Hello,
I have a couple of related questions regarding non-linear elastic orthotropic material properties. First, is there a way to input stress-strain data for such a material? The actual material I'm modeling is a knit polyester textile, and so far I've been using a Linear Orthotropic material property as a matter of convenience. I'm using ANSYS ver.8.0 (University license), and this is a static structural problem with the load acting transverse to the plane of the fabric.
Additionally, the material is very thin (.020" at the thinnest region) and any M.P. entries involving thickness (Ez, Gxz, etc.) have been grossly estimated. The stress-strain curves (from uniaxial tensile test data) in both principal directions could probably be approximated as bi-linear; the final slope is greater than the initial. I've been using the stiffer section of the curve, but was wondering how best to employ the material's changing stiffness (the entire curve) into the ANSYS model.
The closest non-linear material behavior option I could find in ANSYS Help that accepts stress-strain data is MELAS, but this requires elastically isotropic materials (Ex=Ey=Ez). Is there another option that allows input of a non-linear orthotropic material response curve?
Secondly, if I were to approximate this as bi-linear elastic orthotropic (if the first option is unfeasible), is it necessary to set up each linear M.P. set at a different temperature and change temp at a load step (I thought I saw something along these lines suggested in the archives)? Previously, I've attempted a 'bi-linear' approximation using MPCHG with a 2nd load step in SOLUTION, but I don't believe I've used this properly (the solution basically ignores the 1st material property and solves using the 2nd one).
Thank you for any assistance that may be offered.
I have a couple of related questions regarding non-linear elastic orthotropic material properties. First, is there a way to input stress-strain data for such a material? The actual material I'm modeling is a knit polyester textile, and so far I've been using a Linear Orthotropic material property as a matter of convenience. I'm using ANSYS ver.8.0 (University license), and this is a static structural problem with the load acting transverse to the plane of the fabric.
Additionally, the material is very thin (.020" at the thinnest region) and any M.P. entries involving thickness (Ez, Gxz, etc.) have been grossly estimated. The stress-strain curves (from uniaxial tensile test data) in both principal directions could probably be approximated as bi-linear; the final slope is greater than the initial. I've been using the stiffer section of the curve, but was wondering how best to employ the material's changing stiffness (the entire curve) into the ANSYS model.
The closest non-linear material behavior option I could find in ANSYS Help that accepts stress-strain data is MELAS, but this requires elastically isotropic materials (Ex=Ey=Ez). Is there another option that allows input of a non-linear orthotropic material response curve?
Secondly, if I were to approximate this as bi-linear elastic orthotropic (if the first option is unfeasible), is it necessary to set up each linear M.P. set at a different temperature and change temp at a load step (I thought I saw something along these lines suggested in the archives)? Previously, I've attempted a 'bi-linear' approximation using MPCHG with a 2nd load step in SOLUTION, but I don't believe I've used this properly (the solution basically ignores the 1st material property and solves using the 2nd one).
Thank you for any assistance that may be offered.
