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RE: Composits- Help

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Hi Prasad,

I am not in expert in the composite structures.  But I have some experience in designing Tensioned Fabric Structures.

When modeling the fabric with two layers of fibres keep in mind that your fibres in the perpendicular directions have different properties.  The warp (straight) fibres are stiffer than the fill ones (woven).  The fill fibres have to straighten out first before they can pick up any load.  So trick is to set the correct modulus of elasticity which usually is tested for.  As far as the angle between fibres it is usually 90 degrees.

Hope this helps

Sasha Itsekson, P.E.

 ----------
From: 	M/S SATELLITE SYSTEMS[:satsys(--nospam--at)hd1.vsnl.net.in]
Sent: 	Thursday, January 22, 1998 1:30 PM
To: 	seaoc
Cc: 	ITSEKSON SASHA
Subject: 	Composits- Help


Hello Everybody !

  Can anybody throw some light on the following problem faced by us ?

     MODELING OF FRP COMPOSITE MATERIALS

     COMPOSITES MADE OF WOVEN ROVINGS(FABRIC) HAVE FIBRES IN TWO MUTUALLY
     PERPENDICULAR DIRECTIONS.  WHILE MODELLING FOR FEM ANALYSIS EACH LAYER
     IS ASSUMED TO HAVE FIBRES ORIENTED IN ONE DIRECTION ONLY.  THERE IS NO
     SEPARATION OF FIBRES IN A COMPOSITES MADE OF FABRIC. WHAT SHOULD BE THE
     FIBRE ANGLE WHILE MODELLING THE FABRIC ELEMENTS?  WHAT SHOULD BE THE
     PROPERTIES OF THE COMPOSITE MATERIAL IN SUCH A LAYER?

  If we use 0 or 45 or 90 deg. it represnets only one direction and
the results does not match with actual test results.

Thank you in anticipation

Prasad
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