Determine the Tensile Modulus and Shear Modulus of Woven Roving

[fglass]

Question: If the fiber weight per unit area of a woven roving(WR) is given as 24oz/sq yard fabric with a 5 X 4 weave style, is it a wise idea to calculate the Young's Modulus (Tensile Modulus) of the WR by assuming different volume fractions (Vf=0.3,0.4,0.5,0.6 etc)?
From what I understand,

Vf=W/(t*d)
where, W=weight per unit area (known value)
t=thickness (known value)
d=fiber density (known value)

I saw this equation from a book. Is this equation make any sense to everybody? Besides that, I wonder if anybody know the way to calculate Young's Modulus, or Shear Modulus, of WR, Chopped Strand Mat, Continuous Filament Mat and Roving if testing is unapproachable at this point?

Your help is much appreciated.

 

[patprimmer]

Woven rovings are normally used as part of a composite structure.

It is difficult to estimate the properties of the composite by analysing just the properties of component parts when tested individually.

Factors like twist, load sharing between filaments, cripple or deviation from straight line, resin matrix mechanical properties and adhesion to reinforcement and fibre to resin ratio all play a part in final composite properties.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Blackhorse007]

F-glass, if the supplier cannot provide i think it might also be quite hard for us as there are some properties that you would need to aquire from them. Probably they are too sensitive, try asking, if it is not sensitive to obtain the information and the supplier really do not know, try contacting the mfger with the help of ur supplier?

 

[fglass]

Blackhorse007 - I did contact the supplier but no result from them. Basically, my boss wanted me to build a material library for future composite (laminate) analysis. To cut the cost of testing, he wants me to predict those material properties based on the formulas by looking at some journal paper / books. I wonder if anybody knows any sites that provides the properties of Chopped Filament Mat, Chopped Strand Mat, Roving, and Woven Roving? I have tried Matweb, but no result.

 

[patprimmer]

Such material is available from some suppliers of resins, reinforcement or prepregs.

It is also available from your local supplier, find a supplier who publishes such data.

I have also seen it in several how to design with FRP books.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Blackhorse007]

I think u would have to go direct to the manufacturers they would have what u require.

These materials are no easy to calculate off hand, coz some of the components are trade secret.

 

[fglass]

As I said, I couldn't get any properties from the supplier. They did provide brochures but the information is very limited. They gave the properties in laminate form and I am not sure what materials they have in the laminate. Aarrrgghhh, this is driving me nuts. My boss approached me few hours back and I had turned in my guess to him. Hopefully, I will not get fired after working for only 2 months.

 

[patprimmer]

The only useful information is in laminate form for reasons already stated.

Have you tried Owens Corning, Akzo Nobel and DuPont for data on reinforcements and resin and prepreg manufacturers for resin data.

Books on FRP boat construction will have some data.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Demon3]

I can give you a tip. The strength and modulus are both dominated by the fibres not the matrix because the fibre has much higher modulus and strength than the fiber. Therefore as a first approximation take the data your supplier gave you and assume that's valid (with some margin left for error) for the same fibers in all polymers at the same fiber amount. For impact you cannot assume that as it varies a lot between different fiber-filled polymers.

 

[Blackhorse007]

hi do not be stressed, i am sure if u ask the supplier nicely, he would be able to dig out some information from the manufacturers.

The guys who manufacture the product must know what they are manufacturing and must know all the figures that u require. so be nice to them, they might let u in on these secrets.

 

[patprimmer]

Even though almost all the strength is contained in the fibres, their direction of lay, and interactions between fibres re load sharing is influenced to some extent by the matrix. Also strength to weight is heavily influenced by the resin.

Major fibre manufacturers do publish some data and have it in the public domain. It is not secret. It is often in the form of tests on an individual fibre. There is a change in properties when tested as a yarn as you never get 100% perfect load sharing. One fibre will always start to bear load a bit before some others, so the first fibre to bear load will be stressed more at a given yarn strain

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.