Composite Analysis And Testing in Aviation

[yusf]

Hello All;I had asked same in composite platform but again i would like to kindly ask here too..

My question is especially in the field of testing of composite materials and making use of the datas obtained from those tests.If i test a 2.5 mm thick specimen and get result how can i use the faiure data obtained from test for my let's say 3 to 5 mm thick composite design.Sould i perform other specimen tests that are in 3 ,4 and 5 mm thick? in order to model all thickness region as single lamina in ABAQUS.?Should i perform analytical lamination theory to find each individual layer propertis by guessing until precise EXX EYY at which the whole laminate appearent modulus equals to the test value? AND THEN modelling other thick regions by calibrated EXX EYY?Any idea? thanks in advance...

 

[rb1957]

would you expect the same failure mode for each specimen ?

 

[yusf]

From the maksimum failure strain point of view i think yes.

Any idea about the analysis procedure?

 

[cpinz]

Hi all,

-The failure from simple tension/compression test on unnotched specimen usually represents the starting point to further investigation on the failure of laminate. Then you should decide, on the basis of applications, if such tests are enough and reprentative of the real behaviour of material.
What about allowables and knockdown factors ?
Max. failure strain is accepted in aeronautics, but you could be requested to adopt different failure criteria (I argue this from your sentence "From the maksimum failure strain point of view i think yes".)

- about FEM analysis: it would be crazy to test specimens every time that you increase the thickness of your laminate, unless you change materials !
Elastic moduli, poisson modulus, etc.. are derived form data statistically analyzed and only then used in FEM analysis, changing thickness "virtually".

Sometimes simple Classical Laminate Theory programs could be worth than a complete fem analysis