The experiments related to stress states of ferrite and cementite in carbon steels were carried out including in situ four-point bending and tensile test by X-ray diffraction technique. Stresses in the cementite phase...The experiments related to stress states of ferrite and cementite in carbon steels were carried out including in situ four-point bending and tensile test by X-ray diffraction technique. Stresses in the cementite phase can be measured by conventional X-ray diffraction instrument after a specific treatment on the specimen surface. In order to estimate the stress states in two phases, the X-ray elastic constants of two phases in single-phase state （PXEC） are determined by the experimental X-ray elastic constants of them in composite state （CXEC）. The effects of volume fraction and particle size of spheroidal cementite on the interphase stress state are estimated. The experimental results are in good agreement with the theoretical relationships reported in the previous studies.展开更多
In this work,a multi-phase Zr-30Ti-7Nb-4Sn alloy with large near-linear elastic deformability was prepared by the solution treatment plus pre-straining(S TP)treatment,and the underlying mechanism accountable for the n...In this work,a multi-phase Zr-30Ti-7Nb-4Sn alloy with large near-linear elastic deformability was prepared by the solution treatment plus pre-straining(S TP)treatment,and the underlying mechanism accountable for the near-linear elastic deformation was systematically clarified.It was found that the Zr-30Ti-7Nb-4Sn alloy was composed ofβ,α″andα′phases,and numerous dislocations were formed in the alloy specimen after STP treatment.With the retarding effect of high-density dislocations,the stress-induced martensitic(SIM)transformation fromβtoα″phases took place homogeneously and continuously during loading,in conjunction with the occurrence of elastic deformation ofβ,α″andα′phases.Under the entire tensile procedure,no observable phase transformation occurred betweenα′martensite andβphase.Consequently,the near-linear elastic deformation capability in STP Zr-30Ti-7Nb-4Sn alloy is mainly ascribed to the coupling actions of consecutiveβ→α″SIM transformation and intrinsic elastic deformation ofβ,α″andα′phases.These experimental results provide a basis for designing and developing novel multi-phase Zr-based alloys that possess large near-linear deformability.展开更多
在胶凝原油水力悬浮输送过程中,胶凝原油颗粒在复杂的相间作用力下发生变形。本文基于VOSET方法对胶凝原油颗粒在水力悬浮输送过程中的变形进行模拟研究,颗粒变形后的长短轴通过Image Pro Plus图像处理软件确定,变形的大小用变形度衡量...在胶凝原油水力悬浮输送过程中,胶凝原油颗粒在复杂的相间作用力下发生变形。本文基于VOSET方法对胶凝原油颗粒在水力悬浮输送过程中的变形进行模拟研究,颗粒变形后的长短轴通过Image Pro Plus图像处理软件确定,变形的大小用变形度衡量。模拟结果表明,在水流的剪切作用下圆形的颗粒逐渐发生变形,变形后的原油颗粒接近椭圆形。在给定的模拟条件下,当温度分别为55℃(原油属于牛顿流体)、46℃(原油属于假塑性流体)、40℃(屈服假塑性流体,并呈现胶凝状态)时,原油颗粒的出口变形度分别为59.38%、47.29%、32.47%,胶凝原油颗粒的变形度最小。通过机理分析,明确了胶凝原油颗粒变形受流场的剪切作用、原油的屈服值和剪切稀释性共同影响。展开更多
To determine the time-independent constitutive modeling for porous and multi- phase nanocrystalline materials and understand the effects of grain size and porosity on their mechanical behavior, each phase was treated ...To determine the time-independent constitutive modeling for porous and multi- phase nanocrystalline materials and understand the effects of grain size and porosity on their mechanical behavior, each phase was treated as a mixture of grain interior and grain bound- ary, and pores were taken as a single phase, then Budiansky＇s self-consistent method was used to calculate the Young＇s modulus of porous, possible multi-phase, nanocrystalline materials, the prediction being in good agreement with the results in the literature. Further, the established method is extended to simulate the constitutive relations of porous and possible multi-phase nanocrystalline materials with small plastic deformation in conjunction with the secant-moduli approach and iso-strain assumption. Comparisons between the experimental grain size and porosity dependent mechanical data and the corresponding predictions using the established model show that it appears to be capable of describing the time-independent mechanical behaviors for porous and multi-phase nanocrystalline materials in a small plastic strain range. Further discussion on the modification factor, the advantages and limitations of the model developed were present.展开更多
