In the impact tests of soft materials, we sometimes observe a thorn shape in the rising segment of the impact force waveform. However, the reason for the occurrence of the thorn shape has not been made clear. In this ...In the impact tests of soft materials, we sometimes observe a thorn shape in the rising segment of the impact force waveform. However, the reason for the occurrence of the thorn shape has not been made clear. In this study, thorn-shape waveforms of several soft materials are measured using compact drop test equipment under the condition of a flat frontal impact. A flat frontal impact is the condition where a drop hammer with a flat bottom surface strikes a plate-like soft material in the normal direction. Synchronized impact forces are measured using two sensors installed on both the drop hammer side and the floor side. The examined soft materials are a sponge sheet, sponge rubber sheet, gel sheet, rubber sheet, flat oil clay, low-rebound urethane foam, cork sheet, sliced ham, pork ham steak, and pork. Based on the test results, the features of the thorn-shape waveforms are discussed from a bird’s-eye view. Furthermore, the occurrence mechanism of the thorn-shape waveforms is discussed from the viewpoint of viscosity discontinuity and the double-strike phenomenon.展开更多
基于室内桩孔水泥土夯击试验,研究夯锤形状、夯锤落距和夯击次数对挤密力和压实系数的影响规律,建立拟合数学模型。研究结果表明:平底锤对桩底的挤密力最大,锥底锤对桩侧的挤密力最大。挤密力和桩体压实系数与夯击次数、夯锤落距之间存...基于室内桩孔水泥土夯击试验,研究夯锤形状、夯锤落距和夯击次数对挤密力和压实系数的影响规律,建立拟合数学模型。研究结果表明:平底锤对桩底的挤密力最大,锥底锤对桩侧的挤密力最大。挤密力和桩体压实系数与夯击次数、夯锤落距之间存在对数函数相关性,用对数数学模型计算挤密力平均误差不超过7 k Pa,压实系数平均误差不超过2%;根据桩体压实系数的数学模型和挤密力随夯击次数的规律,以夯击能作为考量标准,提出最优夯击方案为锤底为锥形、30 cm落距和每层夯击30次。展开更多
To achieve well defined amphiphilic C 60 containing macromolecules,C 60 conjugated polystyrene(C 60 PS)was first synthesized via tandem atom transfer radical polymerization(ATRP).With the help of tetrabutylammonium br...To achieve well defined amphiphilic C 60 containing macromolecules,C 60 conjugated polystyrene(C 60 PS)was first synthesized via tandem atom transfer radical polymerization(ATRP).With the help of tetrabutylammonium bromide(TBAB),taurine(2 aminoethanesulfonic acid) can be carried from water phase into the phenyl chloride phase and then react with C 60 PS.The final product——taurine modified C 60 conjugated polystyrene—is a novel type of highly asymmetric amphiphilic diblock copolymers,which can form spherical crew cut type micelles by adding water in small amounts into its tetrahydrofuran solution.UV vis spectroscopy and trasmission electronic microscopy have been employed to monitor the aggregating process of these spherical micelles and observe their final morphology respectively.展开更多
Atom transfer radical polymerization of protected 2 hydroxyethyl acrylate (HEA\|TMS) was conducted to prepare well\|defined bromo\|terminated macroinitiators,which were further allowed to react with large excess amoun...Atom transfer radical polymerization of protected 2 hydroxyethyl acrylate (HEA\|TMS) was conducted to prepare well\|defined bromo\|terminated macroinitiators,which were further allowed to react with large excess amount of C 60 under ATRP condition.A well defined hammer shaped C 60 PHEA was then obtained by hydrolysis of C 60 PHEA TMS under mild conditions.A TEM observation of the association behavior of these well defined hammer like C 60 PHEA macromolecules showed that they assemble into spherical vesicles in water.Their characteristic inner water phase was further confirmed by fluorescence probe method.Also,it was found that the size of vesicles decreased as the increase of molecular weight of PHEA.展开更多
文摘In the impact tests of soft materials, we sometimes observe a thorn shape in the rising segment of the impact force waveform. However, the reason for the occurrence of the thorn shape has not been made clear. In this study, thorn-shape waveforms of several soft materials are measured using compact drop test equipment under the condition of a flat frontal impact. A flat frontal impact is the condition where a drop hammer with a flat bottom surface strikes a plate-like soft material in the normal direction. Synchronized impact forces are measured using two sensors installed on both the drop hammer side and the floor side. The examined soft materials are a sponge sheet, sponge rubber sheet, gel sheet, rubber sheet, flat oil clay, low-rebound urethane foam, cork sheet, sliced ham, pork ham steak, and pork. Based on the test results, the features of the thorn-shape waveforms are discussed from a bird’s-eye view. Furthermore, the occurrence mechanism of the thorn-shape waveforms is discussed from the viewpoint of viscosity discontinuity and the double-strike phenomenon.
文摘基于室内桩孔水泥土夯击试验,研究夯锤形状、夯锤落距和夯击次数对挤密力和压实系数的影响规律,建立拟合数学模型。研究结果表明:平底锤对桩底的挤密力最大,锥底锤对桩侧的挤密力最大。挤密力和桩体压实系数与夯击次数、夯锤落距之间存在对数函数相关性,用对数数学模型计算挤密力平均误差不超过7 k Pa,压实系数平均误差不超过2%;根据桩体压实系数的数学模型和挤密力随夯击次数的规律,以夯击能作为考量标准,提出最优夯击方案为锤底为锥形、30 cm落距和每层夯击30次。
文摘To achieve well defined amphiphilic C 60 containing macromolecules,C 60 conjugated polystyrene(C 60 PS)was first synthesized via tandem atom transfer radical polymerization(ATRP).With the help of tetrabutylammonium bromide(TBAB),taurine(2 aminoethanesulfonic acid) can be carried from water phase into the phenyl chloride phase and then react with C 60 PS.The final product——taurine modified C 60 conjugated polystyrene—is a novel type of highly asymmetric amphiphilic diblock copolymers,which can form spherical crew cut type micelles by adding water in small amounts into its tetrahydrofuran solution.UV vis spectroscopy and trasmission electronic microscopy have been employed to monitor the aggregating process of these spherical micelles and observe their final morphology respectively.
文摘Atom transfer radical polymerization of protected 2 hydroxyethyl acrylate (HEA\|TMS) was conducted to prepare well\|defined bromo\|terminated macroinitiators,which were further allowed to react with large excess amount of C 60 under ATRP condition.A well defined hammer shaped C 60 PHEA was then obtained by hydrolysis of C 60 PHEA TMS under mild conditions.A TEM observation of the association behavior of these well defined hammer like C 60 PHEA macromolecules showed that they assemble into spherical vesicles in water.Their characteristic inner water phase was further confirmed by fluorescence probe method.Also,it was found that the size of vesicles decreased as the increase of molecular weight of PHEA.
