Experimental investigation of effect of specimen thickness on fracture toughness of Al-TiC composites

Abstract

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 involved 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.

Fracture Toughness Investigation of AL6082-T651 Alloy under Corrosive Environmental Conditions

“…When the specimen thickness gets close to the critical limit, the fracture toughness value seems stable. Plane-strain fracture toughness [38], denoted by KIc, is the name given to the estimated fracture toughness at this point. Equations (3 and 4) provide the conditions for the plane-strain fracture toughness [37]:…”

Fracture Behaviour of Aluminium Alloys under Coastal Environmental Conditions: A Review

“…Also, they utilised different specimen types, including CT, SENB, and circumferential notched tensile (CNT) specimens, and their findings indicate that all these specimen types produced consistent results. Researchers [8,12,[25][26][27][28] generally prefer CT specimens for fracture toughness testing due to their standardised nature, widespread acceptance, and the assurance of consistent and comparable outcomes. CT specimens are well-suited for Mode I crack propagation, which is common in engineering applications, and they create near-plane strain conditions, simplifying crack growth analysis.…”

“…Conditional load value PQ is determined by the secant line (OP5) with a slope (P/V)5 equal to 0.95 times the slope of the tangent OA between (PL) and (PU), denoted as (P/V)o. Researchers [8,12,[25][26][27][28] generally prefer CT specimens for fracture toughness testing due to their standardised nature, widespread acceptance, and the assurance of consistent and comparable outcomes. CT specimens are well-suited for Mode I crack propagation, which is common in engineering applications, and they create near-plane strain conditions, simplifying crack growth analysis.…”

Effect of specimen crack lengths on stress intensity factor for Al6061-TiC composites using experimental and 3D numerical methods

“…However, the evaluation of fracture toughness is essential for the reliable use of these composites for structural parts and components. The effects of specimen thickness on fracture toughness ( K IC ) for these Al6061-TiC composites were studied experimentally (Raviraj et al , 2016). Several methods have been developed in past, to compute the stress intensity factor ( K ) for engineering problems with complex geometry and loading (Murakami, 1987).…”

“…The experimental work so far has focussed on the effects of specimen thickness on fracture toughness for various Al6061-TiC composites in our earlier work (Raviraj et al , 2016). The predictability of effects of specimen crack lengths on fracture toughness for these Al6061-TiC composites using experimental and 3D elastic fracture finite element simulations have motivated the present study.…”