Creep‐fracture resistance parameters determination based on stress and ductility damage models

Abstract

The stress, strain rate, and process zone with respect to the creep‐crack growth in pure modes I and II are analysed by using damage‐evolution equations. The damage models for the fracture of the process zone are represented using a stress‐ and ductility‐based formulation. According to the stress‐based model, 2 expressions are proposed to describe the stress‐sensitive nature of a multiaxial rupture behaviour. Following the ductility model, new multiaxial failure strain conditions are derived. Both damage‐free and defective creeping solids have been studied. The variations in the creep stress or strain and crack‐tip governing parameter in terms of the creep In‐integral with respect to time and the evolution of creep damage are analysed using a finite element model. The effect of the introduced creep stress intensity factor as a function of the creep time, loading biaxiality, and creep damage models is discussed in detail.

Characterization of stress-strain state in gas turbine engine compressor disc taking into account damage accumulation

“…Temperature, °С In this study, the model proposed by Shlyannikov and Tumanov for the damage accumulation rate [12,13] was used to assess the creep damage behaviour:…”

“…Knowing only the constants of the Norton law equation and the time to fracture at least at one level of the effective nominal stresses is enough to determine the constants of Eqn. (2) [12,13]. Eqn.…”

The effect of creep damage model formulation on crack path prediction

“…Similarly Eq. (2), Shlyannikov and Tumanov [3] introduced a model for the rate of accumulation of stress-based creep damage as a function of multi-axial stress function…”

Cruciform specimens for the determination of crack growth behaviour in biaxial stress fields: calculation of K-factors

“…Refs. [7][8][9][10][11][12][13][14][15][16][17]. As a result of the different specimen designs, the K-solution has to be computed for each specimen design by FE-calculations considering the individual crack paths and the material.…”

“…4b is given in Eq. (16). The course of the fit functions Y fit (a) or Y fit y (a) was compared with the values of Y (a) or Y y (a) determined for the straight crack paths using Eq.…”