Assignment 6-Frontal Crash Simulation Challenge

AIM: To perform the crash analysis on the Frontal section of the car and to check whether the stress are acting on it.

Objective:The main objective is to do as the instructions

• 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 penetrations and intersection.
• Correct rigid bodies if any issues.
• Create rigid wall with friction 0.1.
• Compare the model weight with the full scale 300k nodes model and use added masses to reach target weight 700kg while getting CG about the required range.
• Initial velocity 35 mph.
• Use model checker to ensure good quality.
• Time-step :0.5 to 0.1 microseconds.
• Run 80 ms.

Task to Complete:

• Sectional force in the rails at location of indicated node 174247.
• Axial force received on the rails from bumper.
• Shotgun cross sectional forces.
• A pillar cross section.
• Acceleration curve received on the accelerometer at base of B pillar (on B pillar rocker).
• Intrusions on the dash wall 66695,66244.

Methodology:

The Methodology of the given Frontal section will be as the follows.

• Opening the the File.
• Checking the dimensions.
• Creating the interferances.
• Creating the Rigid Wall.
• Creating the COG points.
• Creating the Intial velocity.
• Performing the checks for the errors.
• Giving the Time-step and run the time values.

Theory:

Frontal area:

The frontal area of the car is called the crumble zome. It is so called as it the only part which gets collided(Most cases)with te others vechicles in the case of crash.The frontal area should be created based on the aerodynamics drag since it faces the air head-on.The total restiance of the car depends on the frontal area and the drag coefficent.The force exterted by the air moving through is aerodynamics drag.A good areadynamic shape is known to be a narrow edges to gradually increases the edges but that's afallacious fact.The good aerodynamic shape is a curved part but with a blunt on the windward side and gets slender on the Leewars side.

Procedure:

Opening the File:

• For Importing the given Model we should go to File>Import>Solver>select the starter file(_0000.rad)>select on the import.
• The model is imported in the geomentry by wire frame .
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• We should have to change the model from the wire frame to the shaded model.
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Checking the Units:

• For Checking the units of the given model in Radioos.
• We should go to the Model Browser>Cards>Being cards>Check the units like Input mass,length,time.
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• The units of the project are Mass(Kg), Length(mm),Time(ms).

Creating the Interface

• For creating the Interfaces goto Model Browser>Groups>Create>Type 11>Cilck on the componenets to be selected>Selecet the 74 components in the model.
• Give the values of Istf(stiffness definition) as 4, Igap (gap/element option) as 2, Idel (Nodes and segment deletion) as 2, Irem_gap (Deactivating slave nodes if element size is lesser than gap value, in case of self-impact contact) as 2, Irem_i2 (deactivating the Slave node, if the same contact pair/nodes have been defined in interface type 2) as 0, stfac (Stiffness or scale factor) as 2, Fric (Coulomb Friction) as 0.2, Gapmin (Gap for impact activation) as 0.5, Inacti (Deactivation of stiffness) as 6, Iform (Stiffness or viscous formulation) as 2.

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Creating of the Rigid Wall

• To create the Rigid Wall, the Solver browser needs to be opened.
• In the Solver Browser, Right-click on the tab area >> click on the RWALL >> select PLANE >> A new rigid wall card is created. Give a name to it >> Select the Geometry Type as “Infinite Plane” >> Click on the “XM, YM, ZM” (X, Y, and, Z Coordinates of Base node M) >> Select the node at the plane the rigid wall needs to be created >> Select the Normal around the axis and based on the direction of the normal give a ‘-’ sign based on it. >> Give the Slide value as 2, Dsearch value as 1000, Fric Value as 0.1.
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• The Rigid wall is Created.

