A study of microcrack formation in multiphase steel using representative volume element and damage mechanics

Experimental and numerical investigation of failure mode in geometrically imperfect DP590 steel

“…Figure 9 shows the engineering stress-strain curve obtained from the micromechanical RVE model using the boundary conditions described in Section 2.2, and the distribution of equivalent plastic strain at the selected times. Like the stress-strain curves observed by Uthaisangsuk et al [18] and Ramazani et al [20], the stress-strain curve observed in this study was slightly underestimated in the 2D RVE simulation. In addition, comparing the engineering stress-strain curves from experiment and simulation, it could be found that during the uniform deformation period the curves correlate well with each other, but show large deviation after the loss of uniform deformation due to the lack of considera- tion of necking phenomenon in the RVE model.…”

“…From the beginning of time (d), in parts of the microstructure that sustained high displacement and rotation, severe strain concentration occurred in the ferrite domain adjacent to the boundary of ferrite and martensite area. According to the work of Uthaisangsuk et al [18], the martensite decohesion typically takes place after obtaining some deformation. Thus at the location with severe strain concentration debonding between ferrite and martensite was anticipated to occur following this assumption, since no cohesive or surface elements were used in the current study debonding phenomenon could not be accurately predicted.…”

“…Accordingly, the classical Marciniak-Kucaynski model [12] having initial geometrical imperfections that trigger instability [13,14] is used to predict the localized necking , and the damage-and void-growth-induced bifurcation condition in the popular Gurson-Tvergaard-Needleman (GTN) model can be analytically formulated as material instability occurring on a constitutive level [15]. Uthaisangsuk et al [16][17][18], Vajragupta et al [19], and Ramazani et al [20] used the microstructure-based RVEs to evaluate microstructure deformation and failure initiation from the mesoscale, addressing martensite cracking using an extended finite element method (XFEM). In addition, a cohesive zone model was used to study the debonding analysis of the martensite islands in the ferrite parent phase, and the GTN model was used to describe the ductile damage of the ferrite matrix.…”

Microstructure based prediction of strain hardening behavior of dual phase steels

“…Nevertheless, it must be noted that the calculations in this work were based on a 2D plain strain assumption. A 3D calculation should provide a more precise flow curve prediction, as discussed in [17,20].…”

“…During deformation a network-like structure of interrupted bands of high strain develops that could be assumed to be the primary sites of damage initiation. Otherwise, many researchers used micromechanical modeling to investigate and describe mechanical behavior of steels consisting of different constituents [16][17][18][19][20]. By producing DP steels austenite transforms to martensite during quenching step that causes a volume expansion.…”