Plastic size effects in single crystals are investigated by using finite strain and small strain discrete dislocation plasticity to analyse the response of cantilever beam specimens. Crystals with both one and two act...Plastic size effects in single crystals are investigated by using finite strain and small strain discrete dislocation plasticity to analyse the response of cantilever beam specimens. Crystals with both one and two active slip systems are analysed, as well as specimens with different beam aspect ratios. Over the range of specimen sizes analysed here,the bending stress versus applied tip displacement response has a strong hardening plastic component. This hardening rate increases with decreasing specimen size. The hardening rates are slightly lower when the finite strain discrete dislocation plasticity（DDP） formulation is employed as curving of the slip planes is accounted for in the finite strain formulation.This relaxes the back-stresses in the dislocation pile-ups and thereby reduces the hardening rate. Our calculations show that in line with the pure bending case, the bending stress in cantilever bending displays a plastic size dependence. However, unlike pure bending, the bending flow strength of the larger aspect ratio cantilever beams is appreciably smaller.This is attributed to the fact that for the same applied bending stress, longer beams have lower shear forces acting upon them and this results in a lower density of statistically stored dislocations.展开更多
In this paper, the energy absorption mechanism of empty and foam-filled aluminum tubes with different cross-sections （circular, square and elliptic） under bending load is investigated numerically. The load-displacem...In this paper, the energy absorption mechanism of empty and foam-filled aluminum tubes with different cross-sections （circular, square and elliptic） under bending load is investigated numerically. The load-displacement curves of the present simulations are in very good agreement with those of published experimental data. Here, the existing analytical formulations are reviewed and compared with experimental results. In addition, the effects of different cross-sections and wall thicknesses on the energy absorption capacity and specific energy absorption of these tubes are fully investigated. The results indicate that the energy absorption of an elliptic foam-filled tube with 1.5 mm and 2 mm thicknesses increases about 45% and 73% in comparison with a square one, respectively.展开更多
基金support from Eindhoven University of Technology is gratefully acknowledged
文摘Plastic size effects in single crystals are investigated by using finite strain and small strain discrete dislocation plasticity to analyse the response of cantilever beam specimens. Crystals with both one and two active slip systems are analysed, as well as specimens with different beam aspect ratios. Over the range of specimen sizes analysed here,the bending stress versus applied tip displacement response has a strong hardening plastic component. This hardening rate increases with decreasing specimen size. The hardening rates are slightly lower when the finite strain discrete dislocation plasticity（DDP） formulation is employed as curving of the slip planes is accounted for in the finite strain formulation.This relaxes the back-stresses in the dislocation pile-ups and thereby reduces the hardening rate. Our calculations show that in line with the pure bending case, the bending stress in cantilever bending displays a plastic size dependence. However, unlike pure bending, the bending flow strength of the larger aspect ratio cantilever beams is appreciably smaller.This is attributed to the fact that for the same applied bending stress, longer beams have lower shear forces acting upon them and this results in a lower density of statistically stored dislocations.
文摘In this paper, the energy absorption mechanism of empty and foam-filled aluminum tubes with different cross-sections （circular, square and elliptic） under bending load is investigated numerically. The load-displacement curves of the present simulations are in very good agreement with those of published experimental data. Here, the existing analytical formulations are reviewed and compared with experimental results. In addition, the effects of different cross-sections and wall thicknesses on the energy absorption capacity and specific energy absorption of these tubes are fully investigated. The results indicate that the energy absorption of an elliptic foam-filled tube with 1.5 mm and 2 mm thicknesses increases about 45% and 73% in comparison with a square one, respectively.
