Assignment 6-Frontal Crash Simulation Challenge

AIM:-To simulate the model to perform frontal crash and observing the deformations and plot the graphs for all the mentioned requests and energies.

OBJECTIVE:-

• To Check the unit system and either follow[Mg mm s] or [Kg mm ms].
• To Compare the model weight with the full-scale 300k nodes model and use added masses to reach the target weight of 700kg while getting CG about the required range.
• To Create an appropriate interface, friction 0.2, and recommended parameters.
• Make sure of no penetrations and intersections.
• To Correct rigid bodies if any issues.
• To Create a rigid wall with friction 0.1.
• To Create an inivel solver card Initial velocity 35 mph (15.6464mps).
• To Check Time-step to be 0.5 to 0.1 microseconds and Run 80 ms.
• To Output requests for Sectional force in the rails at the location of indicated node 174247.
• To Output requests for Axial force received on the rails from the bumper, Shotgun cross-sectional forces, A-pillar cross-section.
• To Output requests for Acceleration curve received on the accelerometer at base of B pillar rocker parallel to each other.
• To Output requests for Intrusions on the dash wall for nodes 66695 and 66244.
• To use model checker to ensure good quality.
• The simulations are run on hyper view for displacement and Von Mises.
• To plot the graphs by using hypergraph 2D for rigid wall forces, internal energy, hourglass energy, contact energy, and total energy.
• To plot the graphs by using hypergraph 2D for all the output requests.
• To plot the graphs by using hypergraph 2D for rigid wall forces, internal energy, hourglass energy, contact energy, and total energy individually for better understanding.
• To check the energy error and mass error for the base simulation.

THEORETICAL EXPLANATION:-

The ideal frontal crash test procedure will evaluate the potential for occupant injury from both deceleration severity and intrusion. Furthermore, in addition to occupant protection, the ideal test procedure will not lead to designs that jeopardize the vehicles’ crash compatibility with its collision partners. Finally, the test conditions (i.e., impact speed, impact angle, and impact partner) must encompass and be representative of the frontal crash environment to which passenger vehicles are exposed on the highway as shown in fig 1.1.


fig 1.1

The objective of a crash test for Federal Motor Vehicle Safety Standard (FMVSS) No. 208 is to measure the crashworthiness of a passenger vehicle. The standard specifies performance requirements for the protection of vehicle occupants in crashes. Historically, this has encouraged improvements to the vehicle structure and restraint systems to enhance occupant crash protection. Structural design for crashworthiness seeks to mitigate two adverse effects of a crash.

• Degradation of the occupant compartment survival space
• The occupant compartment deceleration severity.

Both effects have the potential to cause injuries – first, because of the increase in the probability of occupant contact with intruding vehicle components, and, second, because of the potential for internal injuries to occupants. The degradation of the occupant compartment survival space is measured by the intrusion, while occupant compartment deceleration severity is measured by the amplitude and time duration of the crash pulse as shown in fig 1.2.

fig 1.2

PROCEDURE:-

*The unit system is been checked to start the simulation in hypercrash as shown in fig 1.3

fig1.3

*The model has been imported by drag and drop method as shown in fig 1.4

fig1.4

*The mass balancing is been checked and the COG is also in the initial as shown in fig1.5 and can add the mass of 700 kg as mentioned in the task.

fig1.5

*The model has been imported from hypercrash to hpypermesh so all solver cards are been updated as shown in fig 1.6.

fig1.6

*The contact group is created with a TYPE 7 and all required parameters have been updated as shown in fig 1.7.

fig1.8

*From the Eng_Run time is been updated as the mentioned 80 ms as shown in fig 1.9.

fig 1.9

*From the ENG_DT BRICK, ENG_DT INTER, ENG_DT NODA the time step is been updated as the mentioned 0.5 and 0.1 microseconds as shown in fig 1.10.

fig1.10

*The rigid wall is been created with all parameters mentioned by selecting the node for wall location and normal as shown in fig 1.11.

fig1.11

*The Initial velocity value is been added by selecting the create, boundary conditions,inivel, and adding initial velocity of 15.6464 in X-axis coordinates as shown in fig 1.12.

fig1.12

*The Accelerometers are been added by selecting the create <ACCEL, the accelerometer are added on B-Pillar Rockers by selecting the opposite node in both the rockers that can be used for output request for acceleration attained by the rocker after impact as shown in fig1.13a,1.13b & 1.13c.

fig1.13a

fig1.13b

fig1.13c

*The mass is added strategically to make sure the overall weight of the car is not exceeding 700kg and distribution of weight concentrating on the driver and passenger compartment as shown in fig 1.14.

fig 1.14

*The mass balancing panel shows the final mass to the system and the location of the COG, the COG is bove the center cross member for better simulation as shown in fig 1.15.

fig1.15

*The section is created in the mentioned region to provide a time history so the force acting in the regions can be recorded as shown in fig 1.16.

