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Item Effect of TiC addition on fracture toughness of Al6061 alloy(American Institute of Physics Inc. subs@aip.org, 2018) Raviraj, M.S.; Sharanaprabhu, C.M.; Mohan Kumar, G.C.Al 6061 matrix was reinforced with different proportions of TiC particles such as 3wt%, 5wt% and 7wt% and the effect on fracture toughness was studied. Al-TiC metal matrix composites were produced by stir casting method to ensure uniform distribution of the TiC particulates in the Al matrix. LEFM (Linear Elastic Fracture Mechanics) has been used to characterize the fracture toughness using various specimen geometries. The compact tension (CT) specimens with straight through notch were machined as per ASTM E399 specifications. All the specimens were machined to have constant a/W=0.5 and B/W was varied from 0.2 to 0.7. A sharp crack initiation was done at the end of notch by fatigue loading using servo-hydraulic controlled testing machine. Load v/s crack mouth opening displacement (CMOD) data was plotted and stress intensity factor, KQ determined. Critical stress intensity factor KIC was obtained by plotting KQ v/s thickness of specimen data. The fracture toughness of the composites varied between 16-19 MPa√m as compared to 23MPa√m for base alloy Al6061. Composites with 3wt% and 7wt% TiC showed better fracture toughness than 5wt% TiC reinforced Al metal matrix composites. © 2018 Author(s).Item Experimental investigation of effect of specimen thickness on fracture toughness of Al-TiC composites(Gruppo Italiano Frattura, 2016) Raviraj, M.S.; Sharanaprabhu, C.M.; Mohan Kumar, G.C.In this paper, the macro and micro-mechanical fracture behavior was studied for aluminum (Al6061) alloy matrix, reinforced with various proportions of TiC particles such as 3wt%, 5wt% and 7wt%. The Al6061-TiC metal matrix composites were produced by stir casting method to ensure uniform distribution of the TiC particulates in the Al matrix. The compact tension (CT) specimens were machined according to ASTM E399 specifications to evaluate the fracture toughness for Al6061-TiC metal matrix composites. The CT specimens were machined for crack to width (a/W) ratio of 0.5 and thickness to width (B/W) ratios of 0.2 to 0.7 with an increment of 0.1. Load versus crack mouth opening displacement (CMOD) data was plotted to estimate stress intensity factor KQ for various thicknesses of the specimen. The fracture toughness KIC was obtained by plotting stress intensity factor versus thickness to width ratios of specimen data. The fracture toughness of these composites varied between 16.4-19.2 MPa?m. Scanning Electron Microscope (SEM) studies was made on the fractured surface of the specimens to understand the micro-mechanisms of failure involve in these composites. Void initiation is more significant in the matrix near the interface. The micro-cracks grow from these micro-voids and crack propagates by linking these micro cracks locating the crack path preferentially in the matrix adjacent to the interface indicating ductile fracture. © 2016, Gruppo Italiano Frattura. All rights reserved.Item Effect of specimen crack lengths on stress intensity factor for Al6061-TiC composites using experimental and 3D numerical methods(Emerald Group Publishing Ltd. Howard House Wagon Lane, Bingley BD16 1WA, 2017) Raviraj, M.S.; Sharanaprabhu, C.M.; Mohan Kumar, G.C.Purpose-The purpose of this paper is to present the determination of critical stress intensity factor (KC) both by experimental method and three-dimensional (3D) finite element simulations. Design/methodology/approach-CT specimens of different compositions of Al6061-TiC composites (3wt%, 5wt% and 7wt% TiC) with variable crack length to width (a/W0.3-0.6) ratios are machined from as-cast composite block. After fatigue pre-cracking the specimens to a required crack length, experimental load vs crack mouth opening displacement data are plotted to calculate the KC value. Elastic 3D finite element simulations have been conducted for CT specimens of various compositions and a/W ratios to compute KC. The experimental results indicate that the magnitude of KC depends on a/W ratios, and significantly decreases with increase in a/W ratios of the specimen. Findings-From 3D finite element simulation, the KC results at the centre of CT specimens for various Al6061-TiC composites and a/W ratios show satisfactory agreement with experimental results compared to the surface. Originality/value-The research work contained in this manuscript was conducted during 2015-2016. It is original work except where due reference is made. The authors confirm that the research in their work is original, and that all the data given in the article are real and authentic. If necessary, the paper can be recalled, and errors corrected. © Emerald Publishing Limited.Item Experimental and 3D FE evaluation of crack initiation energy J 1C in Al6061-TiC composites(IOS Press Nieuwe Hemweg 6B Amsterdam 1013 BG, 2018) Raviraj, M.S.; Sharanaprabhu, C.M.; Mohan Kumar, G.C.M.The test data crack initiation energy in Mode-I fracture, J 1C is determined experimentally for various compositions of Al6061-TiC composites by using compact tension (CT) specimen with variable aW ratios. Also, 3D nonlinear (elastic-plastic) finite element analysis was carried for Compact Tension (CT) specimen to evaluate J 1C, ahead at the crack-front of several Al6061-TiC composite specimens with various crack lengths. The 3D FEA J 1C results were compared with the experimental results. The J 1C values decrease with increasing crack length of the specimen because of decrease in load carrying capacity of the specimens. Al6061-TiC composites exhibit higher fracture toughness values than their counterparts Al-SiC composites. © 2018 IOS Press and the authors. All rights reserved.