Fracture surface formation of notched 2017A-T4 aluminium alloy under bending fatigue

Abstract

The effect of cyclic loading on facture surface topology in notched components made by aluminium alloys is not completely clear. Fractography and fracture mechanics can help to understand this interdependency. This paper aims to study the distribution of the fracture surface roughness of notched 2017A-T4 aluminium alloy after bending fatigue using an optical focus-variation surface measurement technique by applying the fracture zone concept. The effects of stress level at the notch root and the load ratio on fatigue crack growth and fracture surfaces are analysed. Profile and areal surface parameters of four fracture surface regions were investigated at incremental crack lengths of the specimens. Studies have confirmed that the surface areas associated with the main stages of fatigue phenomenon (i.e. crack initiation, crack propagation, and final rupture) have significant differences in roughness which can be explained by the different loading scenarios. Overall, fatigue fracture surfaces have smallest roughness values at the crack initiation stage and a gradual increase during the fatigue crack growth stage.

Fracture Surface Behavior of 34CrNiMo6 High-Strength Steel Bars with Blind Holes under Bending-Torsion Fatigue

“…In order to better understand the effect of B/T ratio on fracture surface parameters, a detailed analysis based on the Sa and Vv parameters was performed. These parameters turned out to be the most fitted, which was also confirmed in the papers [ 41 , 43 ]. Moreover, for the Df parameters, the one determined using the EBM in real units with fine resolution was selected as the most accurate.…”

“…This methodology, connecting the applied nominal loading with the fracture mechanics based on topographic parameters, provides important clues to improve the materials performance as well as to mitigate the fatigue damage mechanisms [ 32 , 41 , 42 , 43 , 46 ]. It can be used, for instance, in the field of forensic engineering to trace back to the origin of structural failures and correlate them with the applied loads, establishing the dependence between the loading scenario and the characteristic features of their surfaces.…”

“…More specifically, the paper aims to investigate the effect of the bending moment to torsion moment ratio on fatigue crack initiation of round bars with transversal blind holes; and on fracture surface topography. It is also focused on the identification and optimization of surface topography parameters in the context of fatigue crack mechanisms, where fracture topography is evaluated via the entire fracture area method [ 41 , 42 , 43 ].…”

Design Methodology and Application of Surface Texture: A Review

“…However, depending on the application area and region, some of these parameters are considered vital to surface functionality. A limited number of parameters is recommended to avoid the "parameter rash" [1,2]. Based on the effect of the surface morphology on the behavior of surfaces, surface texturing, which is a method that creates micro-pits, such as dimples [3] and grooves [4], on the mating surface under dry and lubricated conditions [5], was developed to lower friction and wear.…”

Fracture Areas Quantitative Investigating of Bending-Torsion Fatigued Low-Alloy High-Strength Steel

“…One of the most important outcomes is the introduction of field parameters S-and V-in the context of the description of fatigue fracture surfaces of 6082 aluminum alloy [24], fractal dimension for bending-torsion fatigue fracture surfaces [25,26], strain sequence consequences on fracture surface topographies in 7075-T651 aluminum alloy specimens [27], or also to compare profile and areal surface parameters for fracture specifications [28]. R-profile and areal S-parameters were also taken into account in another cited work by the Author [29], to explain the effect of various fatigue variables during fracture surface formation of notched 2017A-T4 aluminum alloy under bending fatigue. However, it was decided that the entire fracture surface method was compared to other areas of the fatigue fractures after bending, torsion and a combination of these loadings.…”