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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(a) (b) Fig. 6. (a) As-cast and coated (right) BMG specimens after failure (taken from Sun et al. (2016)) (b) Experimental stress-strain curves of as-cast and coated Vitreloy-105 BMG specimens (taken from Sun et al. (2016)).

(a) (c) Fig. 7. (a) Comparison plot of experimental and simulation nominal stress-strain curves for uncoated cylinder model for calibration, (b) Comparison plot of nominal stress-strain curves from the simulation for uncoated / monolithic BMG and Copper coated BMG composite and, (c) Contour plot of maximum principal logarithmic plastic strain ln λ p 1 for coated cylinder model at an overall strain of 5%. (b)

band is formed at an angle of about 45 ◦ to the loading axis in the coated BMG composite. The coating just delays the failure and increase the malleability of the composite.

4. Conclusions

BMGs, being amorphous, do not exhibit yielding by necking or by ductile deformation. BMGs are more likely to fail by shearing. BMGs have more yield strength in compression than in tension which is the property of pressure sensitive plastic materials. Uniaxial compression and tension simulations of 3D Prismatic bar of Monolithic BMG matrix are performed. Plane strain slab model and axisymmetric cylinder model with copper coating on BMG matrix are also simulated. Formation of dominant shear band at an angle of about 45° in the plane of maximum shear which initiates the damage in the BMG matrix is observed. This results in fracture by shear cracking, which is observed in the experiments and is predicted correctly in the simulations. The fracture of BMGs is confirmed by traversing of dominant shear band through the entire cross section of the model. Plane strain slab model does not show enhance ment in malleability. But axisymmetric and 3D cylinder models show malleability enhancement by about 2% at the expense of overall decreased yield strength which is in qualitative agreement with experimental observations reported in literature. This enhancement is because the Copper coating restricts the propagation of dominant shear band and arrests the crack growth inside the shear band.