Experiments with the X0-specimen on the effect of non-proportional loading paths on damage and fracture mechanisms in aluminum alloys

The paper deals with an experimental series with the new biaxial cruciform X0-specimen to study the stress state and loading path dependence of ductile damage and fracture. The ongoing material deterioration is studied experimentally to develop and validate corresponding phenomenological damage and fracture models. In this context the new cruciform X0-specimen has been proposed which is characterized by four independent notched regions where inelastic deformations as well as damage and fracture are localized. The specimen allows investigation of a wide range of stress states and can be applied for different loading paths. A series of biaxial experiments with proportional and corresponding non-proportional loading paths has been performed and the experimental technique with different loading histories is presented in detail. The experiments have been monitored by a special six camera DIC setting allowing even the analysis of the specimen behavior in thickness direction. Furthermore, the fracture surfaces have been analyzed by scanning electron microscopy (SEM). The results based on proportional and non-proportional loading paths clearly show that damage and fracture processes are load-path-dependent. (C) 2019 Elsevier Ltd. All rights reserved.