Project 5report

Venkata Sai Gopala Krishna vemuri
Ft6503@wayne.edu
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Project 5
Analysis of Dummy in Different Frontal Impacts
Venkata Sai Gopala Krishna Vemuri
Ft6503

Ft6503@wayne.edu
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Problem:
Abstract:A finite element (FE)model based ona2001 Ford Taurus passengersedan
was developed through the process of reverse engineering at the National Crash
Analysis Center (NCAC) of The George Washington University (GWU) under an
FHWA contract. This model was initially validated by comparing the simulation of
the NCAP frontal wall impact with actual data from NHTSA tests for a comparable
vehicle. Acceptable results ofthe initial validation led to the release of the FE model.
Subsequently, the model was periodically updated and enhanced with the inclusions
of the interior elements. Additional validation efforts were undertaken using data
available from other crashtests, including full frontal wall, offsetdeformable barrier,
moving deformable barrier, and offset rigid pole impacts. Simulation results
compared well to data from these tests to determine the validity of the enhanced
model. The capabilities of the model were also checked by damage consistency
comparisons for rigid wall, offset deformable barrier, and centerline pole impacts at
varying speeds. Thesimulations executed without error in these runs and the results
reflected the expected responses and consistency with varying parameters.
A) Frontal Impact with Infinite Rigid Wall
B) Frontal Impact with 25% Rigid Wall
C) Frontal Impact with 40% Rigid Wall
D) Compare and Analyze impact on Dummy with airbag and seat belt
and without airbag and seat belt.
E) Compare the Plots of Vonmisses Stresses, Pressureand Plastic
Strain, and also total energy.
F) Improvise the structure and suggest the best way to save the
Dummy after the impact.

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Model given:
Note: The given model doesn’t have airbag, seat, Dummy and Rigid Wall.
Software’s used: LS-Prepost, Hypermesh (LS-Dyna).

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Project Tree:
Frontal
Impactwith
Infinite
Rigidwall
• Plannar
Frontal
Impactwith
finitewall
• 40% offset
Frontal
Impactwith
Finite
rigidwall
• 25% offset
Improvement
1
• Seat belt
incorporated
for Dummy
Improvement2
• Use of
Composite
materilas

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Solution Procedure:
Step 1: Incorporating Steering
Steering with airbag
 Use rods to 1-d beams with Secbeam property and Matl1 Material. Give density and
elasticity values according to the units of Steering
Connect the beams as shown in
figure. In car we have a steering
part. Create a Spider to the
steering hole and attach the
spider to the steering node by a
beam resembling a steering shaft.
Use the same material and
Property.
Steering with beam elements connected to a node.

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Steering Set-up
Step 2: Seat Set-up
 Create to surfaces according to the dimensionsof the dummyin hypermesh
and import in to the car.
 Use Matl34 fabric material for the seat.
 Attach the seat to the floor of the car using the beams.
 Make sure that the units of car, seat and steering are same. Units of car
steering and seat are tons, mm and sec.

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Step 3: Converting car, steering and Seat into DummyUnits.
Conversion file
Step 4: Importing Dummy
 Never offset Dummyparts, it may give rise to Part out of Rangeerror.
 Open Dummyfile into ls prepost and Import car setup.
 Use limb-operations and h-pointoperations to adjustthe dummyin the car.
 Give Contacts between Dummyand Carfloor, Dummyand Airbag,
Dummyand Seat, also between airbag andCarwindshield.

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Step 5: Assign velocity for the complete car setup.
Velocity is 15.65 mm/ms
 Create a Node-set id for the complete car set-up and assign it in the *Initial Keyword.
 Velocity = 15.65 in X-direction

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Step 6: Creating a Rigid wall
Case 1: Infinite Rigid wall
 Create a Planar rigid wall (Infinite) normal to Z-direction. Important note make sure the
Z-axis of the rigid wall face the car.
 Create a base node for the rigid wall and adjust the rigid wall distance arbitrarily.
 Select all the nodes of car as a slave nodes because Ls-Dyna takes rigid wall as master
by default. Without this contact car passes through the rigid wall without any impact.
Case 2: 40% offset Rigid Wall
 Create a finite rigid wall similar to infinite case but in this case we give the rigid wall
some dimensions as shown in figure.
 Similarly assign the Slave nodes as in the previous case.

