The ASTM 3039 suggested a preparation of composite specimen for tensile test should be as per what i attached here....like it encourages 4methods based on fiber orientation.
For 0 degeree fiber orientation; the L=250mm, W=15mm, t=1mm and tab/gripping length =56mm by 1.5mm thickness.
For 90 degeree fiber orientation; the L=175mm, W=25mm, t=2mm and tab/gripping length =25mm by 1.5mm thickness.
For uniform and symetric degeree of fiber orientation ; the L=250mm, W=25mm, t=2.5mm and tab/gripping -emery cloth
For Random and discontinues degeree of fiber orientation ; the L=250mm, W=25mm, t=2.5mm and tab/gripping- emery cloth
Hi,
"Why ASTM 3039 standards for specimen geometry focus on the fiber orientation and why not on the materials type,composition and manufacturing method?"
The standard just describe the measurment conditions, and which factor in the measurement influences the tensile strength.
If you want ot compare different composites, you normally use one type of fibers, and the same methode or preparation.
Depending on the fiber direction and the production of the used fiber/fabric the composite strength changes. If you use just fibers in one directions the compostite strength is increased in this directions.
Was that what you want to know?
ya Thanks a lot for reaction,,
and, still have question on why only fiber direction used for that standared, because the mfg method can infulence more than the assumed direction. prepaing sample by handlay-up,injection molding and or RTM/resin transfer bag molding/ .....filament...has their contribution....so my interest is why not joint method like fiber orientation+mfg method as standard for ASTM3039....If not it is encourgeable to research out the effect on the strength by by considering fiber orientation alone and both (mfg +Fo)
The question is the tensile strenght, and how it could be reproducebly measured, on the same samples by others, who want to dertmine the tensile strength.
That is the task of a standard.
The production methode does not play a role if you have a final product, this is only the question in the devolpment phase.
Dear Yohannes Regassa,
ASTM 3039 is covering in-plane tensile properties for continuous and discontinuous fiber reinforced polymer matrix composites. Actually, the standart limits material type and reinforcement type. On the other hand, manufacturing method for fiber reinforced polymer are not so many: hand-lay up, VARIM, RTM, filament winding etc. and I think the standart leaves you free about this point (you are expected to give which method you used with the tests results). Still, the standart gives some explanation on the "Precision and Bias" section about the material factors.
Cheers,
Cemal
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