Week - 4 - crash box simulation

G drive: https://drive.google.com/drive/u/0/folders/1S18pT4BTUAOJ-_CcfmpdcvvKG5dY2Guq

AIM:

To perform and creating the rwall and creashing the rectangle box in rigid wall with basic file .k and from that obtaing the various simulation result and comparing with the variable thickness box such as 1.2mm and 1.5 mm with elastic material cars and non-linner material card

MODEL SETUP

From this model they given maintain the gm,mm,ms unit system

Base set up of Keywords

• Material creation
• section creation
• Part defination
• Contact defination
• Velocity assign
• Control defination
• Output request(data base)

MATERIAL CREATION:

Before creation of the materials what are the parts list available to find that goto>model and part>part data. has seen the it contain shell part as the name can change in crash box

here we consider the the box as made up of steel so,take stell material property

MATERIAL PROPERT OF STELL

------------------------------------

PROP	VALUES
DENSITY(Ro)	0.0078500
YOUNG MODULAS	2.1E5
POSSION RATIO(PR)	0.3
YEILD STRESS(SIGN)	350
TANGENT MODULAS(ETAN)	1E4

Here we consider the box material is 24_mat_piecewise_liner_plasticity

section creation

We know that the box as shell formulation so we assign the elform is 2 and the thickness=1.2mm

Part defination

The craeted sectionansd material are assign the box part

Boundary setup

For in this simualation we know that the box is hit higly strong rwall(rigid wall) so we want create the rigd wall in order to do that goto>create entity>rwall>create>planer>1n+NL

As the rwall is 15mm away from the crash box

Contact defination

As we know the box is crashing the rwall so,there no contact penetration occur between the box and rwall so, we don't want create the contact defination for rwall but the box is contact himself so, we need to create the contact AUTOMATIC_SINGLE_SURF

VELOCITY ASSIGN(goto>create entity>Intial>velocity)

The box is moving the -13.88 mm/ms with iinclude of gravitnational force also

SET_CRAETION

We want the what is the force cration in middle of the moiddle box so that we want first create the SET_NODE and SET_ELEMENT in create entity

CONTROL TERMINATION

• *cotrol_accuracy=Define control parameters that can improve the accuracy of the calculation. where osu=1(objective stress updates) and inn=2(On for shell and thick shell elements (default for
  implicit))
• *control_energy=Provide controls for energy dissipation options. where HGEN=2(Hourglass energy calculation option),RWEN=2(energy dissipation is computed and included in the
  energy balance ),SITEN=2(energy dissipation is computed and included in the energy balance),RYLEN=2(energy dissipation is computed and included in the energy balance.)
• *control_hourglass=Redefine the default values of hourglass control type and coefficient. where ihq=4 is control the hour glass and qh=0.1
• *control_termination=Stop the job. dt=5ms
• Thses are the control cards are applied

OUTPUT REQUEST OR DATA BASE CARDS

• ASSCII=>SLEOUT,RCFORC,NODOUT,MATSUM,GLSTAT,ELOUT
• BINIARY_D3=This keyword is used to request binary output,Database for entire model.
• CROSS_SECTION_SET

POST PROCESSOR

CASE-1 THICKNESS 1.2mm-EFFECTIVE STRESS

As we seen the image is effective von mises stress at time=1ms this the time step only the box hit to the rwall and that the wall resist the force so, there is some force is produce that is the stressthe intial stress is very hig becasue the velcoity is hign and the onther reson is the force is not penitrate with wall in image the red region are higly stress area the stress value is 410. and in second image the with decribe the effective stress in at time step int=5ms and the value are 321.216 the reduction stress is indicate the stress is distributed along the part so, that there is a stress reduction

CASE-2 THICKNESS 1.5 mm

As we seen the image case -2 thickness 1.5mm with same material propertybut the thickness is varying the from 1.2 to 1.5 for that t=5 the stress is 312.34 but the t=1.2mm and time=5ms the stress is=321.216 so, the thickness of 1.5mm box with obtain the less stress when comparing the 1.2mm box

CASE-1 THICKNESS 1.2mm-EFFECTIVE STRAIN

The strain is nothing but the changing lenght from above image we seen the box contact with the rwall with the time step t=1ms at time the strain is 0.0059077 and the time step 5 and the strain is 0.0096 from dur the impact the material molecules are geting vibration and there is some small deformation occur in the along length the deformation and the total deformation is 0.0096 at the end of the time step=5

CASE-2 THICKNESS 1.5 mm-EFFECTIVE STRAIN

The strain is nothing but the changing lenght from above image we seen the box contact with the rwall with the time step t=1ms at time the strain is 0.00585116 and the time step 5 and the strain is 0.008604 during the time the material are defomation occur.and there is some small deformation occur in the along length the deformation and the total deformation is 0.00860 at the end of the time step=5

CASE-1 KE vs IE(thickness-1.2mm)

Internal energy is defined as the energy associated with the random, disordered motion of molecules. It is separated in scale from the macroscopic ordered energy associated with moving objects; it refers to the invisible microscopic energy on the atomic and molecular scale.As we seen the graph crash box IE and KE time 0 the energy also 0 which indicate there no energy dissipation between box andrwall but time 1 there is contact hapening between the box and wall so, that the energy dissipation occur so,that internal energy of the box is increased after some time it come the more over constant i.e after impacting the box is bounce so the stress is evenly distrubuted around the box

the kinetic energy (KE) of an object is the energy that it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes.in the same way but the energy dissipation happening for kinetic energy

CASE-2 KE vs IE(thickness-1.5mm)

CASE-1 TOTAL ENERGY T=1.2mm

The total energy is sumof the all energy i.e KE,IE,HE etc.. the hour glass energy is constant because of the we use the IQH=4 which indicate there is no zero stress when the force is acting the nodel point

CASE-1 TOTAL ENERGY T=1.5 mm

CASE-1 SECTION FORCE XYZ T=1.2mm

CASE-2 SECTION FORCE XYZ T=1.5mm

ACCLEARTION ALONG THE LENGTH DIRECTION AT 1.2MM

DIRECTION	VALUE MIN at T=5ms in mm/ms2
X	3453.43
Y	2224.98
Z	1527.58

ACCLEARTION ALONG THE LENGTH DIRECTION AT 1.5MM

DIRECTION	VALUE t=5 inmm/ms
X	4502
Y	1596
Z	1568

RESULT COMPARISION CHART STRESS,STRAIN,

------------------------------------------------------

S.NO	NAME	T=1.2(time=5ms)	T=1.5(time=5ms)
1	STRESS	321.216	312.34
2	EFFECTIVE PLASTIC STRAIN	9.604e-3	8.605e-3
3	ACCLEARTION ALONG X,Y,Z	3453.43, 2224.98, 1527.58	4502,1596,1568

CONCULSION

• As we seen the result comparison chart we decide the 1.5 mm box which having produce the less stress when we comparing the 1.2mm as same that the effective plastic strain also due the less amount of increasing the thickness the force action also varying
• Through this assignment we learn the how to do the rwall and how give the property of contact
• Through this assignment we learn the how apply the velocity, hourglass,control cards etc..
• Through this assignment various type enegy dissipation curve are leared.