Numerical Analyses of Stress-triaxiality-dependent Inelastic Deformation Behavior of Aluminum Alloys

Abstract

The article deals with the effect of stress triaxiality on the inelastic deformation behavior of aluminum alloys. The proposed continuum model takes into account a stress-triaxiality-dependent yield condition as well as a damage criterion with different branches corresponding to various damage modes depending on the stress triaxiality and the Lode parameter. Numerical simulations of experiments with smooth and pre-notched tension and shear specimens are presented covering a wide range of stress triaxialities. Numerical results show good agreement with available experimental data. The analyses allow verification of the macroscopic model and identification of material parameters.

Stress‐triaxiality‐dependent modeling of ductile damage and fracture behavior

“…In addition, a damage criterion is proposed describing the onset and continuation of damage. Taking into account different failure mechanisms leading to final fracture, a wide range of stress triaxialities with three different branches is considered [5,7]: damage is characterized by micro-shear-cracks for negative stress triaxialities, by void growth and coalescence for large positive stress triaxialities and by a combination of these basic mechanisms for lower positive stress triaxialities. In the hydrostatic pressure regime, a cut-off-value of stress triaxiality is taken into account below which damage and fracture do not occur in metals.…”

“…The transferability of the identified parameters to multiaxial stress states with different stress triaxialities is not always controlled and, thus, seems to be questionable. Attempts to take into account the effect of stress triaxiality in their continuum approaches have been presented in the literature [1][2][3][4][5] based on tension tests with pre-notched specimens.…”

A Continuum Damage Model Based on Experiments and Numerical Simulations—A Review

“…In this context, in the last years various damage models have been published based on experimental observations as well as on multi-scale approaches (Brünig 2001(Brünig , 2003Gurson 1977;Murakami and Ohno 1981;Lemaitre 1996;Voyiadjis and Kattan 1999). In this context, Brünig et al (2011b;; Brünig and Gerke (2011) have proposed a generalized and thermodynamically consistent, phenomenological continuum damage model which has been implemented as user-defined material subroutines in commercial finite element programs allowing analyses of static and dynamic problems in differently loaded metal specimens. To be able to detect stress triaxiality dependence of the constitutive equations tension tests with carefully designed specimens have been developed.…”

“…To be able to detect stress triaxiality dependence of the constitutive equations tension tests with carefully designed specimens have been developed. For example, differently pre-notched specimens and corresponding numerical simulations have been used by Bai and Wierzbicki (2008); Bao and Wierzbicki (2004); Becker et al (1988); Bonora et al (2005); Brünig et al (2011b;; Dunand and Mohr (2011);Gao et al (2010). However, these experiments with unnotched and differently notched flat specimens showed stress triaxialities only in a small region of positive values.…”

Load Bearing Capacity of a Dented Aluminum Pipe Subjected to Internal Pressure Considering the Effect of Ductile Damage

“…Several threedimensional micro-mechanical numerical analyses are performed for covering a wide range of stress triaxialities and Lode parameters in tension, shear and compression domains (Brünig et al, 2013). Also the effect of stress triaxiality on the inelastic deformation behavior of aluminum alloys for smooth and pre-notched tensile and shear specimens were studied experimentally and numerically by Brünig et al (2011).…”