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Behavior of PVA fiber concrete under freezing and thawing cycles

2015-12-01T00:00:00Z

Title: Behavior of PVA fiber concrete under freezing and thawing cycles Authors: Xu, Fei; Xie, Xian-Song; Chen, Ju; Jin, Wei-Liang Abstract: In this study, the effect of polyvinyl alcohol (PVA) fiber on the behavior of concrete under freeze-thaw condition is investigated. Experimental investigations are conduct to measure the workability, compressive strength, bending strength, total charge passed and frost resistance of PVA fiber concrete in fresh water and NaCl solution under freezing and thawing cycles. The relative dynamic modulus of elasticity and the relative mass change of specimens at each cycle are measured. In addition, the surface deterioration of concrete specimens is also observed. Specimens with different volume content of fiber are tested in order to find the optimization PVA fiber content for frost resistance. Six series of specimens with PVA fiber volume content of 0%, 0.1%, 0.25%, 0.5%, 0.75% and 1.0% are tested. Finally, a model considering internal crack healing and cracking property of fiber concrete is proposed in this study. It is shown that the proposed model is able to predict the test results with reasonable accuracy. Page(s): 693-700

Plastic deformation analysis of wear on insert component and die service life in hot forging process

2015-12-01T00:00:00Z

Title: Plastic deformation analysis of wear on insert component and die service life in hot forging process Authors: Rajiev, R; Sadagopan, P Abstract: One of the main critical problems in the hot forging process is the temperature rise in the die cavity and huge stresses generated during forging operation which leads to die failure due to wear, deformation of die, cracks etc. In this study, wear analysis is carried out in a die in local industry. The simulation of the forging process on the die and the work-piece is carried out by using commercially available software (DEFORM). The flow of the material in the die, die filling, contact pressure distribution, sliding velocities and temperature distribution of the die have been investigated. The depth of wear on the die surface is evaluated using the finite element simulation and then the total wear depth was determined. By comparing the numerical results with the measurement taken from the worn die, the wear coefficient is evaluated at different locations of the die surface and finally an average value of wear coefficient is suggested. Page(s): 686-692

Optimization of machining parameters for turning AISI 4340 steel using Taguchi based grey relational analysis

2015-12-01T00:00:00Z

Title: Optimization of machining parameters for turning AISI 4340 steel using Taguchi based grey relational analysis Authors: Gupta, Munish K; Sood, P K Abstract: In metal cutting, the choice of cooling method influences the deformation mechanism, which is related to the cutting forces, tool wear and surface finish of the parts. The deformation mechanism of AISI 4340 steels machining conditions is known to be very different from that of commonly used industrial materials. Therefore, the effect of cutting parameters and cooling methods on cutting forces, tool wear and surface roughness in machining of AISI 4340 steel is of particular interest. This paper investigates experimentally and analytically the influence of various process parameters, given as cutting speed (v), feed rate (f) and different cooling conditions (i.e. dry, wet and cryogenic in which liquid nitrogen used as a coolant) using uncoated tungsten carbide insert tool on three major characteristics (cutting force, tool wear and surface roughness) of a turned AISI 4340 steel part. The Taguchi’s L9 orthogonal array, analysis of variance (ANOVA) and grey relational analysis (GRA) are executed to study the effects, significance, percentage contribution and optimum settings of given process parameters. The results obtained show that the machining performance can be improved by this approach. Page(s): 679-685

Experimental investigation of cenosphere particulate filled E-glass fiber reinforced vinylester composites under dry and water lubricated sliding conditions

2015-12-01T00:00:00Z

Title: Experimental investigation of cenosphere particulate filled E-glass fiber reinforced vinylester composites under dry and water lubricated sliding conditions Authors: Thakur, Sunil; Chauhan, S R Abstract: The aim of this work is to study the effect of cenosphere particulate on the tribological characteristics of glass fiber reinforced vinylester composites under dry and water lubricated sliding conditions. A synergistic effect is found for the combination of fiber and filler which lead to the improved tribological properties under dry and water lubricated sliding conditions. Effects of applied normal loads, sliding speeds and particle content on the tribological behaviour are also discussed. The experimental results show that the coefficient of friction and specific wear rate decrease with the increase in applied normal load and sliding speed. The experimental results also show that the composites exhibit lower coefficient of friction and lower wear resistance under water lubrication condition than under dry sliding. To validate the experimental data the morphologies of the worn surfaces are carried by means of scanning electron microscope (SEM). Page(s): 669-678