Challenge

Week 11 Car Crash simulation

OBJECTIVE:

The main objective of this challenge is to perform explicit dynamic analysis of a car body and to perform a parametric study using 3 different values of thickness such as 0.3mm, 0.5mm and 0.6mm for the car body. To apply the same conditions as mentioned in the video and to analyse the total deformation and Equivalent stresses acting on the model.

INTRODUCTION:

A crash simulation is a virtual recreation of a destructive crash test of a car or a highway guard rail system using a computer simulation in order to examine the level of safety of the car and its occupants. Crash simulations are used by automakers during computer-aided engineering(CAE) analysis for crashworthiness in the computer-aided design (CAD) process of modelling new cars. During a crash simulation, the kinetic energy, or energy of motion, that a vehicle has before the impact is transformed into deformation energy, mostly by plastic deformation (plasticity) of the car body material (Body in White), at the end of the impact.

Data obtained from a crash simulation indicate the capability of the car body or guard rail structure to protect the vehicle occupants during a collision (and also pedestrians hit by a car) against injury. Important results are the deformations (for example, steering wheel intrusions) of the occupant space (driver, passengers) and the decelerations (for example, head acceleration) felt by them, which must fall below threshold values fixed in legal car safety regulations. To model real crash tests, today's crash simulations include virtual models of crash test dummies and of passive safety devices (seat belts, airbags, shock absorbing dash boards, etc.). Guide rail tests evaluate vehicle deceleration and rollover potential, as well as penetration of the barrier by vehicles.

PROCEDURE:

Open the ANSYS Workbench software. Under the Analysis system select the Explicit Dynamics and wait for few seconds to pop up the window, which contains Engineering data, Geometry, Model, setup, Solution and Results.

Wait for few seconds and ANSYS Mechanical will open as shown below. Rename the model as Wall and Car body

SYMMETRY: Insert a symmetry to the wall and car. Insert the symmetry region and select the face of the wall. Similarly again select the symmetry region and select the edges of the car body as shown below.

Assign the material to the model. Right click on engineering data and under engineering data sources select explicit materials and assign Stainless steel (NL) to the car body, and a thickness of 0.3mm. Structural steel for wall as default.

In ANSYS automatic mesh will be performed with Default mesh size, so insert method and select the wall and choose method type as tetrahedranes and select the sizing option, select the face of car body as shown below, and also insert a method and select the car body and choose method type as triangles.

Mesh

Fixed support: Insert a fixed support to the car body and select the face as shown below.

Displacement: Insert the Displacement and select the back side face of the wall as scope and a magnitude of 500mm in Z-direction.

Analyasis setting

Now request for the outputs such as equivalent stress, equivalent elastic strain, Total deformation and directional deformation Z-axis.

We have to test the model with three types of thickness (i.e. 0.3mm, 0.5mm and 0.7mm, 1mm, 2mm) so select the box as shown below in order to activate the parameter set.

Results:

Total Deformation.

Directional Deformation.

Equivalent stress

Parametric sett results

We can view the simulations by making the respective thickness as set to current.

CONCLUSION:

From the above results we can conclude that the Highest equivalent stress of 8359.5MPa is experienced, when the thickness of car is assigned with 0.7mm. The Lowest equivalent stress of 8352.9MPa is experienced, when the thickness of car is assigned with 0.3mm. The equivalent elastic strain remains almost same in all three conditions. The Highest Total deformation of 999.68mm is experienced, when the thickness of car is assigned with 0.3mm. The Lowest Total deformation of 991.3mm is experienced, when the thickness of car is assigned with 0.7mm. From the above statement we can say that the increase in thickness will reduce the rate of Total Deformation generated.

SIMULATION RESULT:

For the car body thickness of 0.3mm

Directional deformation

Ship work like this
in your own course.