Influence of silicon oxide(SiO_2) and aluminum oxide(Al_2O_3) nanoparticles on the stability of nanoparticles and sodium dodecyl sulfate(SDS) mixed solution foams was studied at bulk and bubble-scale. Foam apparent vi...Influence of silicon oxide(SiO_2) and aluminum oxide(Al_2O_3) nanoparticles on the stability of nanoparticles and sodium dodecyl sulfate(SDS) mixed solution foams was studied at bulk and bubble-scale. Foam apparent viscosity was also determined in Hele-Shaw cell In order to investigate the foam performance at static and dynamic conditions. Results show that the maximum adsorption of surfactant on the nanoparticles occurs at 3 wt% surfactant concentration. Foam stability increases while the foamability decreases with the increasing nanoparticle concentration. However, optimum nanoparticle concentration corresponding to maximum foam stability was obtained at 1.0 wt% nanoparticle concentration for the hydrophilic SiO_2/SDS and Al_2O_3/SDS foams. Foam performance was enhanced with increasing nanoparticles hydrophobicity. Air-foams were generally more stable than CO_2 foams.Foam apparent viscosity increased in the presence of nanoparticles from 20.34 mPa·s to 84.84 mPa·s while the film thickness increased from 27.5 μm to 136 μm. This study suggests that the static and dynamic stability of conventional foams could be improved with addition of appropriate concentration of nanoparticles into the surfactant solution. The nanoparticles improve foam stability by their adsorption and aggregation at the foam lamellae to increase film thickness and dilational viscoelasticity. This prevents liquid drainage and film thinning and improves foam stability both at the bulk and bubble scale.展开更多
以直腿半圆形UCC拱架为对象,进行了不同侧压比荷载条件下的全尺寸拱架试验研究,从变形破坏形态、承载力、材料应变等方面进行对比分析,掌握了新型拱架的承载特性和屈服失稳机制。拱架受力初期处于线弹性变形阶段,拱架内力呈显著压弯状态...以直腿半圆形UCC拱架为对象,进行了不同侧压比荷载条件下的全尺寸拱架试验研究,从变形破坏形态、承载力、材料应变等方面进行对比分析,掌握了新型拱架的承载特性和屈服失稳机制。拱架受力初期处于线弹性变形阶段,拱架内力呈显著压弯状态,由于部分截面出现了强度破坏而导致拱架整体屈服,而后随持续加载拱架出现整体结构失稳,进而彻底丧失承载能力。UCC29试验拱架在λ=1.0加载条件下整体屈服承载力为1 230 k N,是相同尺寸U36拱架的1.56倍。拱架屈服承载力随侧压比λ(λ≥0.5)呈指数型降低趋势,且拱架变形形态及危险截面位置也受侧压比影响显著。对于直腿半圆形拱架而言,侧压比在一定范围内越小,拱架内力越接近轴压状态,拱架能够承担的荷载也越高。展开更多
基金the Ministry of Higher Education(Vot no.Q.J130000.2542.08H61)Universiti Teknologi(UTM)Malaysia,for supporting this research through research management grant
文摘Influence of silicon oxide(SiO_2) and aluminum oxide(Al_2O_3) nanoparticles on the stability of nanoparticles and sodium dodecyl sulfate(SDS) mixed solution foams was studied at bulk and bubble-scale. Foam apparent viscosity was also determined in Hele-Shaw cell In order to investigate the foam performance at static and dynamic conditions. Results show that the maximum adsorption of surfactant on the nanoparticles occurs at 3 wt% surfactant concentration. Foam stability increases while the foamability decreases with the increasing nanoparticle concentration. However, optimum nanoparticle concentration corresponding to maximum foam stability was obtained at 1.0 wt% nanoparticle concentration for the hydrophilic SiO_2/SDS and Al_2O_3/SDS foams. Foam performance was enhanced with increasing nanoparticles hydrophobicity. Air-foams were generally more stable than CO_2 foams.Foam apparent viscosity increased in the presence of nanoparticles from 20.34 mPa·s to 84.84 mPa·s while the film thickness increased from 27.5 μm to 136 μm. This study suggests that the static and dynamic stability of conventional foams could be improved with addition of appropriate concentration of nanoparticles into the surfactant solution. The nanoparticles improve foam stability by their adsorption and aggregation at the foam lamellae to increase film thickness and dilational viscoelasticity. This prevents liquid drainage and film thinning and improves foam stability both at the bulk and bubble scale.
文摘以直腿半圆形UCC拱架为对象,进行了不同侧压比荷载条件下的全尺寸拱架试验研究,从变形破坏形态、承载力、材料应变等方面进行对比分析,掌握了新型拱架的承载特性和屈服失稳机制。拱架受力初期处于线弹性变形阶段,拱架内力呈显著压弯状态,由于部分截面出现了强度破坏而导致拱架整体屈服,而后随持续加载拱架出现整体结构失稳,进而彻底丧失承载能力。UCC29试验拱架在λ=1.0加载条件下整体屈服承载力为1 230 k N,是相同尺寸U36拱架的1.56倍。拱架屈服承载力随侧压比λ(λ≥0.5)呈指数型降低趋势,且拱架变形形态及危险截面位置也受侧压比影响显著。对于直腿半圆形拱架而言,侧压比在一定范围内越小,拱架内力越接近轴压状态,拱架能够承担的荷载也越高。
