Micro-mechanical numerical analyses on the effect of stress state on ductile damage under dynamic loading conditions

Abstract

The paper deals with the effect of stress state on the dynamic damage behavior of ductile materials. The rate-and temperature-dependent continuum damage model has been enhanced to take into account the influence of the stress triaxiality and the Lode parameter on damage condition and on rate equations of damage strains. Different branches of these criteria depending on the current stress state are considered based on different damage and failure processes on the micro-level. To get more insight in the dynamic damage and fracture processes micro-mechanical behavior of void-containing representative volume elements have been analyzed numerically. These three-dimensional numerical simulations based on different dynamic loading conditions take into account a wide range of stress states in tension, shear and compression domains. Based on the numerical results general trends of dynamic damage and failure behavior can be shown and stress-state-dependent equations for damage criteria and for the formation of damage strains can be proposed.

Metamodeling of structural failure: Case study of API S-135 steel tube cut in BOP

“…Among them, the simplest is RSM, which is basically a polynomial regression. Independently of the adopted technique, the general form of the method results in an approximation of the exact solution, 𝑦 = 𝑦 + 𝜖 (47) where, for a given state 𝑖 of input variables, 𝑦 is the exact solution from the numerical model, 𝑦 is the approximate response surface and 𝜖 is the error between the exact solution and the approximation. The approximations 𝑦 are those that minimize the sum of squared errors (SSE), defined as,…”

“…where 𝜇 is the Lode parameter Gerke, Adulyasak and Brünig (2017) [46], Brünig, Gerke and Tix (2018) [47] and in Brünig, Gerke and Schmidt (2016, 2016a, 2018) [48], [49], [50].…”

“…Since various important mechanisms occur at the atomic scale (dislocations or grain boundaries) and microscale (hard precipitates or voids), models such as those presented in Table 4 are essential to enhance the general understanding of damage and ductile failure process. Nowadays, numerical simulations of unit-cells with single voids are still discussed in the literature as, for example, Brünig, Gerke and Tix (2018) [47]. However, these models have significant simplifications and are not applicable when modeling real structures.…”