Simulation of Crash Box using LS DYNA

OBJECTIVE :

To simulate a crash test for a crash box for which mesh is given. A crash box is a highly energy absorbing structure that crashes on application of loads and reduces impact on other components nearby. A full-fledges crashbox is a highly sophisticated design but in this case we will go with a rectuangular channel which can thought of as the most simple crashbox.

PROCEDURE :

CREATING RIGID FLOOR:

Create Entity -> Rigidwall -> Create -> Planar -> Normal to Z -> Select an element in the srface for which plane has to be created.

Select -> Create -> Planar -> Select a Node to which the plane should be Normal -> Translate ->Done

The Rigid floor is here created as shown.

CREATING SECTION :

SECTION -> Select Solid (As Mobile is an solid defined part)

Input Section ID adn Title, which should be unique.

APPLYING MATERIAL PROPERTIES :

Select 24- Piecewise Linear Plasticity

Material Properties for Aluminium Frame with unit consistency of mm | mg | gm

ETAN is given approx of (2-10% Youngs modulus)

APPLYING VELOCITY :

Initial -> Velocity

potential drop due to gravity, v=√2gh

here, we consider it as forced drop, in which the velocity is taken as -13.88mm/ms

SIMULATION TERMINATION:

Control -> Termination Time

End Time is given as 12.00

DATABASE SPECIFICATION:

ASCII_Option:

In this Time output between intervals is specified as 0.08

for the following output Requests,

D3PLOT

Resultant Interface Forces (RCFORC)

Global Statistics (GLSTAT)

Sliding Interface Energies (SLEOUT)

BINARY OUTPUT:

In this Time output between intervals is specified as 0.08

.

INITIATING SIMULATION:

-> Open LS-RUN

-> Input file -> Select the keyword file of the Drop test

-> Run the Simulation

REPORT SUMMARY OF SIMULATION WINDOW:

SIMULATED DROP TEST : (LS-RUN)

SECTIONAL PLOT :

- The crash box has experienced a stress of about 85N

ACCELERATION PLOT :

- The acceleration of the crash box is of is about 4

STRESS :

- The stress is about 100

STRAIN :

- Strain is not produced in the crash box

- From the graph it is visible, that the crash box is not under going deformation, hence it remains 0

ENERGY PLOTS:

- Kinetic Energy is about 0.04

- Internal Energy is about 0.08

- Total Energy is of 0.11

- Hour glass energy is about 0.005

- The Sliding Energy is of 0

1.5mm Thickness :

Input Section ID adn Title, which should be unique.

APPLYING MATERIAL PROPERTIES :

Select 24- Piecewise Linear Plasticity

Material Properties for Aluminium Frame with unit consistency of mm | mg | gm

ETAN is given approx of (2-10% Youngs modulus)

APPLYING VELOCITY :

Initial -> Velocity

potential drop due to gravity, v=√2gh

here, we consider it as forced drop, in which the velocity is taken as -13.88mm/ms

SIMULATION TERMINATION:

Control -> Termination Time

End Time is given as 12.00

DATABASE SPECIFICATION:

ASCII_Option:

In this Time output between intervals is specified as 0.08

for the following output Requests,

D3PLOT

Resultant Interface Forces (RCFORC)

Global Statistics (GLSTAT)

Sliding Interface Energies (SLEOUT)

BINARY OUTPUT:

In this Time output between intervals is specified as 0.08

.

INITIATING SIMULATION:

-> Open LS-RUN

-> Input file -> Select the keyword file of the Drop test

-> Run the Simulation

REPORT SUMMARY OF SIMULATION WINDOW:

SIMULATED DROP TEST : (LS-RUN)

SECTIONAL PLOT :

ACCELERATION PLOT :

STRESS :

STRAIN :

- From the graph it is visible, that the crash box is not under going deformation, hence it remains 0

ENERGY PLOTS:

- Kinetic Energy is of about range droping from 0.06

- Internal Energy is about 0.1-0.08

- Total Energy is about 0.14

- Hour glass Energy is of 0.008

- The sliding energy remains 0

COMPARISON :