PSI - Issue 35

Onkar Salunkhe et al. / Procedia Structural Integrity 35 (2022) 261–268 Onkar Salunkhe, Parag Tandaiya / Structural Integrity Procedia 00 (2021) 000–000

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(b)

(c)

(d)

Fig. 3. (a) Contour plot of maximum principal logarithmic plastic strain ln λ p 1 for uncoated monolithic plane strain model at failure, (b) Contour plot of damage variable in uncoated model wherein the damaged elements have been deleted showing the formation of a crack at failure, (c) Contour plot of maximum principal logarithmic plastic strain ln λ p 1 for coated model at failure strain and, (d) Contour plot of equivalent plastic strain in the Copper coating at failure strain.

Fig. 4. Comparison of nominal stress-strain curves for plane strain compression of uncoated / monolithic BMG and thin film Copper coated BMG composite having 100 µ m Copper coating.

to mesh the geometry. The model dimensions used are 1 mm × 2 mm with 1 mm thickness for uncoated monolithic BMG model and a thin Copper coating of thickness 100 µ m is added to the BMG composite model. Because of the plane strain constraint, the BMG is likely to fail at a lower strain than the 3D slab model. Compressive displacements are applied on the top nodes at a quasi-static strain rate of 10 − 4 s − 1 . As seen in Fig. 3(a), use of the ductile damage model promotes intense strain localization which leads to cracking as seen in Fig. 3(b) and (c). However, it is seen that thin ductile Copper coating leads to more homogenization of plastic strain in the specimen (see Fig. 3(c)) and less severity of damage in the shear band. The coating prevents the catastrophic propagation of the shear band as seen in Fig. 3(d). However, as seen from Fig. 4, the prediction of strain to failure is unchanged for uncoated BMG and Copper coated BMG composite from plane strain simulations.

3.4. Axisymmetric simulations of uniaxial compression of Copper coated BMG composite

An axisymmetric cylinder model is created with dimensions of 2 mm diameter and 4 mm height. CAX4R element type is used to mesh the model. The material parameters used are of Vitreloy-105 BMG mentioned in Section 3.5. Both uncoated monolithic BMG and Copper coated BMG composite models are simulated under uniaxial compression deformation. The thickness of Copper coating is taken as 100 µ m. Figure 5(a) indicates formation of di ff used shear bands inside the monolithic BMG just at the onset of failure. Figure 5(b) indicates that a crack grows inside the