Since the jets and detonation gaseous products are separated by sharp interfaces, the traditional smoothed particle hydrodynamics (SPH) method is difficult to avoid the computational instability at interfaces. The mul...Since the jets and detonation gaseous products are separated by sharp interfaces, the traditional smoothed particle hydrodynamics (SPH) method is difficult to avoid the computational instability at interfaces. The multi-phase SPH (MSPH) method was applied to improving the stabil-ity, which smoothes the particle density and makes pressure continuous at interfaces. Numericalexamples of jet forming process were used to test capability of the MSPH method. The results show that the method remains algorithm stability for large density gradient between the jets and gaseous products and has potential application to both the explosion and the jet problems. The effect of initiation ways of the shaped charge was discussed as well.展开更多
In this paper, a finite element method （FEM）-based multi-phase problem based on a newly proposed thermal elastoplastic constitutive model for saturated/unsaturated geomaterial is discussed. A program of FEM named as...In this paper, a finite element method （FEM）-based multi-phase problem based on a newly proposed thermal elastoplastic constitutive model for saturated/unsaturated geomaterial is discussed. A program of FEM named as SOFT, adopting unified field equations for thermo-hydro-mechanical-air （THMA） behavior of geomaterial and using finite element-finite difference （FE-FD） scheme for so/l-water-air three-phase coupling problem, is used in the numerical simulation. As an application of the newly proposed numerical method, two engineering problems, one for slope failure in unsaturated model ground and another for in situ heating test related to deep geological repository of high-level radioactive waste （HLRW）, are simulated. The model tests on slope failure in unsaturated Shirasu ground, carried out by Kitamura et al. （2007）, is simulated in the framework of soil-water-air three-phase coupling under the condition of constant temperature. While the in situ heating test reported by Munoz （2006） is simulated in the same framework under the conditions of variable temperature hut constant air pressure.展开更多
文摘The experiments related to stress states of ferrite and cementite in carbon steels were carried out including in situ four-point bending and tensile test by X-ray diffraction technique. Stresses in the cementite phase can be measured by conventional X-ray diffraction instrument after a specific treatment on the specimen surface. In order to estimate the stress states in two phases, the X-ray elastic constants of two phases in single-phase state （PXEC） are determined by the experimental X-ray elastic constants of them in composite state （CXEC）. The effects of volume fraction and particle size of spheroidal cementite on the interphase stress state are estimated. The experimental results are in good agreement with the theoretical relationships reported in the previous studies.
基金financially supported by the National Natural Science Foundation of China(No.52175410)the Six Talent Peaks Project in Jiangsu Province(No.2019-XCL-113)+1 种基金Zhenjiang Science&Technology Program(No.GY2020001)the Project of Faculty of Agricultural Equipment of Jiangsu University(No.NZXB20200101)。
文摘In this work,a multi-phase Zr-30Ti-7Nb-4Sn alloy with large near-linear elastic deformability was prepared by the solution treatment plus pre-straining(S TP)treatment,and the underlying mechanism accountable for the near-linear elastic deformation was systematically clarified.It was found that the Zr-30Ti-7Nb-4Sn alloy was composed ofβ,α″andα′phases,and numerous dislocations were formed in the alloy specimen after STP treatment.With the retarding effect of high-density dislocations,the stress-induced martensitic(SIM)transformation fromβtoα″phases took place homogeneously and continuously during loading,in conjunction with the occurrence of elastic deformation ofβ,α″andα′phases.Under the entire tensile procedure,no observable phase transformation occurred betweenα′martensite andβphase.Consequently,the near-linear elastic deformation capability in STP Zr-30Ti-7Nb-4Sn alloy is mainly ascribed to the coupling actions of consecutiveβ→α″SIM transformation and intrinsic elastic deformation ofβ,α″andα′phases.These experimental results provide a basis for designing and developing novel multi-phase Zr-based alloys that possess large near-linear deformability.
