volume fraction of composite

[dyeyanie]

Dear Louise,

According to the above matter, I would to clarify a few criteria here in order to obtain a reasonable values of my composites. I have some unclear view on the parameter in yarn properties. Let say from the geometry, I have 28 nos of warps and 28 nos of weft and 0.3 for the height. is that means my RVE length in the warp and weft direction similar to 28 mm? what does the meaning of fibre per yarn? Is it similar to the meaning of Ends/cm per warp or picks/cm per weft layer? I hope there is the simplest way for me to varies the volume fraction in properties.

Yanie

[louisepb]

Hi Yanie,

The size of your RVE will depend on your yarn width and spacing. Assuming that you have specified your domain size to be that of your RVE then you can get the size from this. The default dimensions are mm.

The fibres per yarn gives the number of individual fibres within the yarn. In TexGen the yarns are modelled as solid yarns but, in reality, will be made up of a bundle of fibres. The fibre diameter etc refer to properties of the individual fibres from which yarn properties can be calculated. The functions within the CTextile class here http://texgen.sourceforge.net/api/class ... 75c41ac4e0 ( GetYarnVolume etc) can be used to calculate the accurate volume fraction. Which functions you use will depend on the data you have available.

Hope that helps,

Louise

[dyeyanie]

Dear Louise,

I have went through the code on volume fraction and I saw that there is an option on calculating the volume fraction according to what we put on the parameter. So I choose to insert the yarn linear density instead of areal density. Assume, the inputs are as follows;

Yarn properties
Yarn linear density = 600 g/km
Fibre density= 2580 kg/m3
fibre area = 2.325 e-6 m2
fibre diameter = yarn diameter = 0.8
fibre per yarn = 200
areal density = 0

Material properties
Y.Modulus = 2500MPa
v = 0.35
alpha = 0.000006 /K

However, I still got unreasonable values of volume fraction. Do this cause by the unit??

Some more, is there any "select all" options instead of picking one by one of this fibre for the yarn properties??

Yanie

[louisepb]

Hi Yanie,

If you select Yarn Properties in the Modeller with no yarns selected then the properties will be assigned to all yarns. Alternatively by using Shift + Mouse Click you can select multiple yarns and the properties will be assigned to the selection.

The fibre diameter is that of the individual fibres that make up the yarn. It isn't the same as the yarn diameter. Could this be where your error is coming from? Also note that the GetFibreYarnVolumeFraction function calculates the volume fraction of the yarn not the composite.

Louise

[dyeyanie]

Hi Louise,

Yeah, thanks for the 'bulb'!

Yanie

[dyeyanie]

Hi Louise,

Just to double check with you.

Is Fibre Area referring to the area of single fibre per yarn? Or it refers to area of cross section of yarn with corresponds to the no of fibres per yarn?

yanie

[louisepb]

Hi Yanie,

Fibre Area is the actual area of fibres within one yarn cross-section. So number of fibres x area of one fibre.

Louise

[dyeyanie]

Hi,

Ok, in order to get the volume fraction, do I need to put all the values for the characters? Because everytime I make changes, the previous values will replace the new one. So I get the same error again.

[louisepb]

Hi,

Sorry, I don't really follow your question.

Louise

[dyeyanie]

Hi Louise,

As I understand the computation of fibre volume fraction in a yarn is

fibre volume fraction = linear density of yarn (tex) / (fibre density * cross sectional area of yarn)

which means in your case the cross sectional of yarn is similar to Fibre Area. Is that correct? If this correct, I guess the easiest way to modify the volume fraction is by modifying the cross sectional area of yarn.


Please correct me if I'm interpreting your computation wrongly.

Yanie

[louisepb]

Hi,

If the cross sectional area of the yarn is the same as the fibre area then the fibre volume fraction will be 1. In TexGen GetFibreYarnVolumeFraction() calculates

fibre volume / yarn volume

Fibre volume is calculated in GetFibreVolume() using the yarn linear density.

Louise

[dyeyanie]

Hi Yanie,

Fibre Area is the actual area of fibres within one yarn cross-section. So number of fibres x area of one fibre.

Louise

Hi,

Is that mean in order to vary the fibre volume fraction, I just need to modify the yarn linear density values? How about the yarn volume??

I was explained that the fibre area is referring to cross sectional area of yarn correspond to my equation above. But not the same values as fibre area.

Yanie

[louisepb]

Hi,

If you modify the yarn linear density that will vary the yarn fibre volume fraction. You would have to change your model in order to change the yarn volume but that would also change the volume fraction.

Within TexGen the fibre area refers to the actual cross section of the fibres within the yarn. The yarn cross section is the whole area (eg an ellipse) which is used to model the yarns and is therefore different to the fibre area (unless, of course, your yarn is solid).

If you look at the TexGen functions you will be able to see how each value is used and hopefully that will clarify for you what each value is referring to and what each function calculates.

Louise

[dyeyanie]

Hi Louise,

I made some changes on yarn linear density and fibre areas to vary the fibre volume fraction. however, I leave it blank for the diameter fibre and areal density column. When I ran the simulation, I don't get any differences even there are varies of fibre volume fraction obtained. Is that because of the blanks that I left in yarn properties??

Yanie

[louisepb]

Hi Yanie,

If you look in the .eld file you will see exactly what the volume fraction values are and whether or not they have changed from one model to another. As I said in the other thread the .inp file with the voxel mesh output doesn't read in the .eld file so you need to add this if you want to use the volume fraction data.

Louise