PSI - Issue 13

Per Hansson / Procedia Structural Integrity 13 (2018) 837–842

842

Per Hansson/ Structural Integrity Procedia 00 (2018) 000 – 000

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Fig. 7. Events during the first load cycle for a beam with a centrally placed void with δ xmax =10.85Å, cf. Fig. 5. The atomic snapshots are color coded by the CSP with blue corresponding to 0 and red above 30.

Fig. 8. Events during the first load cycle for a beam with an edge defect with δ xmax = 9.941Å, cf. Fig. 5. The atomic snapshots are color coded by the CSP with blue corresponding to 0 and red above 30. 3. Conclusions It was found that an increase in temperature led to initiation of plastic deformation at lower strain as well as in lower resistance to fatigue loading. It was also found that a defect in the beam lowered the strain at initiation of plastic deformation and lowered the resistance to fatigue failure significantly. Also the behavior for the case of a void changed with temperature, as the void collapsed during loading for the case T=300K , not found at =0.01K. For some of the casess a steady state, with lower stress amplitude, was found already in the second cycle, after an initial plastic cycle with higher stress values. This was observed in the cases where no additional plasticity developed outside the first cycle. For other cases no steady state was not obtained, eventually leading to rupture of the beam after some cycles, although in some cases the plastic deformation in the first cycle was quite limited. Finally it was found that a defect in the beam strongly reduced the resistance both to plastic initiation during monotonic loading and the resistance to fatigue loading. It was found that the least resistance to plastic initiation was the case of a void and the least resistance to fatigue failure was the case of an edge defect. Ahadi A, Hansson P. and Melin S, 2016. Defect sensitivity of single-crystal nano-sized Cu beams, Procedia Structural Integrity 2, 1351-1358. Ahmed W and Ali N (ed.), 2014. Manufacturing nanostructures, One Central Press, ISBN (eBook) 9781910086070. Ellad B. T. and Miller R. E, 2011. Modeling Materials Continuum, Atomistic and Multiscale Techniques. Cambridge University press. Foiles S. M, Baskes M. I and Daw M. S, 1986. Embedded-atom-method functions for the fcc metals Cu, Ag, Au, Ni, Pd, Pt, and their alloys Physical review B, Vol. 33, No. 12 Holian BL and Ravelo R, 1995. Fracture simulations using large-scale molecular-dynamics. Phys. Rev. B 51 17 11275-11288. Hommel, M.and Kraft, O, 2001. Deformation behavior of thin cupper films on deformable substrates. Acta Mater. 49 3935-47. Kelchner, Plimpton and Hamilton, 1998. Dislocation nucleation and defect structure during surface indentation Phys. Rev. B 58:11085-8. Olsson PAT, Melin S and Persson C, 2007. Atomistic simulations of tensile and bending properties of single-crystal bcc iron nanobeams. Phys. Rev. B 76 224112. Stukowski A, 2010.Visualization and analysis of atomistic simulation data with OVITO – the Open Visualization Tool. Modelling Simul. Mater. Sci. Eng. 18. Uhnakova A, Machova A, Hora P and Cervena O, 2014. Growth of a brittle crack (001) in 3D bcc iron crystal with a Cu nano-particle. Computational Materials Science. Roc. 83, 229-234. ISSN 0927-0256 Zhou LG and Huang HC, 2004. Appl. Phys. Lett. 84, 1940 References