2016年2月23日星期二

Woven Fabrics V.S. Chopped Strand Mat

Woven Fabrics V.S. Chopped Strand Mat

What is WOVEN FABRICS? 
Woven fabrics are strong reinforcements because the fibers are bundled into yarns oriented in just two directions. The warp and fill yarns run at 0 and 90 degrees respectively. Thus, fabrics are anisotropic, or strong in only two directions. Fabrics need to be oriented so the fiber yarns run parallel to the expected loads. If extra strength is needed in a different direction, another ply must be added at an angle to the first. The most common angles are +/- 45 degrees. 

Styles Of Woven Fabrics 
There are many styles of woven fabric to choose from. The most common are the plain weave fabrics where the warp and fill threads cross alternately. Plain woven fabrics are generally the lease pliable, but are easy to cut and handle because they don’t unravel badly. However, their strength is compromised due to the severe “prebuckling” already present in the fabric. As stated under tows, fibers only produce their greatest strength when they are perfectly straight. The frequent over/under crossing of the threads reduces the strength of plain weave types, though they are still adequate for all but the highest performance applications. 

What is FIBERGLASS CHOPPED STRAND MAT
The fibers are typically 3-4 inches in length and are randomly oriented.fiberglass chopped strand mat is not a very strong material because of the short fiber length. However, it is isotropic. This means that it is equally strong in all directions. Mat and fillers are the only composite reinforcements exhibiting this trait. This is the cheapest reinforcement form and is thus the most widely used. It is suitable for molds and part production. The random orientation effectively hides fabric print through of gelcoats and makes molds which are equally stiff in all directions. It should be noted that chopped strand mat is only compatible with polyester resin. 

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