Assignment 7-Side Pole Crash Simulation Challenge

OBJECTIVE :

1 . To run the Side crash Simulation for the given model with the following Case Set up:

•  Follow the  unit system  of  [Kg mm ms].
• Creating the  appropriate interface with friction value of  0.2 and recommended parameters.
• Making  sure of no existence of penetration and intersections.
• Creating rigid wall with friction 0.1 as per reference model.
• Comparing  the model weight with the reference model and using added masses to reach target weight  of 700kg while keeping the  CG in the required range.
• Initial velocity of 35mph.
• Using the  model checker to ensure good quality.
• Keeping the Timestep in the range of 0.5 to 0.1 microseconds.
• Running the Total simulation for a time of  80ms.

2. To Plot the Results for the following 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.

Fig 1 Given model for side crash simulation

CASE SET UP & EXECUTION :

1. Unit System :

        The Unit Sysytem in the begin card is kept at Kg, mm & ms for Mass, Length & Time respectively.

Fig 2 Unit system in the Begin Card

2. Creating Type-7 Interface 

                     The intreface card is created in the solver for the Interface type-7 . All the nodes are selected for the Master and slave groupings and the following values are given in the card :

     Istaf = 4 (for Stiffness scale factor determined based on main and secondary characteristics)
     Igap = 2 ( Variable gap + gap scale correction after being computed)
     Idel = 2 ( When an element is deleted the corresponding segment form the main segment gets deleted)
     Friction = 0.1 (Prescribed value)
     Stmin = 1
     Gapmin = 0.5
     Inacti = 6 ( gap is variable with time but intail penetration is computed)
     Iform= 2  (Stiffness incremental formulation)

Fig 3 Creating the Interface Type 7

3. Applying the Initial velocity

             The Initial velocity is applied by creating the INVEL card in the solver and the initial velocity value of 15.64 mm/ms i.e, 35 mph is applied in the Y- direction. The Grnod for which the Intial velocity is to be applied are selected in the card.

Fig 4 Applying the Initial velocity

4. Creating the Rigid Wall

        The Rigid wall is created by creating the /RWALL /CYL card in the solver. The Cylinderical wall is created adjacent to the car door at some distance from the door. The Diameter of the Pole created is 254 mm. The Dsearch value is kept at 1000. The value for the friction is given as 0.1 .

Fig 5 Creating the Side pole Rigid wall

5. Adding the mass to adjust the Cog ang the Total weight

        Masses are added to the selective nodes to shift the COG to the required range and increase the overall weight of the model to 700 kg by creating the Solver mass card in the model browser. The COG is checked in the mass Details of the tool.  

 Fig 6 Adding the mass in solver mass  

  Fig 7 Total mass and COG Coordinates   

6. Creating the Intrusions in the Output Blocks for B-Pillar, hinge Pillar, Fuel Tank & Inner Door.

    i) Creating the Moving Skews Opposite the Intrusion nodes

         The Moving Skew cards are created in the Solver and the new Moving skews are created in the opposite direction.

Fig 8 Creation of the Moving Skew 

       ii) Creation of the Intrusions in the output block

             The intrusions are created in the Output block and the respective Moving Skews are Selected for the Output blocks as well as the corresponding nodes.  

Fig 9 Intrusions created in the Output block

7. Creating the Sections at the Cross members

         The Cross Sections are created in the cross Memebers by Creating the respective Moving Frames and then Creating the Sections by Creating new Sectional cards in the Solver. The corresponding Moving frames are selected in the sectional cards along with the elements across which the sections are to be created.

Fig 10 Creating a moving Frame

Fig 11 Creating a new Section

           The Newly Created Sections are added in the Output block as shown in the following Image.

 Fig 12 Adding the new sections in the Output blocks

 8. Checking the model using the model checker

         The model is checked using the model checker in the tool and any error or warning is corrected before running the simulation.

RESULTS:

1.Sectional Force in the Cross member

Fig 13 Sectional Forces across the Cross members

Observation :

       The Total resultant Force across the cross section of the  maroon Cross Member is very High as compared to the Purple cross member. 

2. Energy Curves

Observation :

      There is slight decrease in the Overall energy where as there is an increase in the Internal energy with time. The kinetic Energy keeps decreasing with time.

3. Intrusion Plots

 Fig 15 Intrusion Plots

Observation :

    The Plots indicate the displacement and hence the in crease in the deformation of the body with time. One way of reducing the Fuel tank intusion is by placing the cross member across the fuel tank region.

3. Peak Velocity of the inner node of the door

Fig 16 Peak Velocity of the Inner node of the door   

Observation :

     The Peak Velocity of the Inner node of the door is 16 mm/ms i.e 36 mph.

CONCLUSION:

 The given crash model was succesfully run and all the results were tabulated succesfully.

Fig 17 Crashed Model