frontal crash

OBJECTIVE

To simulate the frontal crash analysis of neon biw is by creating a rigid wall infront of the bumper to impact .the distributed mass of 700kgs is created to move the COG of model at the middle and near to drivers area .finally the simulation is pre-processed using hypermesh ,then run using RADIOSS as solver.various output result like axill force received on bumper ,forces received on cross sectional areas are studied using HYPERVIEW and HYPERGRAPH.

WHY VEHICLE CRASH ?

The vehicle’s crash analysis was used to the body structural analysis and occupant passenger behavior analysis. Analysis of the body structure has the kinetic energy of the body resulting from the absence of skeletalBbody collision energy can be transformed through a body that has a lot to absorb crash energy is delivered to passengers is to reduce the crash energy. In contrast, the seat of the occupant behavior analysis, seat belts, such as airbag restraint systems through the passenger has a purpose, trying to reduce the injury value. In this paper, safety tools of passenger injury, but at less cost reduction has been much research. When the cause of vehicle crashes, the passengers inside the vehicle and the vehicle must be able to afford the same rate changes and can be free from injury. If the passengers inside the vehicle can move freely without restraint from the vehicle during a collision with the passenger\'s velocity relative to the speed of the car has a large value is formed inside the vehicle. However, in the passenger seat belt is to be bound by the movement that causes the deceleration of the body more time can be extended and passengers also can shrink thesize of the damage that will be less.

Crashworthiness model

Crashworthiness modelDuring an accident, the capability of vehicle structure to absorb the energy is defined as crashworthiness. The vehicle must be designed such that, at higher speeds its occupants do not experience a net deceleration.

The advantage of the explicit FE method is that due to the nature of the computational approach, extremely small time steps coupled with an iterative solving method. The The collision transformation begins in the early part of the
bumper by about 8 m/sec from the front side member and the sub-frame was the metamorphosis begins. Then about 10 m/sec from the front frame body consists of the crash about 14 m/sec in the sub-frame and main frame is the start of the collision. The front frame collapsed in the driver\'s seat the bottom of the sub-frame caused the transformation, but in the dashboard panel confirmed that the strain appeared too small. the deformation
behaviors of the front frame and the frame has been modified from conflict and at the same time. We conclude that the crash energy can be absorbed. A can be seen from front frame and the frame suspension mounts are
connected to the frame associated with the departure of the wheel during a crash because it can lead to inability to drive.

FRONTAL IMPACT ANALYSIS

Radioss non-linear finite element processor which can be used to solve any kind of explicit problems. Usually in frontal impacts the vehicle undergoes heavy deformations on the front end whereas the central and the rear portions hardly undergo and deformations. Since these models are developed for frontal impacts, the front frame of the vehicle is meshed finely and the middle and the rear frame of the vehicle are coarsely meshed in Fig. 2. The type of analysis used FMVSS 208 Occupant Crash Protection on the modified regulations for non-rigid wall 35mph.

MODEL SETUP

• the model is imported using hypermesh and hypercrash ,then run model analysis to check for errors and warnings.
• there are no penetrations and intersection in this model
• some contact interfaces are alredy defined for individual parts ,but i would like to make this model with proper self-contac ,so those defined contacts were also deleted.
• now the meshed model of neon Biw is redy for pre processing .the unit system followwed is KG KN MM MS.

CONTACT INTERFACE

THE TYPE 7 contact interface is used to define self contact for the whole mode.the nodes are assigned as slaves and the elements are assigned as master.

RIGID WALL

an infinite plane rigid wall is created infront bumper for crash scenerio.the parameters like friction 0.1 and dsearch :1000 mm is defined.

PROPERTY CARD

the shell property is edited according to the recommended parameters like ISHELL=24 (QEP SHELL FORMULATION) and ISOLID =24(HEPH with physical stabilisation ) are assigned to reduce the hourglass effectson shell and solids.

ADDED MASS

the distributed mass of 700kgs is added ti floors and B-pillar.these distributed mass are added using admas card 1d panel.the added mass are assigned to move COG of model to the middle and right next to the driver because the COG is a main thing to define rolling behaviour of model when the event of crash.

INITIAL VELOCITY

the initial velocity of the model is 35Mph which is 15. m65mm/ms. because the whole model is in KG KN mm ms.the initial velocity is given for entire model in positive X-axis direction.

