Experimental investigation on possible dependence of plastic zone size on specimen geometry

Abstract

In this investigation the extent of the plastic zone size ahead of a crack-tip in single edge notched tension (SENT), compact tension (CT) specimens has been examined experimentally by micro-hardness technique and by elastic-plastic finite element analyses at different applied load levels. The magnitudes of the plastic zone size (PZS), r p ahead of crack-tip in the investigated specimens have been compared using normalized J-integral (J/aσ y , where, a-crack length and σ y-yield stress of the material). The results show the dependence of PZS on specimen geometry due to varied in-plane crack-tip constraint. The results also demonstrate that the existing analytical models do not explain the experimental results of PZS satisfactorily.

Estimation of the Plastic Zone in Fatigue via Micro-Indentation

“…Such works employed around 20 measurement points to characterise the crack tip. Subsequent works focused on a number of issues both related to the material and the techniques, such as the effect of using a very low load, the effect of the microstructure [ 19 ], the effect of high temperatures on the plastic zone [ 23 ] or the influence of the specimen geometry on the plastic zone [ 24 ]. Nevertheless, their plastic zone characterisation was based on measuring the hardness along single directions.…”

Elastic-plastic fracture analysis of anisotropy effect on AA2050-T84 alloy at different temperatures: A Numerical Study

“…he numerical procedure for the determination of J-integral was validated through an experimental fracture toughness test performed according to ASTM E1820-20b. The current numerical elastic-plastic fracture analysis procedure was adopted and validated from the earlier work [14]. The experimental fracture toughness test resulted in JIC of 11.589 N/mm at room temperature.…”

“…The material's plastic part's behavior was modelled by taking twenty divisions after the yielding point of the stress-strain curves along with elastic input viz., Young's modulus (E) and Poisson's ratio (ʋ). The material property input into the Abaqus 6.14 for elastic-plastic fracture analysis is adopted as similar to the earlier work of Kudari T et al [14,19]. The crack driving parameters such as J-integral and Crack Mouth Opening Displacement (CMOD) were extracted directly from ABAQUS 6.14 post-processor [18].…”

“…Constraint is defined as the restriction to plastic deformation at the crack front [22]. Plasticity around the crack front is measured as plastic zone size and shape, which depend on the in-plane dimension (crack length) and out-ofplane dimension (specimen thickness) [14]. 3D crack front stress tri-axiality fields significantly affect the constraint measured by PZS [19,23].…”

“…The fracture toughness depends on specimen geometry, load, and type of specimen, which coined the term constraint. Constraint generated at the crack front is measured through well-defined constraint parameters under Linear Elastic Fracture Mechanics (LEFM) and Elastic-Plastic Fracture Mechanics (EPFM) [7,8,9,10,11,12,13,14]. These constraint parameters are defined concerning either the stress field or the displacement field around the crack front.…”