Hole cold expansion is a technique widelyudused to improve the fatigue life of components withudholes, e.g. bolted or riveted joints. As it has been demonstratedudin literature by analytical, numerical and experimentaludanalyses carried out by several authors, theudcompressive residual stresses introduced by the hole coldudexpansion have a beneficial influence on both the staticudand the fatigue strength of the treated component, becauseudthey reduce significantly the typical stress peaksudaround the hole due to stress concentration. In the literature,udvarious analyses of the residual stresses introducedudby the hole cold expansion have been performed byudusing several methods such as X-ray diffraction, neutronuddiffraction and the modified Sachs method. Unfortunately,udall these method are affected by some limitations: lowudmeasurement depth (X-ray method), complex measurementudprocedure (neutron diffraction method) and approximateudformulation (Sachs method). In order to overcomeudsuch drawbacks, in this study a new mechanical method,udbased on an innovative extension of the “rectilinearudgroove method” associated with the classical “integraludmethod” calculation procedure, is proposed. Experimentaludassessment of the proposed method has been performedudby using aluminum 5083 H321 specimens with holesudsubjected to various levels of cold expansion.
展开▼
