Learning Forum

[andrea.madonia]

Goodmorning, I need to simulate a material with a non linear elastic stress strain curve. nI have a uniaxial stress strain curve from lab test (vd. figure) with a yield strain of 12% and yield stress of 28 MPa. Lab test result gives an elastic modulus of 990 MPa while calculated one is E=28/0.12=233 MPa. Because I am intersted also in plastic behaviour, if I use 1090 MPa component will be stiffer and material does not yield and if I use 233 MPa material will deformate more than real application (probably, because is a bending like analisys).nCould Ansys manage non linear elastic behaviour like displayed one?.Thanks and excuse for my english.nn

[1shan]

,nPlease check this video on how to define a plasticity model in ANSYS

. I believe the 12% strain is of the specimen and not the base material right? For example Aluminum Honeycomb structures have similar stress strain behavior to what you have shown. This means that 12% is the bare compressive strain of the aluminum honeycomb structure not of aluminum. You need to input the non linear stress strain data for aluminum, apply it to the honeycomb structure and once you simulate crushing you can get the above graph as a result.nRegards,nIshan. n

[andrea.madonia]

Tested material is a termoplastic resin. Looking at attached plot, I can use the orange behaviour (understimate material stiffness) or the purple one (overstimate material stiffness). nQuestion is: can Ansys manage bilinear (or multilinear) elastic curve (not plastic)?n

[peteroznewman]

nThe file you attached is shown below. Don't attach, do insert the image if you want Ansys staff to see it. They are not permitted to open attachments.nIn the lab, if you took the material up to a strain of 0.11 and then reversed back down to zero, would the material elastically recover? That is what you seem to be asking. There is a long list of hyperelastic material models that can exhibit nonlinear elastic stress-strain curves. But those materials don't have a yield point. Then there is a list of visco-elastic material models which include a permanent flow of material.nWhat is you application for this material model? Do you need to operate in the nonlinear elastic region or do you need to operate past the point of ultimate stress?n