Effect of Stress Triaxiality on Plastic Damage Evolution and Failure Mode for 316L Notched Specimen

Abstract

To reveal the effect of stress triaxiality on plastic damage evolution and failure mode, 316L notched specimens with different notch sizes are systematically investigated by digital image correlation (DIC) observation, plastic damage analysis by finite element simulation, and void mesoscopic observation. It was found that the plastic damage evolution and failure mode are closely related with notch radius and stress triaxiality. The greater the stress triaxiality at the root is, the greater the damage value at the root is and the earlier the fracture occurs. Moreover, void distribution by mesoscopic observation agrees well with damage distribution observed by finite element simulation with the Gurson-Tvergaard-Needleman (GTN) damage model. It is worth noting that, with the increase in stress triaxiality, the failure mode of notched specimen changes from ductility fracture with void coalescence at the center position to crack initiation at the notch root, from both mesoscopic observation and damage simulation.

Influence of Sheet Conditions on In-Plane Strain Evolution via Ex-Situ Tensile Deformation of Ti-3Al-2.5V at Room Temperature

“…At global strain of 1.7%, a high volume fraction of micropores with spherical morphology (size~1-3µm), Figure 11b, were observed in the mid-section of the notched tensile sample due to the high stress triaxiality [23] of the region. These micropores were observed mostly in the softer β phase matrix.…”

“…J.S Kwame et alJournal of Materials and Applications 2021;10(1):[15][16][17][18][19][20][21][22][23][24][25][26] …”

Boundary condition effect on the evaluation of stress triaxiality fields

“…The stress fields may be used to evaluate stress triaxiality fields (written as the ratio between hydrostatic and von Mises equivalent stresses). Stress triaxiality plays an important role in damage and 2 fracture mechanics for predicting the type of failure (i.e., ductile or brittle [15,16,17,18,19]). Combinations of DIC and X-ray diffraction (XRD) techniques may be used to measure both total and elastic strain fields [20,21,22,23,23].…”

Localization of Plastic Deformation in Ti-6Al-4V Alloy

“…Tensile tests with notched geometries are utilized to investigate the influence of the constraint factor on the mechanical behavior of metals and alloys. The obtained data are used to calibrate constitutive models such as Johnson-Cook, Gurson-Tvergaard-Needleman, GISSMO, and other pressure-dependent damage models [11][12][13][14][15]. As the assumption of uniform strain in the gauge section is not valid in these tests, often, model parameters cannot be determined in a straightforward manner.…”