Week - 9 Material Modeling from Raw Data

OBJECTIVE:

• Use the graph digitizer to extract data of True stress vs true strain of anyone grpah given below
• Use this data point and creta a MAT_24 PIECEWISE LINEAR ELASTICITY material card for an elastic -plastic material.
• Verify the model card by performing a uniform tensile test on a dogmen specimen.

THEORY:

Material modelling plays an important role in determing the accuracy of simulation result and that it is a vaery important task in CAE industries.Team work on extracting the data from actual experiment or past available resource and turn them into solver accepted material card.

Usually multiple test are done and the data obtained from these test are either avergaed out or the best data curve is taken up for further processing around 150 to 200 data points are selected as a raw data.The raw data is filtered data off the noise present.

Now the data obtained after procesiing is usually taken as a curve input for material card we will follow a asimilar procedure for our excercise.

PROCEDURE:

DEFINE_CURVE for MAT_PIECEWISE_LINEAR_PLASTICITY.

The given Dogmen specimen.

Create SET_NODE for Left side of tensile test.

Also, the BOUNDARY_SPC

Spc_neutral for the tensile test.

The prescribed_motion _set. for Right side of tensile

CONTROL_IMPLICIT _GENERAL -----IMFLAG=1:DTO=0.1

The DATABASE_BINARY---STRFLG=1---Activate it

The DATABASSE_BINARY_D3PLOT----DT=0.1

Create SECTION_SHELL for tensile test.

Create MAT_PIECEWISE LINEAR PLASTICITY ---for steel

DEFINE_CURVE for effective stress and strain

The curve is generated for effective stress and strain

Create Load curve for PRESCRIBED MOTION SET.

The X-STRESS of final simulation

The VON-MISES STRESS.

X-STRESS

RESULT

The final simulation

CONCLUSION:

• From the above we learned the process of modelling material in LS-DYNA from the available test sample/data.
• Also we saw the variation in the simulation data,which is due to the lack of information like density of raw data.this variation can be fine-tuned by different value of these properties