FRONTAL CRASH ANALYSIS OF A CAR IN HYPERMESH RADIOSS

FRONTAL CRASH ANALYSIS OF A CAR IN HYPERMESH RADIOSS

Objectives: To study force and energy received at different component of neon BIW and other objective is to create a global contact interface, rigid wall, add the masses to reach a target weight of 700 kg while getting COG about required range on neon BIW

Setup and Executions

• Open hyper mesh and choose RADIOSS interface
• Then import the 0000.rad file
• Check for correct unite system-> kg mm ms
• Open model in browser tab and select cards-> Begin card
• Check for the unite of mass ,length, time

Pre-processing:

• The front BIW portions of a car are considered for frontal crash analysis. Initially it consists of 74 parts in three assemblies. With total number of nodes 9904892. The initial mass of the structure is 188 kg

Checking initial connectivity:

• After checking connectivity there was 2 free spherical joints of Id 110013 and 110002 as shown below. Which are deleted since it was not connected to other part

Interface:

• Create an appropriate interface with friction 0.2 and recommended parameters, Already a contract is defined in the model we have to delete that interface and to create a new interface type7 with recommended parameters.

Penetrations & intersections

• Now run the model analysis to check for errors and warnings.
• Make sure of no penetrations and intersections. If there is any penetrations correct it or simply use the gamin value to reduce the penetrations.

Rigid wall creation:

• An obstacle like infinite rigid wall is created before bumper with some parameters like frictions =0.1 and Dsearch as 1000
• Rigid wall is created by clicking on solver –right click- create-rigid wall –plane then dialogue box will open and assign the required Values.

Initial velocity:

• We have to create a initial velocity in order to perform the crash.
• We have created an initial velocity with 15.6464 mm/ms in VX-direction which is perpendicular to rigid wall

Creating Accelerometers:

• To get accelerations curve received on the accelerometer at base of A & B pillar
• Click on solver – right click – create –accelerometers
• We have to create the accelerometers on both side just simply click on the node and select the node at respected place

Creating Intrusions:

• We have to create an intrusions on the dash wall at a locations of 66695 , 66244, to know the displacement of the particular wall into the occupant area. For this we have to create a fixed skew and make the respected node number in one position the below figure shows

Cross sections creation:

• We have to create the cross sections to know the force acting on those particular sections. we have to create sections on the following component , with both right hand side as well as left hand side
• Go to solver –right click- create- sec-ok then a dialogue box will be open
• Before creating the cross sections we have to create a movable skew at the respected locations and add that skew in this dialogue box .then select the elements around that skew in at least two columns of the element thought out all sides as shown below.
• Select the grshel_id if we got the quard element at respected skew and select the grtria_id if we got the element at respected skew. Assign some value to that card such as Isave as 0,delta T as 0.1 alpha as 0.65 and iframe as 12.perform the same method for other components and create the required cross sections

Mass addition & C.G:

• Initially the model has a weight of 188.42 kg we have to add the mass to reach a target weight of 700 kg to get the COG about the required range we have to add the Mass at the floor of the BIW in order to get the COG at required range
• once Mass is added check the COG of model

Creating output Blocks:

• Creating output block for accelerometers, intrusions and cross sections

Runtime and time step:

• The run time is set to 80 ms and ANIM/DT is 0.5 ms and also check for time step shown below.

Model checker:

• Right click on error and select Run to Determine the error and the Error tab opened to view errors
• After completing pre-processing the model is checked through model checker. Initially there was 2 error first was error Id 59 regarding property of the spring element.
• If no errors, proceed for the simulations run else solve the error and then run simulation

Run the Simulations :(by using Radios as solver )

• After creating all required out puts in hyper mesh, we have to run the simulations By using Radioss (solver) keep the export options as all run options as analysis , run number as 1 , options as –nt 4

Processor (solver):

• From Front_crash_0001.out file, the Total number of cycle was 79900. The energy error is -1.6% which is acceptable limit. The mass error is which also less than 5% it is acceptable. The run was “normal terminated’ which implies the processor successfully completed. There was no sudden changed in energy as well as in error. as shown below

Post-processing:

• Observe the animation run and analyse the change occurring in elements and their reactions for a period of 80ms
• Similarly analyse using contour ( select contour icon on toolbar)
• Select result type as displacement or Vonmises , averaging method as simple also use maximum and minimum measurement plotting using measures icon in the toolbar
• Displacement
• VonMesis

Plot:

• plot graph for Global variable which includes – hourglass energy, Total Translational energy, internal energy, Kinetic energy, contact energy
• then create graph for Accelerometer
• create graph for intrusions
• create graph for cross sections

Energy:

• the hourglass and the contact energy has low energy with respect to time
• Kinetic energy decrease with an increase in the internal energy. Kinetic energy is transformed into internal energy during the crash
• The total energy is nearly constant ,so there will be an energy balance on both sides of the equations
• The hourglass and the contact energy is not physical energy and it needs to be reduced.

Intrusions:

• The below figure shows the graph of maximum displacement with respect to time

• The purpose of intrusion to know the displacement of the node in the occupant area.
• we can observe there is maximum displacment change in nodes

Accelerations:

• The below figure show the graph of accelerations with respect to time

• The accelerometer are placed at the bottom of the A&B pillar on rocker component as show in below
• In left side accelerometer the maximum accelerations is 354m/s at t= 5ms and then falls suddenly and goes decreasing further. This jerk is caused due to the impact of the car
• In Right side accelerometer the maximum accelerations is 240m/s at t= 2ms and then falls suddenly and goes decreasing further.
• It observed that there are more jerk observed in left side then right side

Cross- sections

1. Shotgun (right and left)
2. The below graph shows total resultant force on left and right shotgun

• It is area where there is maximum impact due to collision. cross sections is introduced to observe the forces as shown below
• The below graph shows total resultant force on left and right shotgun
• There is different between right and left cross sections of shot gun due to uneven distribution of forces of force, pitching and yawing effect
• In left cross sections the maximum resultant force of 0.5 kN at t=48ms. and then there is decrease in force
• In Right cross sections the maximum resultant force of2.68 kN at t=45ms. and then there is decrease in force

2. Rail component
3. The below graph shows total result force on left and right rail component

• This is import since force get transfer through rail to the main structure
• In left side rail component at the time of impact there is maximum force is generated at t=68 ms of magnitude 3.4Kn then there is decrease in force
• In Right side rail component at the time of impact there is maximum force is generated at t=80ms of magnitude 0.3Kn then there is increase in force

3. Fender
4. The below graph shows total result force on left and right fender component

• Fender is part of the component supported with the rail component also we also need the force distributions result in that component
• in left side fender component at the time of impact there is maximum force is generated i.e. at t=60ms of magnitude 90 KN then there is decrease in force
• in right side fender component at the time of impact there is maximum force is generated i.e. at t=50ms of magnitude 19 KN then there is decrease in force
• There is more jerks are observed in left component compare to right one it is due to collision

4. Pillar
5. the below two graph shows total result force on left and right A pillar component

• In right component of the A pillar there is no hike in force at t = 20 ms the force of 0.2Kn is occurred. The right side component the forces increases gradually till t=80ms the force increase due to self collisions .
• In left side there is minimum force are transfer due to banding effect and some forces are observed by the component. the maximum forces develop in A pillar left side is 2.7 kn at t= 55ms after that it decreases
• At left side A Pillar maximum force is transfer compare to right side

5. Hinge Pillar
6. the below two graph shows total resultant forces on left and right hinge pillar component

• In hinge pillar very less forces are observed compare to other component. The Maximum force on left side hinge component is 0.08 KN at t= 38ms.
• very less force are observed

Conclusions:

1. The maximum force are development in the rail component and least in hinge pillar
2. The forces generated in component from Maximum to Minimum as rail component ,Fender, Shotgun, A pillar and hinge pillar
3. From accelerometer it is clear that there are more jerks on right side compare to the left side
4. Finally What We conclude in the energy is absorbed by components with a decreasing Manner
5. However some sort of energy will be impact by the passenger in a real life crash senario

link for file : https://1drv.ms/u/s!AlDYq9nTGAGCiHarbylIaZjxFhHP?e=fzV0RJ