Traditional soil additives like Portland cement and lime are prone to cause the brittle fracture behavior of soil,and possibly,environmental impacts.This study explores the potential use of polyurethane organic polyme...Traditional soil additives like Portland cement and lime are prone to cause the brittle fracture behavior of soil,and possibly,environmental impacts.This study explores the potential use of polyurethane organic polymer and sisal fiber in improving the mechanical performance of sand.The effects of polymer content,fiber content,and dry density on the unconfined compressive strength(UCS)and direct tensile strength(DTS)of the polymer-fiber-sand composite were evaluated.The results showed significant increase in UCS and DTS of the reinforced sand with the increase of polymer content,fiber content,and dry density.At high dry density condition,a single peaked stress−strain curve is often observed.Higher polymer content is beneficial to increasing the peak stress,while higher fiber content contributes more to the post-peak stress.The combined use of polymers and fibers in soil reinforcement effectively prevents the propagation and development of cracks under the stress.Scanning electron microscopy(SEM)test was also performed to investigate the micro-structural changes and inter-particle relations.It was found through SEM images that the surface coating,bonding,and filling effects conferred by polymer matrix greatly enhance the interfacial interactions,and hence provide a cohesive environment where the strength of fibers could be readily mobilized.展开更多
Ballistic impact induces complex stress states on fiber-based armor systems.During impact fibers undergo multiaxial loading which includes axial tension,axial compression,transverse compression,and transverse shear.Tr...Ballistic impact induces complex stress states on fiber-based armor systems.During impact fibers undergo multiaxial loading which includes axial tension,axial compression,transverse compression,and transverse shear.Transverse co mpression induced by the projectile leads to permanent defo rmation and fibrillation of fibers resulting in degradation of material tensile strength.Previous work(Sockalingam et al.Textile Res.J 2018) has shown a reduction of 20% in the tensile strength of Dyneema~? SK76 single fibers subjectet to 77% nominal transverse compressive strains.Experimental investigation of quasistatic transverse compression on Dyneema~? SK-76 yarns,unconstrained in the lateral direction,indicate an average of 4% reduction in tensile strength of yarns compressed to 77% nominal strains.In this work we use finite element modeling techniques to understand the difference in residual tensile strength between single fibers and yarns observed in laterally unconstrained transverse compression experiments.Finite element study of the transverse compression response of single fibers and yarns indicate that local strains developed in fibers within the yarn are much lower than the local strains developed in single fibers subjected to a given nominal strain and may explain the less reduction in strength observed in yarns.展开更多
Through adding different additional water use,the compressive strength,splitting tensile strength and fluidity of recycled concrete of three aggregate combination forms were studied by experiment respectively.The expe...Through adding different additional water use,the compressive strength,splitting tensile strength and fluidity of recycled concrete of three aggregate combination forms were studied by experiment respectively.The experimental results show that with the increase of adding additional water use,the compressive strength and splitting tensile strength of recycled coarse aggregate concrete decrease,but that of recycled fine aggregate concrete and recycled all aggregate concrete increase firstly then decrease.When additional water use is added more 15% or 20% than that of basic ordinary concrete,the recycled coarse aggregate concrete and fine one can get pretty good fluidity.When it is added more 30%,the recycled all aggregate concrete has fluidity that is just satisfied.展开更多
The concepts of rock strength intervals are presented in this work, furthermore, central values of intervals and their corresponding credibility are provided using two-case study based on blind data theory and fuzzy i...The concepts of rock strength intervals are presented in this work, furthermore, central values of intervals and their corresponding credibility are provided using two-case study based on blind data theory and fuzzy interval estimation. 60 granite specimens are first tested, the compressive strength interval and tensile strength interval are [ 103.68, 219.6 l ] and [7.53, 11,86] MPa, while the tested mean values of compressive strength and tensile strength are 152.86 and 10.14 MPa, the credibilities are less than 58.4% and around 70.4%, respectively, the credibility of shear strength is between 40% and 60%. Then 70 other rock specimens are designed and tested, the similar conclusions can be reached. The results show that the conventional definite values are the particular values within the intervals, and the credibility of them often fails to reach the high-precision engineering requirement. The results demonstrate the feasibility and application potential of this proposed algorithm for the engineering practice. The references for engineering value selection of rock strength under different credibility or according to frequency distribution of central values are provided to increase the reliability and precision of calculation.展开更多
