The effects of cell wall property on the compressive performance of high porosity, closed-cell aluminum foams prepared by gas injection method were investigated. The research was conducted both experimentally and nume...The effects of cell wall property on the compressive performance of high porosity, closed-cell aluminum foams prepared by gas injection method were investigated. The research was conducted both experimentally and numerically. Foam specimens prepared from conditioned melt were tested under uniaxial compressive loading condition. The cell wall microstructure and fracture were observed through optical microscope（OM） and scanning electron microscope（SEM）, which indicates that the cell wall property is impaired by the defects in cell walls and oxide films on the cell wall surface. Subsequently, finite element（FE） models based on three-dimensional thin shell Kelvin tetrakaidecahedron were developed based on the mechanical properties of the raw material and solid material that are determined by using experimental measurements. The simulation results show that the plateau stress of the nominal stress-strain curve exhibits a linear relationship with the yield strength of the cell wall material. The simulation plateau stress is higher than the experimental data, partly owing to the substitution of solid material for cell wall material in the process of the establishment of FE models.展开更多
To study the behavior and design of tubed circular steel reinforced concrete (TCSRC) short column under axial compressive loads, a nonlinear finite element model (FEM) has been developed to simulate this kind of struc...To study the behavior and design of tubed circular steel reinforced concrete (TCSRC) short column under axial compressive loads, a nonlinear finite element model (FEM) has been developed to simulate this kind of structure. Depending on the FEM results, an elastic-plastic analysis was carried out to clarify the status of steel tube, then a simplified procedure was proposed to predict the compressive axial load strength. The results obtained from this procedure were compared with the test results. It is found that they agree well each other.展开更多
It is well known that the finer particle of cementing material has more pozzolanic reaction than the coarser. This paper investigates the shear properties of geocomposite soil with various particle sizes of bottom ash...It is well known that the finer particle of cementing material has more pozzolanic reaction than the coarser. This paper investigates the shear properties of geocomposite soil with various particle sizes of bottom ash. The geocomposite soil （GCS） in this study consists of dredged soil, bottom ash and cement for recycling dredged soil and bottom ash. Three different particle sizes of bottom ash passing No. 4 sieve, No. 40 sieve, and No. 140 sieve were added into soil mixtures, namely as GCS 4, GCS 40, and GCS 140, respectively. These bottom ashes have the same chemical component except for different particle sizes. Several mixtures were prepared with various contents of bottom ash ranging from 0 to 100% at 50% intervals by the weight of dry dredged soil. In this study, several series of unconfined compression test were carried out on the mixtures with various curing times. It is found that the unconfined compressive strength is a function of curing time and bottom ash content. For the curing time less than 28 days, the GCS 4 has higher unconfined compressive strength than the GCS 40 and GCS 140 due to the interlocking effect and friction between the particles with angular shape of coarse bottom ash. For the curing time larger than 28 days, the GCS 140 has higher strength due to the pozzolanic reaction. However, the ratios of secant modulus to unconfined compressive strength of three mixtures are almost the same, and in range of （46-100）, regardless of mixing condition and curing time.展开更多
基金Project(2013DFR50330)supported by the International Cooperation Project of Science and Technology Ministry of China
文摘The effects of cell wall property on the compressive performance of high porosity, closed-cell aluminum foams prepared by gas injection method were investigated. The research was conducted both experimentally and numerically. Foam specimens prepared from conditioned melt were tested under uniaxial compressive loading condition. The cell wall microstructure and fracture were observed through optical microscope（OM） and scanning electron microscope（SEM）, which indicates that the cell wall property is impaired by the defects in cell walls and oxide films on the cell wall surface. Subsequently, finite element（FE） models based on three-dimensional thin shell Kelvin tetrakaidecahedron were developed based on the mechanical properties of the raw material and solid material that are determined by using experimental measurements. The simulation results show that the plateau stress of the nominal stress-strain curve exhibits a linear relationship with the yield strength of the cell wall material. The simulation plateau stress is higher than the experimental data, partly owing to the substitution of solid material for cell wall material in the process of the establishment of FE models.
基金Sponsored by the National Natural Science Foundation of China (Grant No.50708027)National Key Technology R&D Program of China(Grant No.2006BAJ01B02)
文摘To study the behavior and design of tubed circular steel reinforced concrete (TCSRC) short column under axial compressive loads, a nonlinear finite element model (FEM) has been developed to simulate this kind of structure. Depending on the FEM results, an elastic-plastic analysis was carried out to clarify the status of steel tube, then a simplified procedure was proposed to predict the compressive axial load strength. The results obtained from this procedure were compared with the test results. It is found that they agree well each other.
文摘It is well known that the finer particle of cementing material has more pozzolanic reaction than the coarser. This paper investigates the shear properties of geocomposite soil with various particle sizes of bottom ash. The geocomposite soil （GCS） in this study consists of dredged soil, bottom ash and cement for recycling dredged soil and bottom ash. Three different particle sizes of bottom ash passing No. 4 sieve, No. 40 sieve, and No. 140 sieve were added into soil mixtures, namely as GCS 4, GCS 40, and GCS 140, respectively. These bottom ashes have the same chemical component except for different particle sizes. Several mixtures were prepared with various contents of bottom ash ranging from 0 to 100% at 50% intervals by the weight of dry dredged soil. In this study, several series of unconfined compression test were carried out on the mixtures with various curing times. It is found that the unconfined compressive strength is a function of curing time and bottom ash content. For the curing time less than 28 days, the GCS 4 has higher unconfined compressive strength than the GCS 40 and GCS 140 due to the interlocking effect and friction between the particles with angular shape of coarse bottom ash. For the curing time larger than 28 days, the GCS 140 has higher strength due to the pozzolanic reaction. However, the ratios of secant modulus to unconfined compressive strength of three mixtures are almost the same, and in range of （46-100）, regardless of mixing condition and curing time.
