Browsing by Author "Rao, R.M.V.G.K."

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Diffusion of water in epoxy composites with different sequential arrangements of woven roving (WR) and chopped strand mat (CSM) reinforcements was studied on immersion in water at 298 K and 323 K. Laminates with CSM as skin layers showed higher diffusivity and equilibrium moisture content than WR as skin layers. The diffusion parameters obtained from the experiment conducted up to saturation limits of 323 K showed good correlation with the data computed using a moisture absorption programme written on lines suggested by G.S. Springer. Hence data at lower temperatures are also generated by using the above programme, thus shortening the time to reach saturation levels.
(Hygrothermal effects on chopped fibre/woven fabric reinforced epoxy composites. Part A. Moisture absorption characteristics) Singh, K.Shanker; Singh, P.N.; Rao, R.M.V.G.K.
1991
Hygrothermal effects on chopped fibre/woven fabric reinforced epoxy composites. Part A. Moisture absorption characteristics
(1991) Singh, K.Shanker; Singh, P.N.; Rao, R.M.V.G.K.
Diffusion of water in epoxy composites with different sequential arrangements of woven roving (WR) and chopped strand mat (CSM) reinforcements was studied on immersion in water at 298 K and 323 K. Laminates with CSM as skin layers showed higher diffusivity and equilibrium moisture content than WR as skin layers. The diffusion parameters obtained from the experiment conducted up to saturation limits of 323 K showed good correlation with the data computed using a moisture absorption programme written on lines suggested by G.S. Springer. Hence data at lower temperatures are also generated by using the above programme, thus shortening the time to reach saturation levels.
Hygrothermal effects on chopped fibre/woven fabric reinforced epoxy composites. Part B. Degradation studies
(1991) Singh, K.Shanker; Singh, P.N.; Rao, R.M.V.G.K.
Studies were conducted on the degradation of short beam shear (SBS) and impact strength (Izod) properties of glass epoxy composite specimens with sequential arrangements of woven roving (WR) and chopped strand mat (CSM) reinforcements, (Figure 1 of Part A) immersed in water at two different temperatures (298 K, 323 K). It was found that composites with higher fibre content, though possesed of a higher initial shear strength, degraded faster than those with low fibre content. This was attributed to a thin resin layer separating the glass layers and a consequential increased surface area around the fibres for the moisture absorption. Further, it was noted that while the impact strength too degraded with exposure period, the degradation patterns are almost identical in all types of laminates within the limits of fibre resin ratio chosen.
Studies were conducted on the degradation of short beam shear (SBS) and impact strength (Izod) properties of glass epoxy composite specimens with sequential arrangements of woven roving (WR) and chopped strand mat (CSM) reinforcements, (Figure 1 of Part A) immersed in water at two different temperatures (298 K, 323 K). It was found that composites with higher fibre content, though possesed of a higher initial shear strength, degraded faster than those with low fibre content. This was attributed to a thin resin layer separating the glass layers and a consequential increased surface area around the fibres for the moisture absorption. Further, it was noted that while the impact strength too degraded with exposure period, the degradation patterns are almost identical in all types of laminates within the limits of fibre resin ratio chosen.
(Hygrothermal effects on chopped fibre/woven fabric reinforced epoxy composites. Part B. Degradation studies) Singh, K.Shanker; Singh, P.N.; Rao, R.M.V.G.K.
1991
The effects of sulphuric acid concentration and the sequential layup of glass fibre reinforcements on the diffusion behaviour of glass epoxy composite laminates were studied. In all, composites of six different resin systems viz., general purpose polyester, bis phenol-A polyester, vinyl ester, LY 556 epoxy, and MY 750 epoxy resins, reinforced with different layup sequencing consisting of chopped strand mat (CSM) and woven roving mat (WR) were exposed to sulphuric acid environments of different concentrations. The results of the study indicated that isophthalic polyester resin exhibited maximum resistance to sulphuric acid while general purpose polyester resin performed relatively inferior. The diffusion phenomenon became anamalous as the concentration of the sulphuric acid increased. Among the layup sequences considered, composite specimens with CSM as the skin layers exhibited higher weight gain than those with WR as the skin layers.
(SAGE Publications Ltd, Acid resistance of glass fibre composites with different layup sequencing: Part I-diffusion studies) Pai, R.; Kamath, M.S.; Rao, R.M.V.G.K.
1997