Non‐local line method for notched elements with use of effective length calculated in an elasto‐plastic condition

• Published in: Fatigue & fracture of engineering materials & structures Vol. 40; no. 1; pp. 89 - 102
• Main Authors: Krzyżak, D., Robak, G., Łagoda, T.
• Format: Journal Article
• Language: English
• Published: Oxford Wiley Subscription Services, Inc 01.01.2017
• Subjects: critical plane; effective length; effective stress distribution; Equivalence; Fatigue (materials); Fatigue life; Finite element analysis; Mathematical models; non‐local methods; notch effect; Notches; Planes; Shear stress; Simulation; stress gradient; Structural steels; Weight function
• ISSN: 8756-758X; 1460-2695
• DOI: 10.1111/ffe.12478

The paper presents a non‐local line method used to the fatigue life calculation of notched elements. The presented method is based on the concept of an effective length which determines the size of the equivalent fatigue zone. Effective values of normal stress calculated in the critical plane with a weight function were applied when determining the equivalent fatigue zone. Simulation studies were performed for two types of steel and two types of loading. Five different series of tests and simulations were used. Experimental studies were carried out for 40 HM‐T and EA4T steels. These materials are used in railway industry, including the manufacturing of coupling bars. The notched test specimens contained notches with a tip radius of 0.2, 0.5, 0.8 and 1 mm. Stress calculations were performed using the finite element method by adopting cyclic material properties described by the model of a multi‐linear hardening. Non‐local calculations were performed in a defined critical plane for normal stress distribution and a weight function. As a result, the function of variation of the effective length depending on the loading level and geometry of the notch has been determined.