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Length in X= 1500 and Length in Y= 1500
40% off set rigid wall
Case 3: 25% offset Rigid Wall
 Construct similar wall as above but at 25% off set of car.
 Give the slave node set for the car similarly.
Length X = 1500 and Length Y= 1500

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25% Offset rigid wall
Step 7: Control cards, Binary plots, Hourglass
 Control Cards
Control termination for this model is127 ms.
We use defaulthourglassviscosity type 5
Control timestep is 0.001112

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Control cards
 BinaryPlots
 Select GLSTAT, RWFORC, RCFORC, SWFORCetc., in ASCII_Option
which are used for plotting all the results.

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Step 8: Run each case separatly with 256000000 memoryand 8 cpu as inputusing
Ls-Manager.
 Use D3Plotto view the results.

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Results:
Case 1: Infinite Rigid Wall
@ 0 ms
Infinite Rigid Wall
At 0ms

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@ 40ms
Frontal impact @40ms
@ 90ms
 If we observe clearly as the materialof the seat is fabric whichhas very
less stiffness it folds off after the impactand the dummyfall on to the
airbag.
 The contacts between airbagand dummypreventsdummyto penetrate into
airbag.

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@ 127ms
 At this timestep the dummycompletelyfallsonto the front dash board due
to strong impact.
 The frontal part of the car the bumpercrushes completelyand suddenly
comes to retardation whichgivesreaction to dummyand fallson to the
dash board.
 The airbag preventsdummycomingoutthrough windshield.
VonmissesStresses
 Maximum Vonmissesstress is 7.626 GPa
Von-Misses Stress

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Pressure
 Maximum pressure is 0.806061 units
Pressure
Total energy plot
 The total energy increases from 0.175e6 to 0.21e6 withtimeincrement
Total Energy

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Normal Force Plot
 The normal force acting on the rigid wallisthe maximum among allthe
cases as the contact area of the car increases completely.
 The maximum normalforce is 800 unitsat 45ms.
Normal Force
Head Injury Criteria
 In this case the Head Injury Criteria crosses the prescribed value10 so the
dummyisout of control and is considered dead in this case.

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Case 2: Finite Rigid Wall with 40% offset
@ 0 ms
Finite Rigid Wall with 40% Offset
At 0ms

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@ 40ms
At 40ms
 Only40% of the front part of car impactswiththe rigidwall.
@ 90ms
 The driverside of the car crushes completelyon to the rigid walland on
the other side, impactis less but in this phenomenon the dummyinjuryis
very high because the completeforces dueto impactare transferred only
on one side that is driverside (dummy).
 Also in this case the right roof rail and A-Pillaron right side deforms.

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@ 127ms
 The right side completelycrushes on to the rigid wall. Thisis one of the
dangerouscases because of the impactand stress transfer are all taking
placeon the side of the dummy.
 The airbag preventsdummycomingoutthrough windshield.
VonmissesStresses
 Maximum Vonmissesstress is 1.5289asthe impactison only one half.
Von-Misses Stress

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Pressure
Pressure
Total energy plot
Total Energy

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Normal Force Plot
 The normal force acting on the rigid wallisthe maximum on only right
half rather than on the completebody. So the normal force increases to
1000 unitswhichis more than the force acting on the infiniterigid wall.
 The maximum normalforce is 1000 unitsat48ms.
Normal Force
dummyisout of control and is considered dead in this case. The impactis
very high in this case.

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Case 3: Finite Rigid Wall with 25% offset
@ 0 ms
Finite Rigid Wall with 25% off set
At 0ms

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@ 40ms
@ 90ms
 The driverside of the car crushes completely dueto the impactof rigid
walland on the other side, impactis less but in this phenomenon the
dummyinjuryisvery high because the complete forces due to impactare
transferred only on one sidethat is driver side(dummy).
 Also in this case the right roof rail and A-Pillaron right side deforms
completelyon the dummy.