Creating the Mass

• For creating the mass we should go to the Solver >Create a Mass>create a name>Give the Mass type as 0>Gmd ID:right click on tht and slecet on the Id>and see the mass of the Model >and we should have to bring to 700kg.
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• So gmid ID >click on the Enitity card>selecet the nodes in the required amount and click on the Create.
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Creating the COG point:

• After that we should have to check the COG of the point mass we should go the Tools >masses >see the COG value.
• We should have to create a COG point by go to >Geomentry>nodes>give X,Y,Z values and create a point.
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• This point is called COG point.
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Adding the Intial Velocity:

• We should have to create the intial velocity of the model
• we should create the Initial Velocity, In the Solver Browser, Right-click on the Tab area >> Click on Boundary Conditions >> Select INIVEL option >> Give a name to the card >> right click on the gmd_ID option >> click create >> Select the nodes as displayed and click proceed >> Give the Velocity value as 15.64 >> Select the coordinate at which direction the velocity needs to be added.
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• We can see the INIVEL is added to the model.
• Given Intial velocity is 35mph(miles per hour) we should have to do in the units system.
• we know that 1 mile =1.609mm and 1 hour=3.6ms
• V=35*1.609*10^6/3.6*10^6=16.54mm/ms
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Performing the Checks of error

• we should have to check the error in the model
• We should go to the Tools>Model checker>Radioos Block>Eroors>Run.
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• The Model is Run.

Check for the Pentrations:

• To check for penetrations, go to the Tools menu >> Click on the Penetration check >> In the Entity Editor, click on Selection and click on group >> give the group. In the Tab area, the penetrations are checked.
  There are no penetrations in the model.
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For Giving the Time step and the Run time Value:

• To go to the time step go to Model>Cards>clcik on ENG_ANIM_DT>in the Entity ediotr give the T frequency value.
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• For the ENG_RUN>Entity panel give the Tstop 80.
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Checking gor the Section and Frames:

For a pillar cross section.

• We should go to the solver>create a new Frame >Selecet the nodes> we should give the nodes>proceed.
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• After the frame is created we should have to create the section for that solver>sect>move>create.
• In the editing tab we shoud have to select the nodes >proceed>select the Frame id and select the Frame >Create the Ishell and select the elements of two rows>click on enter.
• Go the model browser >create a new output block> and entity ID>Right click on it>selecet the crossection>select the type and click on ok.
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For the Shotgun cross sectional forces.

• After the frame is created we should have to create the section for that solver>sect>move>create.
• In the editing tab we shoud have to select the nodes >proceed>select the Frame id and select the Frame >Create the Ishell and select the elements of two rows>click on enter.
• Go the model browser >create a new output block> and entity ID>Right click on it>selecet the crossection>select the type and click on ok.
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Axial force received on the rails from bumper.

• After the frame is created we should have to create the section for that solver>sect>move>create.
• In the editing tab we shoud have to select the nodes >proceed>select the Frame id and select the Frame >Create the Ishell and select the elements of two rows>click on enter.
• Go the model browser >create a new output block> and entity ID>Right click on it>selecet the crossection>select the type and click on ok.
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Acceleration curve received on the accelerometer at base of B pillar (on B pillar rocker).

• To create the Accelerometers, open Solver Browser >> Right click on the Tab area >> Click create >> Click ACCEL >> select the node as specified location above >> give the Fcut value as 1.65.
  The accelerometers are created and to call the accelerometers the following steps are created.
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  The card which is created needs to be called and therefore, to call the accelerometers, Go to the Model browser >> Right-Click on the Output Blocks >> click create >> give a name to the card as accelerometers >> Select the Entity IDs with the accelerometer and selection of the accelerometers is done.
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Intrusions on the dash wall 66695,66244.

