Abstract
Low cycle fatigue strength of welded joints was investigated by means of newly developed fatigue testing system in which image analysis technique was applied to measure the strain of specimens. It was validated that the strain measured by the image analysis was almost equal to measured value by strain gauge, and the low cycle fatigue strength of steel plate without welding was in good agreement with the results reported in former researches. After verifying the testing system, fatigue tests were carried out on welded joint specimens. The test results indicated that the low cycle fatigue strength of welded joints was much lower than that of plain material, and fatigue life was reduced by half.
