Low cycle fatigue strength assessment of cruciform welded joints

Abstract

This paper presents the results of an experimental study on the low cycle fatigue strength of cruciform welded joints. Tests were performed on 22 specimens of three different categories, namely full-penetration, partial-penetration and fillet welded cruciform joints. These tests consisted basically of imposing on each specimen a constant amplitude cyclic displacement history in the plastic range of the material behaviour. The experimental testing procedure is described and the results are presented. The unified approach for low and high cycle fatigue strength assessment proposed by Ballio and Castiglioni [1]is applied to the test results. Such approach leads to the conclusion that the same set of Wöhler ( S– N) lines [2]usually given in recommendations [3]for high cycle fatigue can be also applicable in the low cycle fatigue range. It is demonstrated that the proposed damage model allows prediction of the number of cycles to failure for the specimens, at each given cycle amplitude, with a notable accuracy.