Frontal Crash Analysis of a car s BIW model using HYPERMESH

OBJECTIVE

The objective of the challenge is to perform the frontal crash for the given simplified car model and to analyze the changes and the errors in energies due to the impact of the car on the rigid wall.

PROCEDURE

• CREATE INTERFACE ----- As to create the interface of type7 which is most appropriate suitable interface used over for all crash analysis so that it is assigned with recommended parameters as followed
  • Two interfaces of type 7 are created as Self contact and the contact between the rail and the bumper of the car.
• CREATE RIGIDWALL ----- As the crash analysis requires the rigid wall that car is imposed with velocity as it moves with a certain velocity and the crashing the rigid wall so as due to the crash of the car and the deformation and the energies transformation through the structure of the car model can be analyzed. The rigid wall is created with the friction of 0.1.

• MASS BALANCING----- As for this frontal crash the mass of the simplified car model is preferred to be a range of 700kg. and after the mass addition, the Centre of gravity is also to be maintained as below to floor of the model. The mass is added to the model from 188 kg to 700 kg and the COG is maintained at the center.

• ASSIGNING THE INITIAL VELOCITY ----- As the car is about to crash at the speed of 35mph. so that by assigning the INIVEL boundary conditions to the car model as it inerts the model to move at speed of 35mph.

• OUTPUT REQUESTS
  • The output request is defined by creating the TH/SECT card for the particular cross-section.
  • As the sectional force is to be noted down at sectional area around the node ID-174247. And the sectional force for the shotgun cross-section for both sides. Also, the A-pillar cross-sectional force is to be analyzed.
  • By creating the accelerometer at the B-pillar base rocker to get the acceleration.
  • The intrusion of the given nodes is requested to find the displacement of those particular nodes with the frame of reference as MID-rail.
    • Node ID-66695,66244

OUTPUT

• The sectional force around the node ID-174247. As the reaction force acts according to the contact of the rigid wall and the car bumper. Thus the particular crosssection acquires a load of higher at first contact between the rigid wall as the deformation starts to happen the force through the cross-section decreases for a moment and thus increases as the next self contact happened in crash simulation. So that the again jerk happened in the graph.

• The axial force between the interface created for the rail and the bumper part is observed.

• The shotgun cross-sectional force- The shotgun resultant force difference is because the force reacted at cross-section located at the different places in the left and right shotgun as this makes the difference in the force at the crosssection. As the right side cross-section in the right shotgun is created less distance from the rigid wall so that when impact happens, the reaction at the cross-section differs from the left shotgun cross-section as it the left cross-section is created little more distance from the rigid wall than the right side cross-section. Here at the shotgun cross-section, the force differs due to the position of the crosssection created as that the impact reaches the cross-section.

• A-pillar cross-section- The total resultant force on the cross-section created on the A-pillar on the both sides of the car.

• The acceleration curve noticed by creating the accelerometer on both sides B-pillar rocker.

• The intrusion of the dash wall as the particular nodes were observed. NODE ID-66695,66244 . As the displacement of these nodes as because the velocity is given so that no reaction occurred in the crash for this node particularly. This intrusin obsrvation is to measure the area that is affected due to the crash in which these nodes are located.

• Energy error- As the energy observation of this crash simulation is done.
  • internal energy increases as the impact happen the energy stored in the form of stress is increased.
  • The Kinetic energy decreases because of the velocity decreases as the crash happens.
  • contact energy is less because of the interface is created between the rigid wall and the car model.
  • Hourglass energy is negligible because of the many parts in the model though these are created with QEPH element formulation.

RESULT

The frontal crash simulation of the given simplified car model was performed.