Week - 9 Material Modeling from Raw Data

MATERIAL MODELLING FROM RAW DATA

OBJECTIVE:

              In this challenge we have to Use the diagram of the true stress-strain curve of graphite iron casting. Two curves are there for different material structures and we need to pick any one of them and use the data to create either a MAT_024 or MAT_018 material model and then validate it. 

PROCEDURE:

• First, we have to extract true stress and strain data from the give curve and feed that into excel.
• The given data unit is in Ksi so we have to convert that into Gpa and Kg mm ms.
• Then we have to plot the effective Plastic strain graph to import the stress strain data into Ls-prepost by the formula.

                Eff.plastic strain = True strain – (True stress/E)

• Then plot the eff.pls strain and stress graph and try to fit the curve with polynomial equation.
• Then extract the data from the fit equation to define the stress strain curve in Ls-prepost.
• Then create section for the dog_bone specimen.
• Then define the displacement curve and stress strain curve using the fit equation datas.
• Then create MAT_024 material card and assign the stress strain curve.
• For the boundary condition we have to constrain one node in all direction and then create a node set and constrain them in all direction except y so that the specimen compress in y-axis while expanding.
• Then create prescribed motion in opposite direction of spc and constrained in all direction except X-axis and assign the displacement curve to it.
• then assign the sec and MAT in part id.
• Then create control implicit_auto, implicit_general and termination card so that the stimulation run in implicit analysis.
• In database create extend_binary card and assign STRFLG as 1 so that strain value can be plotted.
• Then run the stimulation in Ls-Dyna solver.
• then extract stress and stran in X-direction and compare them with the raw data.

CONCLUSION

            Thus the validation of a material from the raw data is done, the below plot show the data from image and the stimulation are fit enough, the curve after yield point is consider as plastic region or hardening curve.