bEakerPPK
Aerospace
- Dec 14, 2007
- 11
Hi everyone,
I've scoured the archives and documentation regarding this and have done my best to avoid starting a thread but alas, I need some help here.
My situation is that of implementing a uniform residual stress (no depth profile through the thickness) into a hybrid laminate (tensile for constituent 2024-T3 aluminum and compressive for S2-Glass fibres - a result of the curing process for those interested). It seems that the way to go here (according to the archives) is the use of the SIGINI user subroutine, which is fine (admittedly I'd be new to user subroutines but I suppose SIGINI is a good one to start with) but it creates a few python issues:
1) I still need to specify *INITIAL CONDITIONS, TYPE=STRESS, USER in my input file. How do I do this in my python script? The documentation is not so hot on this and I certainly hope it's not a myModel.keywordBlock.replace sort of solution which I am not that big a fan of.
2) Since there would be two different residual stress values on two different regions of the model can I implement both of them into a single SIGINI? Likely not, if so, can I have more than one of these subroutines? Moreover, do the initial values have to be strictly placed on an element set or can I do it onto a geometric region (analogous to specifying cells with the findAt command)?
3) Do these initial conditions apply to the default "Initial" step? The documentation recommends that I include an additional step to ensure that equilibrium is achieved before any contact or load steps are created (totally a good idea, since I am doing both of the aforementioned) but it is unclear about whether or not these "initial" conditions apply to the "Initial" step or to the newly created step, let's call it the "residual stress" step. Also, are there any consequences to specifying the initial increment size equal to the total step size (as recommended)? I fear the introduction of negative eigenvalues through the onset of material instability if the step size should be so large.
4) Is there a difference if I apply this to C3D8I incompatible mode elements vs C3D8R reduced integration elements? It doesn't seem like it would matter, but I'm not sure....
5) Is there any way I can use a free compiler to get this show on the road? (I'm using 64-bit Vista <groans> , I know, I know, it wasn't my choice, we can save the rebuke for another time)
Please let me know what you think. Any insight is greatly appreciated here; I'm at the tail end of this portion of my analysis and thought I'd kick it up a notch with this...I am up for the challenge.
Thanks in advance!!!
I've scoured the archives and documentation regarding this and have done my best to avoid starting a thread but alas, I need some help here.
My situation is that of implementing a uniform residual stress (no depth profile through the thickness) into a hybrid laminate (tensile for constituent 2024-T3 aluminum and compressive for S2-Glass fibres - a result of the curing process for those interested). It seems that the way to go here (according to the archives) is the use of the SIGINI user subroutine, which is fine (admittedly I'd be new to user subroutines but I suppose SIGINI is a good one to start with) but it creates a few python issues:
1) I still need to specify *INITIAL CONDITIONS, TYPE=STRESS, USER in my input file. How do I do this in my python script? The documentation is not so hot on this and I certainly hope it's not a myModel.keywordBlock.replace sort of solution which I am not that big a fan of.
2) Since there would be two different residual stress values on two different regions of the model can I implement both of them into a single SIGINI? Likely not, if so, can I have more than one of these subroutines? Moreover, do the initial values have to be strictly placed on an element set or can I do it onto a geometric region (analogous to specifying cells with the findAt command)?
3) Do these initial conditions apply to the default "Initial" step? The documentation recommends that I include an additional step to ensure that equilibrium is achieved before any contact or load steps are created (totally a good idea, since I am doing both of the aforementioned) but it is unclear about whether or not these "initial" conditions apply to the "Initial" step or to the newly created step, let's call it the "residual stress" step. Also, are there any consequences to specifying the initial increment size equal to the total step size (as recommended)? I fear the introduction of negative eigenvalues through the onset of material instability if the step size should be so large.
4) Is there a difference if I apply this to C3D8I incompatible mode elements vs C3D8R reduced integration elements? It doesn't seem like it would matter, but I'm not sure....
5) Is there any way I can use a free compiler to get this show on the road? (I'm using 64-bit Vista <groans> , I know, I know, it wasn't my choice, we can save the rebuke for another time)
Please let me know what you think. Any insight is greatly appreciated here; I'm at the tail end of this portion of my analysis and thought I'd kick it up a notch with this...I am up for the challenge.
Thanks in advance!!!