crash box crash test simulation

AIM : To create simulation of Crash Test for a Crashbox striking Rigid wall by using LS DYNA.

OBJECTIVE :

• Import the keyword file provided with elements and nodes into LS Pre-Post.
• Create the keyword cards as per requirement and include the data given.
• Check for the errors in Model check for Keyword cards error and then save the file as in (.k) type.
• Run the saved file in the LS DYNA manager.
• Open the results files in LS Pre-Post for Resultant data of Crash Test.

PROCEDURE :

given data : Units are to be taken in gm/mm/ms

Material taking STEEL : density = 7750 kg/m^3 = 7.75 * 10^-3 g/mm^3

Youngs modulus = 180 Gpa = 180 * 10^3 Mpa

poison's ratio = 0.30

SIG Y = 314 Mpa

E Tan = 9000 Mpa

Velocity = 50 KMPH = 13.88 mm/ms.

• first of all we have to import (or) open the provided (.k) file in LS Pre-Post and check for the keyword data provided in keyword manager.
• now, go to Model tools and in that we have to go to Create Entity tool to create the Rigid wall. select the type of wall and the start point of the wall.
• now, we have to go to Keyword manager to fill the required values to active the Rigid wall card.
• In the below image you can see the related image of procedure
  

• now we have to create the material card, for that we are taking MAT 24 PIECEWISE LINEAR PLASTICITY card as per the material behavior requiremnet.
• as per the given material ahs to be taken as STEEL , we filled up the STEEL material properties in the card and accept it.

• As per nature of elements required we are providing the elements as SECTION SHELL with the following thickness provided as 1.2mm and 1.5mm respectively for two different tests.

• now we have to provide the velocity card to the crashbox, which helps to define the speed of crashbox towards the rigid wall for crashing.
• we have to go to keyword manager > initial > velocity. in which we have to provide the set of nodes which are going to move with the velocity.
• the unit conversion is done in mm/ms and the rigid wall is placed in the -X direction to the crashbox. so,that we are taking values as -13.88mm/ms.

• as of now, we have been created the material and section card for the part.now we have to assign them to part.
• for that we have to go to keyword manager > part.
• In which we have to select the material id and section id , which we created as per the requirement.

• now , we have to provide the main part of the test which is Control Termination card. which helps to define the duration time of the test to be run.

• now we have to provide the output data cards with the time span value in which the data has to be written.
• the required data output files for this Crash Test as per the requirements are D3PLOT , GLSTAT, SLEOUT, RCFORC, NODOUT, RWFORC & SECFORC.
• the given time span to written data is 0.1 ms.

• check for the keyword error in model check tool , if no error is present then we have to save the file in (.k) format.
• after saving the file, go to the location of the file and open it in notepad c++ , to check for the data in coding format and from here we can change the card id name and titile name.
• in the below image you can see the following step.

• now save and run the file in LS Manager and wait for the process to complete.
• as shown in the below image , if your file ends by showing normal termination then there is no error present.

RESULTS :

For the results the output data file has to be open in the LS Pre-post. the simulation is done with the given data as per the requirement with both the thickness as 1.2mm and 1.5mm.

the simulation animation video is provided through the link below and also the (.k) crash test file is also shared with the link below for the further references.

https://youtu.be/u6Vqq_ywVyw for 1.2mm thickness crashbox

https://youtu.be/JC7H-MAKRns for 1.5mm thicknes crashbox

https://1drv.ms/u/s!AnGsOah9scM2f181ccmh7PjLwCs?e=WGnbAq for (.k) files

the output data are plotted in the below to make a comparisson of test with both the thickness of 1.2mm and 1.5mm of crashbox. as per the plotted data you can observe the changes in the follwoing data of directional stresses induced , acceleartion and cross-sectional force in the middle of the crashbox.

• CROSS - SECTIONAL Force generated in the middle of CRASHBOX

• GLOBAL STATICTICS DATA OF THE CRASHBOX with Energies

• ACCELERATION PLOT of NODES in the middle of CRASHBOX (Top view node 199) and (Left view node 7525)

• DIRECTIONAL STRAIN INDUCED AT THE MIDDLE OF THE CRASH BOX.( S 7312 shell element from top and S 1174 shell element from left view)

• DIRECTIONAL STRESS INDUCED AT THE MIDDLE OF CRASHBOX ELEMENTS .( S 7312 from top and S 1174 from left view )