Composite Materials Research Progress

Conclusion
An Experimental and Analytical Study of Unidirectional Carbon Fiber… 161
(a) (b)
Figure 28. Simulated micro damage patterns. (a) Weak interface, (b) Strong interface.
Using the solution impregnation and filament winding techniques, an innovative
manufacturing method was introduced to manufacture nano-phased carbon/epoxy prepreg
tapes/tows from a nanoparticle modified epoxy resin system.
It was seen from TGA that the as-prepared nanocomposites were thermally more stable
than their neat counterparts. An improvement of about 7 0 C was noticed. The improvement in
thermal stability was believed to have been caused by increased cross-linking and better
interactions between the epoxy and SiC nanoparticles.
As seen with DSC and DMA, an improvement in glass transition temperature (Tg) of the
nano-phased system was about 5 0 C. The improvement is due to the restricted mobility of the
chain segments in the presence of SiC nanoparticles, as a result of a greater number of crosslinked
polymer chains.
Response of nano SiC infused composites under flexure loading showed significant
improvements in strength as well as stiffness over the neat ones. On an average the increment
in strength and stiffness was 32% and 20% respectively over the neat systems. It is believed
that the higher strength of the SiC systems is attributed to better interfacial bonding and the
resistance offered by the nanoparticles to crack propagation.
In respect of tensile strength and stiffness, the nanocomposite systems offered
improvements between 7 and 10%. It was seen that all the test coupons (neat and nanophased)
failed in the gage length and failure modes were as described in the ASTM standard.
This nominal improvement in the tensile properties was believed to have occurred because in
tension, stresses in fibers were more dominant than in the nano-phased matrix and the
property improvement is merely due to the improved properties of the resin.
Monte Carlo simulation technique has been established to simulate unidirectional layered
neat and nano-phased composites. The simulation results are in agreement with the
experimental results. Tensile failure process was simulated and the damage zone and micro-