fig1.16

*The rigid body is created in the suspension towers to provide a time history so the force acting in the regions can be recorded as shown in fig 1.17.

fig1.17

*The Spring elements are created in the driver floor panel to provide a time history so the Intrusions in the regions can be recorded as shown in fig 1.18.

fig1.18

*The Model checker is run to check for any error, there were no errors so the model can be proceeded to run the simulations as shown in fig 1.19.

fig 1.19

*The simulations are run on hyper view for displacement and Von Mises and have been animated as shown in fig 1.20.

fig1.20

*Hypergraph 2D mode is turned on and graphs have been plotted for Internal energy, Kinetic energy, Hourglass energy, Contact energy, and total energy graphs concerning global variables for Frontal Crash as shown in fig 1.21.

fig 1.22

*The graph is been plotted using the spring elements 110002,110013,110018 and110019 with respect to time for total elongation in the spring elements in mm as shown in fig 1.23.

fig1.23

*The graph is been plotted using the spring elements 110020 and110021 with respect to time for total elongation in the spring elements in mm for the driver side door panels. The intrusion of these springs' values must not exceed 150mm(15cm), the intrusion recorded in the springs are 83.62mm(8.362cm) and 73.279mm(7.3279cm) which is safe as shown in fig 1.24.

fig1.24

*The graph is been plotted for the components with self contact with neighboring components for TYPE 7 contact the max value of force among them is 155.233 `(Kg*mm)/(ms)^2` as shown in fig 1.25.

fig1.25

*The graph is been plotted for the Sections created for the right side or passenger side the max value of force among them is shown in fig 1.26.

• For Right Rail section 42.1017 `(Kg*mm)/(ms)^2`.
• For Right Shotgun section 9.79817 `(Kg*mm)/(ms)^2`.
• For Right Bumper section 26.7138 `(Kg*mm)/(ms)^2`.
• For Right B-Pillar section 5.95448 `(Kg*mm)/(ms)^2`.

fig1.26

*The graph is been plotted for the Sections created for the Left side or Driver side the max value of force among them is shown in fig 1.27.

• For Left Rail section 19.5407 `(Kg*mm)/(ms)^2`.
• For Left Shotgun section 8.2047 `(Kg*mm)/(ms)^2`.
• For Left Bumper section 28.6937 `(Kg*mm)/(ms)^2`.
• For Left B-Pillar section 7.70813 `(Kg*mm)/(ms)^2`.

fig1.27

*The graph is been plotted for the Accelerometer which was placed on B-Pillar Rockers parallel to each other the values recorded are shown in fig 1.28.

• For Left B-Pillar section 8.29529 `(mm)/(ms)^2`.
• For Right B-Pillar section 6.35491 `(mm)/(ms)^2`.

fig 1.28

*The internal energy starts from origin due to there being no contact between the Rigid wall and Car BIW. So the internal energy goes on increasing, proportionally the deformation or displacement is happening, when the displacement increases the internal energy increases as shown in fig1.29.

fig1.29

* Kinetic energy is high and then decreases, due to there being velocity applied to the Car BIW, so it's getting deformed and the kinetic energy decreases the graph has been plotted for Kinetic energy and time as parameters as shown in fig 1.30.

The formula for Kinetic Energy=`(1/2)*(m*v^2)`

Given Data

Mass=700 kg

Velocity=15.6 mmms">`(mm)/(ms)`

K.E=`(1/2)*(700*(15.6464)^2)`

K.E=85324.2 `(Kg*mm^2)/(ms)^2`

fig1.30

*At initial the there will be no impact so the Contact energy will be at zero and then as the deformation starts Contact energy increases gradually with respect to time. The graph has been plotted for Contact energy and time as parameters as shown in fig 1.31.

fig1.31

*The Hourglass energy is been occurred in the simulation the max value attained is 252.463`(Kg*mm^2)/(ms)^2`. Which is below the permissible range that is less than 10% of the internal energy as shown in fig 1.32.

% of Error = `((252.463)/(42974))*100=0.587%`

fig1.32

*Since Total energy is the summation of all the energies so at the start there will only be Kinetic energy so the total energy will be equal until the deformation starts Total energy averages all energies with respect to time. The graph has been plotted for Total energy and time as parameters as shown in fig 1.33.

fig1.33

*Engine Output File [0001. out] has been generated after analysis. The Engine Output File [0001. out] contains the data of the analyzed errors are in the permissible range values as shown in fig 1.34.

fig1.34

*The graphs have been plotted by using hypergraph 2D for rigid wall forces, total resultant elongation for springs, Sectional resultant forces, Acceleration, internal energy, hourglass energy, contact energy, and total energy and are verified siminatusly as shown in fig 1.35.

fig1.35

RESULT:-The model was simulated to perform the frontal crash test and observed the deformations and plotting of the graphs for all the mentioned requests and energies.