TITLE: CALCULATE THE STRETCH RATIO BY COMPARING ELFORM(-2,-1,1,2) WITH OGDEN MATERIAL MODEL.

OBJECTIVE: TO PERFORM A TENSILE TEST ON A CUBE MODEL(10mm X 10mm X10mm) AND COMPARE THE STRETCH RATIO FOR DIFFERENT ELFORM.

PROCEDURE:

• Creating mesh model.
• Defining the boundary conditions.
• Defining the section and material.
• Defining the control cards.
• Defining the database cards.

Creating the mesh model.

Model of 10 x10 x10 (mm) is created used mesh option.

ASSIGNING THE SECTION AND MATERIALS.

• Here solid section card is used and ogden rubber is used as material.

DEFINING BOUNDARY CONDITIONS.

• SPC set is constrained by three sets,in 1st set of nodes only Y direstion is contrained,in horizontal set of nodes z is contrained and in vertical set of nodes X is constrained.These SPC are defined such that when tensile force acts on the nodes such that all the contraction and elongation happens.
• Displacement is given to the set of nodes in golbal Y direction sch that all the elements diaplaced towards Y direction.

CONTROL CARDS:

• Implicit general is used to run the simulation in implicit solver.
• Implicit auto is used for automatic time step control in solver.
• Termination card is used to define the end time.

DATABASE CARDS:

• Exent binary card is get the strain data from the simultion.

CALCULATIONS:

TRUE STRESS AND ENGINEERING STRESS

`sigmat=sigma(1+epsilon)`

`sigma=(sigmat)/(1+epsilon)`

TRUE STRAIN AND ENGINEERING STRAIN

`epsilont=ln(1+epsilon)`

`epsilon=e^(epsilont)-1`

STRETCH

`lambda=epsilon+1`

RESULTS:

PLOTS:(X-STRETCH,Y-ENGG STRESS)

ELFORM (-2)

ELFORM(-1)

ELFORM(1)

ELFORM(2)

• This plots shows the behaviour of diffrent ELFORM.
• All the plots are more or less similar to eath other no such obsevations or difference can be seen.

CONCLUSION:

• tensile test is done on a cube block of ogden material model.
• implicit solver is used in order to achive more accurate results.
• Data obtained from Lsdyna are in true values of stress and strain therfore they are converted to engineering stress and strain.
• Stretch is obtained using engineering strain value and graph is plotted between stress and stretch.