Nylon unidirectional glass fiber tapes.... 1

[gregf84]

Hello,
Does anyone have material properties for nylon resin unidirectional glass fiber tapes used in composite prepregs?

Greg........

 

[RPstress]

American Matrix Corp used to market this but their website seem to have vanished and Google doesn't seem helpful in finding them or their successors. Attached is the little bit of info that I downloaded in 2009. The ILSS ("Short Beam Shear") for the woven can be used with multidirectional UD and as a lower bound for all-0° UD and the temperatures should be the same for UD as for woven. Assuming same fiber volume fraction for UD as for woven. I afraid don't know how the woven Izod toughnesses might be changed with UD. I'd also be interested in the 2-direction properties for UD in such a tough thermoplastic; shame there's no info. Google seems quite cagey about telling me about UD glass-thermoplastic (a million sites for short fibers-TP of course). Let us know if you find a source for any info.

 

[RPstress]

I answered this before looking at your question on analysis of this material. The little bit of out-of-date Matrix Corp info looks especially inadequate in the light of thinking about explicit-FE impacts.

 

[gregf84]

Hello RPstress,
Thanks for the information provided. Yes, I would need to have more data for the LSDyna Mat 54 material card. But this is more then I currently have.

Greg.............

 

[gregf84]

Hello RPstress,
Is the data you provided for a woven composite thermoplastic? It is not for a unidirectional glass fiber with nylon tape, correct?

Greg..............

 

[RPstress]

LH column is woven and RH column is UD. I think matrix is dry Nylon 6. Nylon 66 or some other common Nylons might be a bit different but not much. Moisture might make quite a bit of difference, as might elevated temperature. Nylon (polyamide aka PA) is a bit of demon for soaking up H₂O and it softens it a fair bit. That and effects of temperature make it less desirable for structures hence its classification one of the 'engineering' thermoplastics as opposed to the expensive 'high performance' thermoplastics like PEEK, PPSU, etc. Autopeople seem to quite like glass/PA, though.

[A bit of justification for the woven/UD claim. There were two columns in the doc I attached: '0°/90° fiber orientation' and '0° fiber orientation'. Tensile Strength is given as '51' ksi and '126' ksi, and Tensile Modulus as '3.2' and '5.5' Msi. I think from that, that the '0° fiber orientation' column is for UD all at 0°.

Very roughly, for anticipated moduli, glass fiber E ~72 GPa so E for UD at 0° and 50% volume fraction E is about 72*0.5 = 36 GPa or 5.2 Msi. E for 0/90 woven = 72*0.5/2 * 1.1 = 20 GPa or 3 Msi. (NB: basic fiber strength can be from 70000 to 74000 MPa. And the 1.1 is a very rough bodge to allow for the 90° layers contributing something, which they do with glass.)

For strength of UD at 0° you have maybe 2000*0.5*0.8 = 800 MPa or 116 ksi, cf. 126. All highly questionable; the 2000 as a basic fiber strength could well be nearer 2400 and the 0.8 is just a guess because strength is knocked down more than modulus in the real world. Another guess at an upper boundary is 2400*0.5*0.85 = 1020 MPa or 148 ksi. I've seen 2800 MPa used for basic fiber strength and the value for a virgin (no damage) E-glass fiber is often quoted as 3450 MPa (500 ksi). Woven with 50% of the fibres at 90° should be very roughly 50% UD, and for strength it's a bit less than that here (51/126 = 40%). I don't know why, but the crimp in the weave may be affecting strength more than modulus.

For the woven you can go to the effort of using micromechanics to work out the E for the 90° fibres + resin then adding that to the E for the UD and dividing by 2 but there's not much point. Micromechanics is only really good for rough estimates. Suffice to say that the two AM Corp columns appear to be to woven and UD and are reasonably consistent with other polymer matrix values.]

I know of no way to estimate the toughness of composites from some dodgy micromechanics and I have no comparative data from which to make a guess at how the woven numbers may change. The AM Corp Izods probably won't help with modeling the material as it breaks. Izods (and Charpys) are mostly for use with comparisons. Charpys can be used with steels to estimate critical stress intensities (KIcs) but this is mainly by a process of curve fitting. The basic Nylon will have some strain energy release rate (GIc) data but how that is modified by being in a composite with glass layers is not really calculable as far as I know. If you got a body of data for glass with similar resins you could estimate it but I think that's unlikely to be available. You need a competent test house if you want to measure GIc data. In the UK MERL is well respected for this sort of thing. Not sure about the US.

As well as the above BS about the properties given, at the very least you also need some compression properties. Glass is often quite good in compression but I'm not sure about with a low modulus matrix like PA, especially after moisture has had a bite out of it. For some very rough first pass estimates you could come up with estimates of compression properties but I wouldn't trust them to be within ±50%.

Also I don't know what rules autopeople like for allowing for damage. Glass is often quite low for things like open hole tension.

 

[gregf84]

Hello RPstress,
Thank you for the detailed explaination and the insight. Your experienced input is much appreciated.

Greg.........

 

[Gunner]

Greg,
I sold American Matrix when I started Fibrtec:

http://www.fibrtec.com.

Strictly thermoplastic prepreg production, not parts making as American Matrix did. email me at Bob@fibrtec.com and I will send you a data sheet.

Bob Davies