Application of the weakest link analysis to the area of fatigue design of steel welded joints

• Probabilistic model for fatigue life evaluation of steel welded joints is presented.
• Failure probability evaluation is based on the reliability theory and the weakest link concept.
• Failure probability is defined by Weibull distribution with shape and scale parameters.
• The efficient material S–N curve is introduced as suitable for a variety of joints.
• Validation process yielded similar scale parameter values for two different geometries.

A new approach in the area of fatigue life assessment of steel welded joints is being proposed with the following features: (i) methodology of fatigue life calculation is independent from geometry of welded element; (ii) fatigue life assessment is based on fatigue characteristic of introduced efficient material – suitable for different steel welded joints; (iii) the fatigue life assessment is carried on the desired level of failure probability.In the proposed method a material volume surrounding the weld is divided into volume elements and regarded as a serial system having its definition in the reliability theory (the weakest link concept). Failure probability distribution of the welded structure is characterized by the proposed S–N curve for efficient material and the shape parameter introduced to describe the volume effect.