Evaluation of Fatigue Strength of Welded Joints by Local Strain Measurements at Weld Toe

2007 ◽  
pp. 701-704
Author(s):  
C. Casavola ◽  
C. Pappalettere
Keyword(s):  
Fatigue Strength ◽  
Welded Joints ◽  
Local Strain ◽  
Strain Measurements ◽  
Weld Toe

Evaluation of Fatigue Strength of Welded Joints by Local Strain Measurements at Weld Toe

2007 ◽  
Vol 348-349 ◽  
pp. 701-704
Author(s):  
C. Casavola ◽  
C. Pappalettere
Keyword(s):  
Fatigue Strength ◽  
Working Conditions ◽  
Welded Joints ◽  
Local Strain ◽  
Industrial Applications ◽  
Welded Structures ◽  
Strain Measurements ◽  
Weld Toe ◽  
Strain Magnitude ◽  
The Many

The fatigue strength of real welded structures neither can be covered by formulae or theoretical arguments, nor simply deducted by studying a complex assembly through its elementary components because of the many interactions among different factors governing the phenomenon. In view of this, the support of experimental observations and practical procedures to evaluate the stress/strain magnitude that could lead some components to unsafe working conditions should be preferred, especially in industrial applications where fast and reliable responses are strongly needed.

Local strain for fatigue strength of welded structures

2001 ◽  
Vol 36 (6) ◽  
pp. 605-610 ◽  
Author(s):  
V Dattoma ◽  
C Pappalettere
Keyword(s):  
Fatigue Strength ◽  
Welded Joints ◽  
Structural Integrity ◽  
Strain Curve ◽  
Local Strain ◽  
Fatigue Design ◽  
Curve Versus ◽  
Weld Toe ◽  
Stress Ratios ◽  
Tip Radius

Field criteria, which are usually applied in fracture mechanics to ensure the structural integrity of cracked components, are extended to the fatigue design of welded joints, whose weld toe can be assimilated to a notch with a small tip radius. In particular, fatigue strength in terms of strain rather than of stress has been determined by applying stress cycles with different stress ratios R = σmin/σmax. Finally, for the evaluation of the fatigue strength of welded joints in structural steel, a strain curve versus different R ratios is given to be compared with the service measured local strain at the weld toe.

Fatigue Design of Welded Joints by Local Approaches: Comparison between Fictitious Notch Rounding and Strain Energy Averaging

2007 ◽  
Vol 348-349 ◽  
pp. 449-452 ◽  
Author(s):  
Paolo Lazzarin ◽  
Filippo Berto ◽  
D. Radaj
Keyword(s):  
Welded Joints ◽  
Strain Energy ◽  
Control Volume ◽  
Local Strain ◽  
Stress Distributions ◽  
Good Correspondence ◽  
Load Carrying ◽  
Weld Toe ◽  
Weld Root ◽  
Coarse Meshes

The paper demonstrates the close correspondence between two local approaches to assess the fatigue strength of welded joints: Radaj’s approach based on fictitious notch rounding and a recently proposed approach based on the local strain energy density (SED) averaged over a given control volume. This volume surrounds the weld root or weld toe, both modelled as sharp (zero radius) V-notches with different opening angles. The two approaches are applied to load carrying and non-load carrying cruciform joints and the theoretical fatigue notch factors Kf are compared. The SED averaged over the control volume is determined from finite element models with very fine meshes, as typically designed to evaluate the intensity of the asymptotic stress distributions, and also from coarse meshes, showing a surprisingly good correspondence.

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