The paper investigates the scale effect in relatively thin welded joints subjected to fatigue loading. In scientific literature, the fatigue behaviour of arc welded joints is usually divided into two groups: thick and thin joints. A cut-off thickness, typically in the range of 13 mm to 22 mm, is introduced; under such cut-off value the design fatigue strength does not increase by decreasing thickness. Despite this common approach, in the present paper, by means of the implicit gradient method, the concept of cut-off thickness is revised and a single numerical procedure is proposed regardless of the thickness of the joint. In particular, classical non-load carrying and load carrying cruciform joints made of steel are considered in the numerical analysis. On the basis of many experimental comparisons, the implicit gradient approach seems able to capture the fatigue strength of welded joints also when only a few millimeters in thickness. Furthermore, in the case of load carrying cruciform joints, by scaling the weld geometry, it is discussed when the failure initiation site moves from the weld toe to the root and vice versa as a function of the thickness.

Thickness effect in welded structures with the implicit gradient approach

TOVO, Roberto;LIVIERI, Paolo
2011

Abstract

The paper investigates the scale effect in relatively thin welded joints subjected to fatigue loading. In scientific literature, the fatigue behaviour of arc welded joints is usually divided into two groups: thick and thin joints. A cut-off thickness, typically in the range of 13 mm to 22 mm, is introduced; under such cut-off value the design fatigue strength does not increase by decreasing thickness. Despite this common approach, in the present paper, by means of the implicit gradient method, the concept of cut-off thickness is revised and a single numerical procedure is proposed regardless of the thickness of the joint. In particular, classical non-load carrying and load carrying cruciform joints made of steel are considered in the numerical analysis. On the basis of many experimental comparisons, the implicit gradient approach seems able to capture the fatigue strength of welded joints also when only a few millimeters in thickness. Furthermore, in the case of load carrying cruciform joints, by scaling the weld geometry, it is discussed when the failure initiation site moves from the weld toe to the root and vice versa as a function of the thickness.
2011
implicit gradient; fatigue; thin welded joint
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11392/1531787
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