I think I have created a simple scene of my IrisDoor or at least it looks like it.
I have managed to seperate each of the plates of the door to layers of their own. I also have a layer which contains an octagon that is used to position the door plates in an open position. There is also a feable attempt to create a wall layer to overlay the plates, still working on this one.

The trick now is to create an animation starting from the closed position (this is where the plates are currently) to an open position. The idea here is to go to the end sequence time mark (60secs) and position each of the plates on each layer to their respective open position. Then let the model generate the movement over that 60 seconds.

Where do I start this? Any help or suggestions would be great.

If you would like to see the article I am trying walk-through, I have uploaded to my office live spaces site. Please take to to look at them for an understanding of what I am try to do.
http://cid-54757514a9aa34b2.office.live.com/browse.aspx/Public

Could you perhaps add one or two screenshots of your model (as most of us cannot open the file format you're using - it's restricted to the Mod Tool & can't be opened in the regular version of Softimage AFAIK)?

edit: BTW - is this intended for export to a game engine? If so, which?

Ok, this is what i have so far. This is just the scene file. I am not sure how to clean it up or if it is done right.

I think thats better, with Expression

Ok simple walkthrough of what I have already.

I am using NURBs to set to first triangle as follows: Snap to grid on, assuming (X, Y, Z) coordinates, first POINT at (0, 0, 0), next at (-10, 0, 0) and third at (-10, 10, 0). This completes the initial or first plate. Now we have to create 7 more in a 45 degree radial with center point at (0, 0, 0).

This was done as such: Select the Polygon just created, “Modify”, then “Poly. Mesh”, “Extrude along axis”.
Adjust the dialog box as follows:
On the Extrude Tab:
Length = 0,
“Duplicate Polygons” checked,
Inset amount 0 (zero),
X, Y, Z unchecked,
Select Frame Object,
Merge Check (not sure what this does),
Subdivs 6
On the Transform Tab:
Check “Transform Per Subdivision”,
Set Scaling (1, 1, 1),
Set Rotation (0, 0, 45),
Set Translation (0, 0, 0)

This completes the design or model of the 8 plates for the door, in the closed position. Unselect the objects.

Now add a new Layer, this is used for the positioning of the door plates to the open position. Hit the #6 key, “Layers” menu “New Layer…” and name it Octagon, it does not matter. Now select the new layer and place NURBs at the points of the triangles where they meet to form a 90 degree angle, starting at any point and go either clockwise or counter-clockwise to create an octagon. This will represent the edges of the opened door. But first we need to rotate it on the Z axis 22.5 degrees. Set the Z value for rotation to -180; basically add 22.5 to the number to the Z value. Unselect the object. You should end up with this.

My question now is should each of the plates be a seperate Layer? If not and they can all exist on one layer then how do you create keyframes to go from the closed position to the open position?

Ok, I think I have managed to get the effect I was going after. I do not know if this is the correct way to do it, but it appears to function.

Check it out and let me know what else is needed or to be cleaned up.

Now the next step is to be able to add a texture to it. This may be a challenge or a bit tricky, since I would want a basic square texture that would cover the Door Frame. This was another layer used to scope how the door would look when opened. Each of the panels would need to have its portion of the texture applied and retained during the opening. That way it could be hidden or obstructed in some way during game play if needed.

Could you please explain what's wrong with the solution Janosch posted?

OK, can't open this scene in 2011....

but, do you want the triangles to "slide" on one another or is it ok if they cross one another? The above expression by Janosch seems to do what you want unless you want them to 'slide' on one another. I am pretty ignorant when it comes to expressions so I can't really try and figure out how to adjust or change the expression Janosch used to make them slide... but this may be what you want.

I was able to open the scene but there was no animation, secondly the plates are to slide on the others sides so that there is no over-lap. I could not figure how to use expressions either.

I was able to get the effect I desired by creating 8 layers, one for each of the plates and moving them in one keyframe.

I am suprised you cannot open the scene.

Now I have to figure how to texture the plates.

The idea is for them to slide on each others side at a 22.5 degree angle. I am working on an animation avi so you can see what I have done.

So now I have to understand texturing and apply a texture to the plates.