文摘在胶凝原油水力悬浮输送过程中,胶凝原油颗粒在复杂的相间作用力下发生变形。本文基于VOSET方法对胶凝原油颗粒在水力悬浮输送过程中的变形进行模拟研究,颗粒变形后的长短轴通过Image Pro Plus图像处理软件确定,变形的大小用变形度衡量。模拟结果表明,在水流的剪切作用下圆形的颗粒逐渐发生变形,变形后的原油颗粒接近椭圆形。在给定的模拟条件下,当温度分别为55℃(原油属于牛顿流体)、46℃(原油属于假塑性流体)、40℃(屈服假塑性流体,并呈现胶凝状态)时,原油颗粒的出口变形度分别为59.38%、47.29%、32.47%,胶凝原油颗粒的变形度最小。通过机理分析,明确了胶凝原油颗粒变形受流场的剪切作用、原油的屈服值和剪切稀释性共同影响。
基金Project supported by the National Natural Science Foundation of China (No. 10502025)Fok Ying Tong Education Foundation (No.101005)University Foundation of Jiangsu Province (No.05KJB1300421)
文摘To determine the time-independent constitutive modeling for porous and multi- phase nanocrystalline materials and understand the effects of grain size and porosity on their mechanical behavior, each phase was treated as a mixture of grain interior and grain bound- ary, and pores were taken as a single phase, then Budiansky＇s self-consistent method was used to calculate the Young＇s modulus of porous, possible multi-phase, nanocrystalline materials, the prediction being in good agreement with the results in the literature. Further, the established method is extended to simulate the constitutive relations of porous and possible multi-phase nanocrystalline materials with small plastic deformation in conjunction with the secant-moduli approach and iso-strain assumption. Comparisons between the experimental grain size and porosity dependent mechanical data and the corresponding predictions using the established model show that it appears to be capable of describing the time-independent mechanical behaviors for porous and multi-phase nanocrystalline materials in a small plastic strain range. Further discussion on the modification factor, the advantages and limitations of the model developed were present.
基金Supported by New Century Exellent Talents in University(NCET) in China for National "973"Program in China (No.61338)Innvoative Research Project of Xi’an Hi-Tech Institute(No.EPXY0806)
文摘Since the jets and detonation gaseous products are separated by sharp interfaces, the traditional smoothed particle hydrodynamics (SPH) method is difficult to avoid the computational instability at interfaces. The multi-phase SPH (MSPH) method was applied to improving the stabil-ity, which smoothes the particle density and makes pressure continuous at interfaces. Numericalexamples of jet forming process were used to test capability of the MSPH method. The results show that the method remains algorithm stability for large density gradient between the jets and gaseous products and has potential application to both the explosion and the jet problems. The effect of initiation ways of the shaped charge was discussed as well.
文摘In this paper, a finite element method （FEM）-based multi-phase problem based on a newly proposed thermal elastoplastic constitutive model for saturated/unsaturated geomaterial is discussed. A program of FEM named as SOFT, adopting unified field equations for thermo-hydro-mechanical-air （THMA） behavior of geomaterial and using finite element-finite difference （FE-FD） scheme for so/l-water-air three-phase coupling problem, is used in the numerical simulation. As an application of the newly proposed numerical method, two engineering problems, one for slope failure in unsaturated model ground and another for in situ heating test related to deep geological repository of high-level radioactive waste （HLRW）, are simulated. The model tests on slope failure in unsaturated Shirasu ground, carried out by Kitamura et al. （2007）, is simulated in the framework of soil-water-air three-phase coupling under the condition of constant temperature. While the in situ heating test reported by Munoz （2006） is simulated in the same framework under the conditions of variable temperature hut constant air pressure.
