of the crosssection .in 2st crosssectional the maximum force examined as 1.8KN at 78ms, where as second crosssection is 5.8Kn at 50ms,in these 1nd force recieves less forces , maximum force recieved on second crossectional force.

Peak velocity

The peak velocity is created at passenger side door at nodal point 337773, to calculate the displacement produce while its gets crashed on the side pole.Maximum velocity recieved at 400 at time 78ms. After impact it decreases to zero and then it increases as it intrudes in the y-direction. Peak velocity is an important because the driver compartment also has the same velocity. So the driver will also experience the same velocity while the impact on the side crash.

Intrusion

Intrusion is used to find out the deformation occurs on while the car hits the pole on its side,in the above we have plotted displacement vs time graph.We have plotted three Intrusions on the B pillar,hinge pillar and fuel tank region at 123279,123296 and 12321.each intrusion are producing various displacement.

Symmary:

• Max force for a cross-section in cross member-1 = 1.6 KN
• Max force for a cross-section in cross member-2 = 6 KN
• Displacement of hinge pillar node 123321 =654 mm
• Displacement of B- pillar node 123279 =235 mm
• Displacement of Fuel Tank node 123296 =336 mm
• Peak Velocity of node 337773 =400mph at 78ms
• Maximum VonMises Stress = 4.420E-01

Conclusion:

• Energy is -1.00%
• Mass Error is 0.1153E-01
• In this Assignment i had learned how to create the set sectional forces in various cross sectional force placed on the pillar , and how to create intrusion node measurement.
• In these side crash Assignment i had created 2 cross sectional forces, In these the maximum forces acts on the second crossection placed on the pillar .The least force acts first crossection placed on the pillar.
• The intrusion placed in B pillar,hinge pillar and fuel tank region at 123279,123296 and 12321 to aviod minimizes the level of risk .
• which can reduce the intrusion of fuel tank and so driver, which can decrease the intrusion and damage.
• The center of gravity is plays an important role in the side crash analysis.It is used to determine the strength and stability of the structure,here the CG point is placed middle of the car
• More forces are acting on the mid portion of the car, more deformation in the middle portion.
• Internal energy starts from zero and where as kinetic energy starts from the peak point because initial velocity applied,once the stimulation runs the neon side model hits the pole,its gets deformed
• so kinetic energy decreases due to the resistance placed by the pole .while the internal energy is increased due to energy placed inner side of vehicle, when its hit the hole gets deformed.the Hourglass energy is placed zero level, whereas the total rotational energy is placed at the pick of the graph.The mass error , energy error are under the acceptable values.
• Due to high impact forces, side of the vehicle gets damages more.