• Creating of the intrusion, select the node at which the intrusion can be checked.
• Go to the Tools panel >> Click on numbers >> Select the nodes >> click on ID >> give the node id as specified (given 66695, 66244) >> Click on display.
• The node number is displayed.
• Now go to the Solver Browser >> right click on the tab area >> click create >> click SKEW option >> select MOV option >> give a name to it >> select the nodes ( origin, axis, Plane nodes)
  The coordinates are created.
• The card which is created needs to be called and therefore, to call the Intrusion, Go to the Model browser >> Right-Click on the Output Blocks >> click create >> give a name to the card as Intrusions >> Select the node (The number to which the number is displayed) >> Select the System (the Skew coordinates created).
• The instruction are created and called in the Model Browser.
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For the Analysis of the Given Model through Radioos:

• For the analysis we should go to the Analysis>Radioos>save it as the 0000.rad file >check the include connections and give -nt 4 >clcik on Radioos.
• We can see the file running in the Radioos we can get the elapased time and kinetic energy error and no of cycles.
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Hyper view :

• Go to the Hyper view tab and clcik on the file>on the .h3d file and run the simulation.
• And chsnge it to simulate>run the simulation of the model.
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Plot the Graphs:

• To plot the graph, go to the Client Selector option in the Tool Bar >> Change it to HyperGraph 2D >> The HyperGraph is opened >> Select the Data File from the respective folder >> Select Cross-sections, Parts > Internal Energy, Kinetic Energy, Total Energy, Hourglass Energy, Contact Energy > MAG >> Click Apply.
• The method is the same for the other cases.
• The Plots are created.

Internal Energy:

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• As the plot of the internal energy is increasing as the time step is increasing in the Graph.

Instructions -Disp Resultant Displacement

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• For the intrusions, the displacement curve is linearly increasing as the initial distance is noted as around 800mm but after the crash analysis, it is noted that the distance from the initial skew and final skew distance is around 900mm at the time 80ms.

Section crossection of pillor,Bumper,short gun

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• Observations:

  It is observed that during the animation the deformation majorly takes place in the frontal area and the stress is passed to all the other components evenly by disrupting the shape of the frontal section but we can observe that the impact of the crash is taking only at the frontal region trying to save the driver seat area and the passenger seat but the impact is more and therefore it can injure the driver and passenger.

  For the cross-sections of the parts, the Curve hits a peak value and the forces decrease after attaining the peak Force. The Cross-section creates a Force- time Graph and shows how the force is acting on the section at the particular time is known.

  The Energy graph shows that the Hourglass and the Contact energy have a value near to zero. Total energy shows the summation of Internal energy and Kinetic energy. The decrease in the internal energy and the increase in kinetic energy leads to an almost straight line of the total energy.

  For the Accelerations graph, the acceleration fluctuates drastically during the crash. Before the Crash, the acceleration will be maintained constant.

Acceleromter graph

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Terms used:

Centre of Gravity:

The center of gravity (COG) of an object is the point at which weight is evenly dispersed and all the sides are in balance. A center of gravity can change as the mass changes but in many other cases, it's a fixed location.

Accelerometer:

An accelerometer is a device used to measure the acceleration (It is the rate of change of velocity) of a body. The accelerometer is typically used for linear type of acceleration based on vibration.

Type 7:

The general purpose of the TYPE 7 interface is that it can simulate all types of impact between a set of nodes and a master surface. Automatic node to surface contact gap can be constant or variable. The main advantage of this type of interface is that the stiffness is not constant and increases with the penetration preventing the node from going through the shell mid surface.

Rigid Wall:

The Rigid wall is a virtual wall created to perform the crash analysis on the body. The Rigid wall has no certain shapes or dimensions. It can be made as flexible as possible and It can sustain the load and thus, helping out to get a crashworthiness analysis.

Penetrations:

Penetration as the name suggests, a node gets penetrates the element and causes it to fail during the simulation. The penetrations are to be removed to get a better result.

Intrusions:

An intrusion generally means to get into one’s own property or territory. In HyperMesh Intrusions are checked to see if the component is withstanding crash making sure that the component doesn’t fail miserably.

Initial Velocity:

Initial velocity is the velocity of the object before the change in acceleration.

Learning Outcomes:

• In this project we have covered the topics how to create Rigid wall,intial velocity,Checks the masses and centre of gravity(COG)point in the model.
• we have learn about the Intrsuions, acclemeter and creating in the model output block.
• Learn to create the cross sections and creating the model ouput blocks.