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@ 127ms
 The most dangeroussituation, the dummycompletelypacksin between the
crush. This is the most critical impact. Useof more composite materialson
the sideof dummyand alsoseatbelt maypreventdummydying.
VonmissesStresses
Von-Misses Stress

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Pressure
Pressure
Total energy plot
 The total energy increases from 0.175E+6to 0.181E+6withtime
increment
Total Energy

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Normal Force Plot
 The Normal force is 400 unitsat 45ms. Theforce is less as the impactarea
is less compared to the previouscases.
Normal Force
dummyisout of control and is considered dead in this case.

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Improvement 1: Incorporating Seat Belt for the Dummy in the
Infinite rigid wall case
 In this case the termination timeis75msonly. Velocity is 8.99ms
@ 0 ms
At 0ms
 The Dummyisincorporated withseat beltto preventit fallingforward due
to the impact.

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@ 40ms
@ 75ms
 In this case the seat belt holds the dummy. The Retractor and Sensor act
alternativelyin this case to hold the dummy.
 As the holds to its seat the impactof frontal crash is less on it.

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VonmissesStresses
Von-Misses Stress
Pressure
Pressure

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Total energy plot
 The total energy increases from 58.5e3 to 66e3 withtimeincrement. The
energy is less because velocity is reduced to 8.99.
Total Energy
Normal Force Plot
 The maximum normalforce is 200units.
 As velocity reduces the normal force impactingon the wallreduces
Normal Force

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 In this case the Head Injury Criteria is less than the prescribed value10 so
the dummyisout of danger.
 The mainreason for the dummyto resist the impactis dueto
incorporating the seat beltand also reducing the velocityto 8.99. With
15.656the program isending up without of range velocities.

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Improvement 2: Using Composite materials for front Bumper
and Left and right Fender
Front Bumper with left and right Fender
 Matl58 is used for composite materialand also each composite part have 5
composite layers.
 Thethickness of left and right fender composite layers is 2mm. Also the
thickness of bumpercomposite layers is 4mm.
Matl58 Composite Laminate Material
Left and Right Fender Part. B is layer angle Front Bumper Part

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@ 0 ms
At 0ms
@ 60ms
 The compositematerial takesmaximum impactand does not transfer it to
the internal parts. So that is an advantageof using compositematerial.

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@ 65 ms
 In this phenomenon the stresses are not transferred to the internal parts.
VonmissesStresses
 Maximum Vonmissesstress is 4.08405GPa
Von-Misses Stress

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Pressure
 Maximum pressure is 2.04913units
Pressure
 The pressure in this case is remarkable. Compositematerialshavethe
maximum stresses compared to all other materials. These restrain the
energy and breaksinto pieces withouttransferring the energy to the
internal parts.
Total energy plot
Total Energy
 The Compositematerialshavethe maximum energyamong allthe above
iterations. They absorb more energy and breakswithouttransferring the
energy whichin turn reduces the injury on dummy.

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Normal Force Plot
 Similarlythe Normal force is also high for compositematerials. These
have 2000 unitsof normal force at the impactpointwhichis maximum
among allthe abovecases.
Normal Force
 In this case the Head Injury Criteria is below the prescribed value10 so
the dummyisout of danger. Compositematerialssafe dummyfrom
injuries.

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Summary and Conclusion:
 During the analysis I faced few errors regarding the seat belt
element not found. We get this error if the seat belt retractor
and sensor are disconnected from the floor. So we need to
connect the seatbelt elements to floor with beams. Also check
the velocity node set id.
 25% off set causes more damage to the dummy and 40%
follows it. Using seat belt and composite materials at the area
of impact may reduce the damage.
 Composite materials are best preferred in the concentrated
impact area. The main advantage of composite materials is
they absorb the energy rather than transferring it to the other
components. By this they gain maximum energy and also have
maximum normal force which breaks them into pieces rather
than impacting the internal parts and damaging the dummy.
 Among all the iterations assigning Composite materials for
Bumper and fender has best results in saving the dummy from
impact followed by the seatbelt. So composites with seat belt
might be the best suggested product obtained by observing the
above results.
Note: Car, Airbag, Dummy models are separately taken from Class 8020
(Crashworthiness). Also Crashworthiness Project is also attached along with this
project. Each and every model is self-iterated and videos will be emailed. Can also
provide files of all the above iterations if necessary.

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