Development of Carbon Fibre Metal Laminates (CFML): Design, Fabrication and Characterisation

Abstract Fibre Metal Laminates (FMLs) are hybrid materials consisting of metal layers bonded to fibre-reinforced polymer layers. CFML is an FML developed at NAL consisting of thin aluminum foil combined with carbon-epoxy and glass-epoxy prepreg materials. CFML is proposed as the candidate material for the leading edges of wing and empennage of an aircraft as it has superior characteristics in terms of shape retention (due to highly linearly elastic material like carbon/epoxy), energy absorption capability (due to layered structure and plastic deformation), lightning protection (due to the presence of aluminum layers), and also due to its cost effectiveness (lightweight construction and simple production techniques). An important design issue is the internal residual stresses built into the laminate during curing due to differential coefficients of thermal expansion of the different material systems. This report discusses the methods and issues involved in the fabrication of CFML. CFML laminates were fabricated and Tensile, Compression, ILSS and Flexure testing of standard specimens for different lay-ups were done. The failure modes exhibited during these tests indicate that these materials could be better in energy absorption. However, these conclusions need to be validated with the experiments to quantify their energy absorption capability

Assay of sulfur compounds with 1-​chlorobenzotriazole

A simple but accurate potentiometric method for the estn. of certain sulfur contg. org. compds. has been developed, based on their oxidn. with 1-​chlorobenzotriazole. A back-​titrn. procedure can also be used. The nature of oxidn. in different media is discussed and the oxidn. products have been identified

Performance of Distributed CFAR Tests in Nonhomogeneous Background

We evaluate the performances of several distributed CFAR tests operating in nonhomogeneous background conditions. The analysis considers the detection of Rayleigh target in Rayleigh clutter sith the possibility of differing clutter power levels in the test cells of distributed radars. The tests considered include the previously defined maximum order statistic detector (MOS), belonging to a class of signal-plus- order statistic (S+OS) detectors, a new normalized test statistic (NTS), also belonging to the S+OS class, the OR and the AND fusion rules. Numerical results studied for a two radar system show how the false alarm rate of the MOS test changes with differences in the clutter power levels of the test cells. Results also indicate that, with differing test cells\u27 power levels, the OR fusion rule can be quite competitive to more complex tests, viz. NTS and MOS

Diversity Combining in Antenna Array Base Station Receiver for DS/CDMA System

This paper analyses few schemes for combining base station antenna array signals in wireless DS/CDMA. The performances of equal gain combining (EGC), likelihood rank test (LRT) and a modified rank test (MRT) are evaluated using simulation studies. The results indicate that, under certain assumptions on multiple access interference statistics, the probability of error of MRT is lower than that of EGC, if a few high power interfering users are present along with a low power user of interest. If there are a moderately large number of users and if the received power of all the users are nearly the same, then EGC outperforms MRT. In fact, under this condition, the performance of EGC is close to that of the optimal likelihood ratio test

Investigation of electrochemical behavior of plasma nitrided Ti-6Al-7Nb alloy in Hanks’ Solution

Titanium alloy Ti-6Al-7Nb was plasma nitrided using inductively coupled RF Plasma with 100% Nitrogen at 750, 800 and 850°C for 4 h. Micro Raman studies show the formation of titanium nitrides. Potentiodynamic polarization studies in Hanks’ solution show the corrosion resistance of the untreated samples to be better than the treated samples. Electrochemical Impedance Spectroscopy (EIS) studies show higher charge transfer resistance and lower double layer capacitance for the substrate compared to the nitrided samples. FESEM images of samples immersed in SBF show that growth of apatite is more and the size of deposits are larger on nitrided samples as compared to that on the untreated substrate. Nitrided samples immersed in Hanks’ solution for 7 days show higher amount of calcium, phosphorous and oxygen than the substrate

Development of CGLARE: Design, Fabrication and Characterisation

Fibre Metal Laminates (FMLs) are hybrid materials consisting of metal layers bonded to fibre-reinforced polymer layers. CGLARE is an FML developed at NAL consisting of thin aluminum foil combined with carbon-epoxy and glass-epoxy prepreg materials. CGLARE is proposed as the candidate material for the leading edges of wing and empennage of an aircraft as it has superior characteristics in terms of shape retention (due to highly linearly elastic material like carbon/epoxy), energy absorption capability (due to layered structure and plastic deformation), lightning protection (due to the presence of aluminum layers), and also due to its cost effectiveness (lightweight construction and simple production techniques). This paper describes the issues regarding the development of CGLARE such as surface preparation of aluminum foils and bonding of aluminum with glass. Tensile, Compression, ILSS and Flexure testing of ASTM standard CGLARE specimens for different layups have been done. An important design issue is the internal residual stresses built into the laminate during curing due to differential coefficients of thermal expansion of the different material systems. The paper presents these results that indicate some properties of these material systems that could be exploited for energy absorption in the leading edges of the aircraft

Influence of Pongamia, Mahua and Neem cakes on finger millet productivity and soil fertility

A field experiment conducted at Bio-fuel park, Agricultural Research Station, Madenur, Hassan in Kharif season of 2009 to asses the performance of finger millet (Eleusine coracana L.) under different organic manure treatment consisting of four treatments viz., recommended FYM and NPK through inorganic fertilizers as control, Pongamia, Mahua and Neem cake with 5 replications laid in randomized complete block design. The results revealed that application of recommended FYM along with neem cake equivalent to 100% recommended N performedbetter in respect of finger millet productivity and maintenance of soil fertility followed by recommended FYM with 100% NPK through fertilizers. Nutrient supplementation with different oilcakes proved superior in respect of soil sustainability

Manurial value of byproducts of bio-diesel feed stocks on finger millet grain and dry fodder productivity

A replicated field experiment was conducted at Agricultural Research Station (ARS), Madenur located in Hassan District, Karnataka in rainy season during 2007 to assess the manurial value of by-products of bio-diesel feed stocks-pongamia and neem oil seed cakes vis-à-vis conventional plant nutrients sources (combination of farm yard manure and inorganic fertilizers) on the grain and fodder productivity of finger millet, the staple food cereal of southern Karnataka. Grain and dry fodder productivity of finger millet crop grown using pongamia and neem seedoil cakes is comparable to that grown using conventional plant nutrient sources. Application of plant nutrients only through pongamia and neem seed oil cakes resulted in higher available soil Nitrogen, Potassium and Organic Carbon contents

Manurial value of byproducts of bio-diesel feed stocks on finger millet grain and dry fodder productivity

A replicated field experiment was conducted at Agricultural Research Station (ARS), Madenur located in Hassan District, Karnataka in rainy season during 2007 to assess the manurial value of by-products of bio-diesel feed stocks-pongamia and neem oil seed cakes vis-à-vis conventional plant nutrients sources (combination of farm yard manure and inorganic fertilizers) on the grain and fodder productivity of finger millet, the staple food cereal of southern Karnataka. Grain and dry fodder productivity of finger millet crop grown using pongamia and neem seedoil cakes is comparable to that grown using conventional plant nutrient sources. Application of plant nutrients only through pongamia and neem seed oil cakes resulted in higher available soil Nitrogen, Potassium and Organic Carbon contents