X-ray computed -tomography: a tool for the characterization of fatigue defect population in a polychloroprene rubber.

Abstract: As elastomeric materials are heterogeneous by nature, their fatigue behavior is strongly driven by the initiation and the growth of cavities. The explanations on the microscopic mechanisms are usually supported by SEM observations. SEM is a 2D destructive technique that can induce artifacts and is not suitable to analyze 3D phenomena. Moreover, the time needed to observe a single slice prevents from scanning a whole massive sample. In this study X-ray micro-tomography is used. This non destructive method has already been widely applied to elastomeric materials to control the fillers size and dispersion or to analyze the cavitation induced under high hydrostatic pressure fatigue loading, for example. Here, this technique is used with a good resolution to analyze the evolution of the defects population during a fatigue campaign on hourglass-shaped specimens. The initiation and propagation mechanisms are clearly illustrated on 3D observations, and the influences of the maximum principal strain and of the number of cycles on several damage parameters (size repartition, porosity, defect volumic density) are investigated. A scenario for the fatigue damage evolution is proposed and some fatigue initiation criteria are finally discussed with the help of the micro-structural measurements. [Copyright &y& Elsevier]