FRP Material Property in ANSYS APDL

[hexa2016]

Hi,

I just have some doubts about assigning frp laminate.

The material property given is for 0.3mm frp laminate/layer. The final thickness is 1.2mm which consisted 4 layers.


I create FRP laminate as shell element in APDL;

sectype,2,shell
secdata,0.15,2,0,3
secdata,0.15,2,90,3
secdata,0.15,2,0,3
secdata,0.15,2,90,3
secdata,0.15,2,0,3
secdata,0.15,2,90,3
secdata,0.15,2,0,3
secdata,0.15,2,90,3

is it correct the way of assigning the frp material?


Thanks

 

[Erik Panos Kostson]

Not sure in your example because 4 layers are needed (0.3m each), with a total thickness of 1.2, but in the APDL commands, there are 8 layers with a thickness of 0.15 each.

The general structure of the secdata is:
secdata, thickness, material property nr, orientation (angle),integration points,
(repeated for each layer)

So say one has a stack of four layers, two layers with property number 1 (top and bottom layer), and with a thickness of 0.3, and two middle layers 90 degrees relative to the other two, with property number 2, and thickness of 0.2, then it would be:

sect,1,shell,,
secdata, 0.3,1,0.0,3
secdata, 0.2,2,90,3
secdata, 0.2,2,90,3
secdata, 0.3,1,0.0,3

(Perhaps in your case you need 4 layers that are 0.3 mm thick and not 8 0.15 mm thick layers)

Hope this helps

 

[hexa2016]

Thanks Erik for the reply,

Actually, I used bi-directional frp (0.3mm thk)with 0-90 fiber direction. So in actual work, it has 4 layers. In ANSYS APDL , since I need to include every angle of fiber direction, i divided it into 8 layers with 0.15mm each. This is because as far as i know, I can include only one angle at each secdata command.

please correct me if I am wrong?

Thanks

 

[Erik Panos Kostson]

You are welcome.

I see. I believe that it is only possible to have one direction/angle per ply layer.

In this case then, if the two 0.15 mm thick plies/lamina making up the bidirectional layer (0.3 mm), are on top of each other (two layers 0 and 90 degree say) then I believe that your proposed code (apdl code could be used. If not then it is not strictly correct (one could investigate the effect).

If they are not on top, one could define an orthotropic/ply material property for the bidirectional ply which has the different properties in the two different directions. As an example if the two fibres along 1 dir./0 degrees and 2 dir./90 degrees directions, are the same, then in this case E1=E2 for such a bidirectional ply. In any case one could use this even with E1 not equal E2. Finally then have 4 bidirectional layers (0.3 mm layer thickness), using these bidirectional based properties. Later one can define the ply strength properties in the different directions (the same in 1 and 2 in this example where E1=E2), which would be used to calculate the reserve factors for different failure criteria. Obviously with this approach one can not look for interlaminar shear failure within one ply. For the other approach if they are truly on top of each other, one could look on the shear failure within one ply since they are modelled by two 0.15 mm thick layers (0-90 degrees).

In any case I think it is good to try to model this bidirectional layer and the total laminate stack as it is (there are assumption in the models used by softwares, that are many times based on CLT, but that is another story).

It is a bit long, but I hope it makes sense.