• The cross sections are created on some parts of the car body to analyze the forces experienced in the particular part or area.parts where the section created are A-pillar left right ,shotgun left right,rail left right,Hinge pillar left right, bumper rail left right,all the cross sections created by using the frame ,local co-ordinates.

• the Accelerometer is created at the rocker and base of the B-pillar,to measure the velocity at the B-pillar at the time of crash and also a sensor for the same accelerometers.

• the output block or data history for all the cross sections ,contact interfaces accelerometer and also for the node 66695 and 66244.for creating output block for the node ,create a frame of referance

RESULT OBTAINED BY THE HYPERVIEW

DISPLACEMENT

VON MISES

OUTPUT REQUEST.

• sectional force in the rails at location of indicate node 174247.
• shotgun cross sectional forces.
• a pillar cross section.
• acceleration curve received on the accelerometr at base of B pillar.
• intrusions on dash wall 66695,66244.

ENERGY

• the hourglass and the contact energy is not phys above graph shows that the kinetic energy is high at the starting and goes on decreasing when the frontal body crashes onto the rigid wall.
• the kinetic energy decreases 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 equation.
• the hourglass and the contact energy is not physical energy and it needs to be reduced.

INTRUSIONS ON THE DASH WALL 66695,66244

dash wall intrusion describes a situation in which frontal components of BIW and an automobile engine penetrate the space normally allocated for the feet of the front seat occupants.it is used prevent injuries in the driver and passenger lower leg and feet.

Distance between te node 66695 to 121739 IS 150mm and 66244 to 122047 is 140mm

shotgun cross sectional forces.

the maximum force observed on shotgun LH and RH are 18KN and 14KN. during crash ,after impact on rail bumper next that gets impact or deformed is shotgun.shotgun helps to reduce impact on A pillar because of its shape and composition of materials.as compared to rail force absorbed by shot gun is less.uneven distribution of forces occurs in model due to uneven distribution of mass on left and right side.

Sectional force in the rails at location of indicate node 174247.

The maximum force observed on cross-sections of rail LH is 2.4 KN and Rail Rh is 6.2 KN.more force is observed on right cross section of rail is due to right side cross section being more stiffer as compared to left rail.also thre is one reason which is distribution of mass on left and right side of car. as we know force is directly proportional to mass ,more mass on one side more force observed on it.when rail on left and right side starts to get impacted against rigid wall maximum force is observed on them once it starts to get deformed force starts to decrease thus kinetic energy starts decreasing.96

A pillar cross section.

The maximum force observed on A pillar LH and RH is 5.5 KN and 5.2KN.since the majority of force or load is absorbed by rail,bumper,shotgun,load absorbed on A pillarleft and right is comparatively less.uneven distribution of forces is observed due to uneven distribustion of mass on left and right side.

Acceleration curve received on the accelerometr at base of B pillar.

As know that acceleration is proportional to velocity.change in velocity leads to change in acceleration.once bumper and frontal portion deforms crash increases so acceleration increases.Maximum acceleration observed on left and right side is 11.776 mm/ms2 and 11 mm/ms2 respectively.

CONCLUSION

• the simulation of the neon frontal crash is run and impact or crash is analyzed at the various cross sections force and also the intrusion measured.
• Type 7 interface is created with recommended values.
• initial velocity applied in positive x-direction.
• rigid wall created with friction 0.1 and d_search of 1000.
• mass distribution were done by taking a 300k model as reference to match its center of gravity so there might be change that mass distribution on the left and right side is uneven due to which uneven sectional forces are observed on both sides.
• center of gravity also plays an important role in the crash analysis.it is an important concept in determining the stability of a structure .positions of the cog plays a vital role in having proper distribution of force on model.
• the kinetic energy is reduced because it is converted into internal enegy.the energy error ,mass errror and hourglass energy are under the acceptable values.
• Cross sectional force at left A piller 5.5 KNand on the right A-piller is 5.2 KN
• Cross sectional force at left rail 18 KNand on the right side is 14 KN
• .acceleration by b-pillar is 11.776mm/ms2.
• The dash wall intrusion at node 66695 is 150mm and at node 66244 is 140mm.