analysing a 3d composite vessel

huangyhg

analysing a 3d composite vessel
i am analysing a 3d composite(carbon/epoxy) pressure vessel with ansys using shell99 elements and i want to obtain tsai-wu failure criterian.i have only these properties1,2 or x,y are in plane 3 or z is out of plane)
modulus: e1,e2,g12
strenght: xt,xc,yt,yc,s
poison ratio:nu12
but there are more properties required by ansys,if i leave other blank ansys shows an error,until i use a value for modulus e3,and strenghts zt,zc,now ansys will solve the problem.i think this is because the tsai-wu failure criteria used in ansys are 3-d versions of the failure criterion.plus these there are other properties which leaving them blank does not make an error in ansys but this may influnce on the results.these properties are:
g23,g13,nu23,nu13,zt,zc,syz,sxz.now what should i do
cheers
alleak
check out our whitepaper library.
why the 3d analysis?  you should be able to reduce this to a plane stress application and use the failure criteria directly.  
numerous texts on composite mechanics have typical examples.  check out gibson, jones, tai, or whitney.
regards,
qshake
eng-tips forums:real solutions for real problems really quick.