I conducted tensile and flexural tests for 4 different anisotropic materials (Fibre reinforced plastic). I got tensile strength of material C higher than material N. Whereas, higher flexural strength for material N than material C. Are my results correct? And if this can happen then what may be the possible reasons?
Please explain in detail.
Hi,
Having a high tensile strength and a lower flexural strength is possible. Due to Different consideration that should be made for tension and compression , a material will not have the same strength both in tension and compression. It should be notice that differences are due to effective cross section increases in compression and decreases in tension. The mechanical properties are dependant on chemical bonding and microstructure.
Yes, this is possible. actually depend on type of bonding in the molecules (crystalline or amorphous ) and also depend on orientation of fibers.
Hi,
Having a high tensile strength and a lower flexural strength is possible. Due to Different consideration that should be made for tension and compression , a material will not have the same strength both in tension and compression. It should be notice that differences are due to effective cross section increases in compression and decreases in tension. The mechanical properties are dependant on chemical bonding and microstructure.
Sorry, but fibre reinforsed materials are not isotr. Clarify, please, the materials type
In laminated FRPs, The stress at the outer fibres in flexure is higher than the stress that is present uniformly in tension. The probability of finding a stress level higher at the surface is more than the equal stress that is present over the cross section in tension. So for equal probabilities of failure, which is fact, the flexural strength of laminated frp like glass/epoxy or carbon/epoxy will be higher than the tensile strength. This not true every where. Please read PK Mallick 's book on FRCs.
In the specific case of FRPs, it is very likely to see different behaviors depending on the stack of fibers. If your materials have different fiber types/orientation/weave on the surface, this will cause a large change in flexural strength.
Sorry I agree with Prof. Vladislav Demenko ... your materials are not isotropic ... The properties as well as the response of the materials reinforced with fibers depend on many parameters related to the fibers : volume fraction, dimensions, orientations, bonding with the matrix........ Please check all these and build your answer.
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