Gears are one of the most critical elements in mechanical power transmission systems. Today's competitive global market has brought increasing awareness to optimize the gear design. The gears are generally used to transmit power or torque and the efficiency of transmission is very high when compared to other kind of transmissions. The helical gear offers high contact and more friction which avoids slippage when compared to spur gear. Current trends in engineering globalization require results to revisit various normalized standards to determine their common fundamentals and those approaches needed to identify best practices, cost containment related to adjustments between manufacturers for missing part interchangeability and performance due to incompatibility of different standards. The work is to focus on investigating the combined eff ect of gear ratio, helix angle, face width and normal module on bending and compressive stress of high speed helical gear.
Light weight concrete has become more popular in recent years owing to the tremendous advantages it offers over the conventional concrete. Even Light concrete but at the same time strong enough to be used for the structural purpose. Lightweight concrete has been successfully used since the ancient Roman times and it has gained its popularity due to its lower density and superior thermal insulation properties. Compared with Normal weight concrete, Lightweight concrete can significantly reduce the dead load of structural elements, which makes it especially attractive in multi-storey buildings. The most important characteristic of light weight concrete beside its light weight is its low thermal conductivity. This property improves with decreasing density. The adaptation of certain class of light weight concretes gives an outlet for industrial wastes and dismantled wastes which would otherwise create problems for disposal. The conventional mix has been designed for M25 grade concrete. Coarse aggregate replaced with Pumice aggregate in volume percentages of 25% and 33.33% further Cement replaced with the Fly ash in weight percentages of 15%, 20%, 25%, 30% for study in the present investigation. The properties like Compressive strength, Split tensile strength, Flexural strength and Youngs' modulus of above combinations were studied and compared with conventional design mix concrete. It is observed that there is retardation in Compressive strength, Split tensile strength, Flexural strength and Young's' modulus for the light weight aggregate replaced concrete when compared to the concrete made with normal aggregate. For these light weight aggregate concrete mixes when 'cement' was replaced by 'fly ash' it is noticed that there is a marginal improvement in the properties studied. For 25% replaced light weight aggregate when cement was replaced by 15%, 20%,25% and 30%fly ash, the maximum gain in compressive strength of 18.71% at 28 days is observed for 20% replacement of fly ash. Similarly the gain in split tensile strength, flexural strength and Youngs' modulus of 16.66%, 29.51% and 10.15% is observed at 20% replacement of fly ash respectively. For 33.33% replaced light weight aggregate when cement was replaced by 15%,20%,25% and 30% fly ash, the maximum gain in compressive strength of 26.3 % is observed for 20% replacement of fly ash. Similarly the gain in split tensile strength, flexural tensile strength and Youngs' modulus of 19.23%,26% and 3.33% is observed at 20% replacement of fly ash respectively Hence we can infer that 20% replacement of cement by fly ash is optimum proportion among the proportions tested for the properties studied in the present investigation.
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