Experiments on Low–Cycle Ductile Damage and Failure Under Biaxial Loading Conditions

Abstract

Background

The damage and failure behavior of ductile metals depends on the stress state as well as on the loading history. Biaxial experiments with suitable specimens can be used to targeted generate different loading conditions, thus allowing the investigation of a wide variety of load cycles with different stress states.

Objective

In the biaxial experiments with the newly presented HC-specimen cyclic shear loads are superimposed by various constant compressive and tensile loads. Buckling during compressive loading in both axes is avoided by an additional newly introduced downholder.

Methods

The strain fields at the surfaces of the biaxial specimens are evaluated by digital image correlation (DIC), and after failure the corresponding fracture surfaces are analyzed by scanning electron microscopy (SEM). Associated numerical simulations employing the presented material model provide information on the current stress states.

Results

The introduced downholder successfully prevents buckling during compressive loading. The strain fields detect a clear influence of the shear direction and a tensile superposition of the cyclic shear load leads to more brittle and a compressive superposition to more ductile behavior. The accompanying numerical calculations reveal the associated, different stress states.

Conclusions

The new experimental program with biaxially loaded specimens for the investigation of damage and failure behavior under cyclic loading enables the targeted examination of a wide variety of load cycles and is thus suitable for the comprehensive analysis of these phenomena.