Week-6 Calculate the Stretch Ratio by comparing the ELFORM (-2,-1,1,2) with Ogden_Material Model.

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

Aim:

To given hyperelastic material testing the uniaxile test(tensile test)along the x direction and the plot the graph engineering stress vs stretch ratio in various element formulation.and the testing is conduct the implicit method

What is explicit method of analysis

At each nodal point the internal and external force is assumed and the acceleration at the node is computed using the F=M*A.so,integrating the acceleration in time velcoity the displacement are calculated and the solution is advanced at time

assumes constant acceleration over time step

change the geomentry depends only on to the known quantites from previous step

conditionly stable and capable to slove the exterme non-liner

short duration and highly transient

What is implicit method of analysis

A global stiffenes matrix is computed and inverted applied to the node out of balance force to determine the displacementF=K*u

assumes acceleartion varies linerely over time step

change in geomentry depands on the unknown quentites in current step

unconditionaly stable and can have problem with the non linerity

Model setup

Creating the model

assign the material and section

apply the boundary condition

adding the essitinal keywords in implicit analysis

post processor result and ploting the graph

Creating the model

assign the material and section

apply the boundary condition

1.boundary condition are created such as x-direction all transtional constrient

2.center horizontal line boundary condition are created such as y-direction all transtional constrient

3.vertical line boundary condition are created such as z-direction all transtional constrient

adding the essitinal keywords in implicit analysis

*CONTROL_IMPLICIT_AUTO

Define parameters for automatic time step control during implicit analysis

*CONTROL_IMPLICIT_GENERAL

Activate implicit analysis and define associated control parameters. This keyword is required for all implicit analyses.

*CONTROL_IMPLICIT_SOLUTION

These optional cards apply to implicit calculations. Use these cards to specify whether a linear or nonlinear solution is desired

*CONTROL_IMPLICIT_SOLVER

These optional cards apply to implicit calculations. The linear equation solver performs the CPU-intensive stiffness matrix inversion

runing the simulation

the complete Analysis is eqiberilium and normal termination

True strain = ln(1 + engineering strain)

engg.strain=exp(true strain)-1

True stress = (engineering stress) * exp(true strain) = (engineering stress) * (1 + engineering strain)

engg.stress=true stress/streatch ratio

GRAPH

ELFORM-1

ELFORM-1

ELFORM 2

ELFORM-2

Conculsion

in this assignment we learn the what is implicit analysis and importent keyword crds

And what is true stress and engg stress and etc..