Surface originated kink bands consist of an important failure mode for fibre-reinforced compo- sites under compression. The mechanical behavior of the fibre bridging kink bands is explored herein in the context of the...Surface originated kink bands consist of an important failure mode for fibre-reinforced compo- sites under compression. The mechanical behavior of the fibre bridging kink bands is explored herein in the context of the post-microbuckling theory. Expressions of bridging force are obtained for the entire postbuckling process of the fibres exhibiting weak or strong hardening. The postbuckling formulation of the fibres is applied to yield the toughness increment due to the advancing kink bands, and consequently leads to a quantitative pre- diction on the overall compressive stress strain curves of the fibre-reinforced composites.展开更多
This paper suggests the asymmetric-plastic theory of crystalline solids concerning the plastic rotation of crystal. The deformation of crystalline solids undergoes three microprocesses, lattice distortion, slip over a...This paper suggests the asymmetric-plastic theory of crystalline solids concerning the plastic rotation of crystal. The deformation of crystalline solids undergoes three microprocesses, lattice distortion, slip over active crystallographic planes and the rotation- of the crystal. In the asymmetric-plastic theory of crystal suggested, the corotational rates of symmetric Cauchy stress and moment stress correspond to the rates of elastic strain and the gradient of the rotational rate of the crystal respectively. The Schmid yield condition and Prager's consistency condition incorporating antisymmetric stress are formulated. Then the asymmetric-plastic model of crystalline solids is applied for the investigation of the onset of kink band by a standard stability analysis. The orientation of the kink band is perpendicular to the primary slip system. The width of the kink band is the function of the ''characteristic length'' of the microstructure of metal materials.展开更多
For the development of high-strength Mg alloys,active use of Laves phases such as C14-type Mg_(2)Yb and Mg_(2)Ca is strongly expected.However,the brittleness of the Laves phases is the biggest obstacle to it.We first ...For the development of high-strength Mg alloys,active use of Laves phases such as C14-type Mg_(2)Yb and Mg_(2)Ca is strongly expected.However,the brittleness of the Laves phases is the biggest obstacle to it.We first found that kink-band formation can be induced in directionally solidified Mg/Mg_(2)Yb and Mg/Mg_(2)Ca eutectic lamellar alloys when a stress is applied parallel to the lamellar interface,leading to a high yield stress accompanied with ductility.That is,microstructural control can induce a new deformation mode that is not activated in the constituent phases,thereby inducing ductility.It was clarified that the geometric relationship between the operative slip plane in the constituent phases and the lamellar interface,and the microstructural features that provide kink-band nucleation sites are important factors for controlling kink-band formation.The obtained results show a possibility to open the new door for the development of novel high-strength structural material using the kink bands.展开更多
Hexagonal boron nitride （h-BN） is an important structural material with layered microstructure.Because of the plastic anisotropy,this material shows obvious mechanical hysteresis （nonlinear elastic deformation）.Th...Hexagonal boron nitride （h-BN） is an important structural material with layered microstructure.Because of the plastic anisotropy,this material shows obvious mechanical hysteresis （nonlinear elastic deformation）.There are hysteretic loops at the cyclical load-unload stress-strain curves of h-BN.Consequently,two hot-pressed h-BN cylinders with different textures were studied.The mechanical hysteresis is heavily texture-dependent.The area of hysteretic loop is linearly related with the square of loading stress-level.Two minor loops attached on the hysteretic loops with the same extreme stresses have congruent shapes.It can be concluded that the mechanical hysteresis of h-BN can be explained by a Kink Nonlinear Elastic model developed from the study of a ternary carbide Ti3SiC2.展开更多
基金The project supported by the National Natural Science Foundation of China
文摘Surface originated kink bands consist of an important failure mode for fibre-reinforced compo- sites under compression. The mechanical behavior of the fibre bridging kink bands is explored herein in the context of the post-microbuckling theory. Expressions of bridging force are obtained for the entire postbuckling process of the fibres exhibiting weak or strong hardening. The postbuckling formulation of the fibres is applied to yield the toughness increment due to the advancing kink bands, and consequently leads to a quantitative pre- diction on the overall compressive stress strain curves of the fibre-reinforced composites.
文摘This paper suggests the asymmetric-plastic theory of crystalline solids concerning the plastic rotation of crystal. The deformation of crystalline solids undergoes three microprocesses, lattice distortion, slip over active crystallographic planes and the rotation- of the crystal. In the asymmetric-plastic theory of crystal suggested, the corotational rates of symmetric Cauchy stress and moment stress correspond to the rates of elastic strain and the gradient of the rotational rate of the crystal respectively. The Schmid yield condition and Prager's consistency condition incorporating antisymmetric stress are formulated. Then the asymmetric-plastic model of crystalline solids is applied for the investigation of the onset of kink band by a standard stability analysis. The orientation of the kink band is perpendicular to the primary slip system. The width of the kink band is the function of the ''characteristic length'' of the microstructure of metal materials.
基金supported by Japan Society for the Promotion of Science (JSPS) KAKENHI for Scientific Research on Innovative Areas "MFS Materials Science" (Grant Numbers: JP18H05478 and JP18H05475)partly supported by the Light Metals Educational Foundation of Japan。
文摘For the development of high-strength Mg alloys,active use of Laves phases such as C14-type Mg_(2)Yb and Mg_(2)Ca is strongly expected.However,the brittleness of the Laves phases is the biggest obstacle to it.We first found that kink-band formation can be induced in directionally solidified Mg/Mg_(2)Yb and Mg/Mg_(2)Ca eutectic lamellar alloys when a stress is applied parallel to the lamellar interface,leading to a high yield stress accompanied with ductility.That is,microstructural control can induce a new deformation mode that is not activated in the constituent phases,thereby inducing ductility.It was clarified that the geometric relationship between the operative slip plane in the constituent phases and the lamellar interface,and the microstructural features that provide kink-band nucleation sites are important factors for controlling kink-band formation.The obtained results show a possibility to open the new door for the development of novel high-strength structural material using the kink bands.
基金Funded by National Natural Science Foundation of China(No.10947105)Natural Science Research Project of Education Department of Henan Province (No.2010B430016)
文摘Hexagonal boron nitride （h-BN） is an important structural material with layered microstructure.Because of the plastic anisotropy,this material shows obvious mechanical hysteresis （nonlinear elastic deformation）.There are hysteretic loops at the cyclical load-unload stress-strain curves of h-BN.Consequently,two hot-pressed h-BN cylinders with different textures were studied.The mechanical hysteresis is heavily texture-dependent.The area of hysteretic loop is linearly related with the square of loading stress-level.Two minor loops attached on the hysteretic loops with the same extreme stresses have congruent shapes.It can be concluded that the mechanical hysteresis of h-BN can be explained by a Kink Nonlinear Elastic model developed from the study of a ternary carbide Ti3SiC2.
