Influence of Weld-Porosity Defects on Fatigue Strength of AH36 Butt Joints Used in Ship Structures

: Experimental tests were carried out to assess the fatigue strength of four types of welded
joints, made of AH36 steel and used for ship structures. The joints differ for the presence of weld
defects and for the thickness value. Fatigue tests were carried out applying axial cyclic loads at
a frequency of 20 Hz and at a stress ratio R = 0.5. The temperature e increment of the specimen
surface was detected during the load application by means of an infrared camera. The analysis of
the thermographic images allowed the assessment of both the fatigue strength of the welded joints,
applying the rapid thermographic method, and the S-N curve by the energy approach. Moreover, 3D
computed tomography was used for the analysis of the defective welded joints.