PSI - Issue 42

Lucas Mangas Araújo et al. / Procedia Structural Integrity 42 (2022) 1591–1599 Author name / Structural Integ ity Procedia 00 (2019) 000 – 000

1594 4

(7)

with (.) representing the residual equation of the variable (·) . 3. Numerical results 3.1. Experimental data and material.

The SAE 1045 steel was the material chosen for the evaluation of the stress invariants effects. This alloy possesses a considerably large amount of Ductile Fracture, Ultra-Low and Low Cycle Fatigue data available in the literature [1, 2], besides from its industrial relevance. For example, this alloy is important in machining process, both as a cutting tool and as the machined material for engineering applications [10, 11]. Bai [1] conducted a series of monotonic and ULCF tests on butterfly specimens to investigate the effects of triaxiality η and normalized third invariant ξ on this material. All the tests were displacement controlled and carried out until fracture. Figure 2 displays schematically how these experiments were elaborated and some of the load conditions considered.

Fig. 2. Experiments performed on SAE 1045 butterfly specimens. On the left, the specimen regions that are fixed and where the prescribed displacement are applied. On the right, the loading directions investigated. Adapted from Bai [1].

Table 1 summarizes the material parameters for isotropic and kinematic hardening.