SKM 2023 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 20: Topical Session: Fundamentals of Fracture – Microstructure Impact on Fracture (Experiments)

MM 20.2: Vortrag

Dienstag, 28. März 2023, 14:30–14:45, SCH A 216

analysis of plasticity in cyclic compression precracking — •mohamed amine faham, nathalie limodin, jean françois witz, and jérôme hosdez — Univ. Lille, CNRS, Centrale Lille, UMR 9013 - LaMcube - Laboratoire de Mécanique, Multiphysique, Multiéchelle, F-59000 Lille, France

Determining whether a defect will grow or not is of outmost importance particularly for railway axles. In this context, compressive precracking is an interesting procedure to get fatigue crack growth threshold. Using this method, specimens are precracked with both maximum and minimum compressive loads. This study uses fracture mechanics analysis, digital image correlation (DIC) and finite element method (FEM) to assess compressive plastic zone and precrack length ahead of a SENT specimen notch.

The DIC strain field in the direction of loading shows the evolution of the monotonic compressive zone ahead of the notch with increasing load. Other techniques were used to assess the plasticity ahead of the notch and to verify DIC vertical strain field results. One technique consists of projecting (in the least squares sense) the measured DIC displacement fields on Williams’ basis. The difference between the DIC vertical displacement field and the analytical one highlights the plasticity in the notch region. A coupled DIC-FEM simulation with boundary conditions issued from DIC displacement fields applied on a numerical model of the specimen with inelastic material behavior was done in order to verify the extent of the compressive plastic zone and to estimate the compressive precrack length.