The tensile strength,compressive strength and electrical resistivity of TiB2/C composite cathode coating were measured with a hydraulic pressure universal test machine and an electrical resistivity test device,and the...The tensile strength,compressive strength and electrical resistivity of TiB2/C composite cathode coating were measured with a hydraulic pressure universal test machine and an electrical resistivity test device,and the effects of carbon fibre content and carbon fibre length on tensile strength,compressive strength and electrical resistivity were investigated.The results show that the tensile strength of coating increases at the beginning and then reduces with the increase of carbon fibre content when the carbon fibre(length of 3 mm)content ranges from 0 to 4.0%;at the carbon fibre content of 1.5%,the tensile strength of coating reaches the maximum,25.6 MPa.For the coating with carbon fibre content of 1.5%,the carbon fibre length has a great influence on tensile strength and compressive strength of coating;when the carbon fibre length is 6 mm,the tensile strength and compressive strength of coating reach the maximum,27.6 MPa and 39.2 MPa,respectively.The electrical resistivity of coating reduces with the rise of temperature and the length of carbon fibre,and the influence of carbon fibre length on electrical resistivity of coating at low temperature(30-200℃)is more obvious than that at high temperature(960℃).展开更多
基金Project(41877212)supported by the National Natural Science Foundation of ChinaProject(2017010)supported by the Water Conservancy Science and Technology Project of Jiangsu Province,ChinaProject(B200202013)supported by the Fundamental Research Funds for the Central Universities,China。
文摘Traditional soil additives like Portland cement and lime are prone to cause the brittle fracture behavior of soil,and possibly,environmental impacts.This study explores the potential use of polyurethane organic polymer and sisal fiber in improving the mechanical performance of sand.The effects of polymer content,fiber content,and dry density on the unconfined compressive strength(UCS)and direct tensile strength(DTS)of the polymer-fiber-sand composite were evaluated.The results showed significant increase in UCS and DTS of the reinforced sand with the increase of polymer content,fiber content,and dry density.At high dry density condition,a single peaked stress−strain curve is often observed.Higher polymer content is beneficial to increasing the peak stress,while higher fiber content contributes more to the post-peak stress.The combined use of polymers and fibers in soil reinforcement effectively prevents the propagation and development of cracks under the stress.Scanning electron microscopy(SEM)test was also performed to investigate the micro-structural changes and inter-particle relations.It was found through SEM images that the surface coating,bonding,and filling effects conferred by polymer matrix greatly enhance the interfacial interactions,and hence provide a cohesive environment where the strength of fibers could be readily mobilized.
基金the startup funding provided by the University of South Carolina。
文摘Ballistic impact induces complex stress states on fiber-based armor systems.During impact fibers undergo multiaxial loading which includes axial tension,axial compression,transverse compression,and transverse shear.Transverse co mpression induced by the projectile leads to permanent defo rmation and fibrillation of fibers resulting in degradation of material tensile strength.Previous work(Sockalingam et al.Textile Res.J 2018) has shown a reduction of 20% in the tensile strength of Dyneema~? SK76 single fibers subjectet to 77% nominal transverse compressive strains.Experimental investigation of quasistatic transverse compression on Dyneema~? SK-76 yarns,unconstrained in the lateral direction,indicate an average of 4% reduction in tensile strength of yarns compressed to 77% nominal strains.In this work we use finite element modeling techniques to understand the difference in residual tensile strength between single fibers and yarns observed in laterally unconstrained transverse compression experiments.Finite element study of the transverse compression response of single fibers and yarns indicate that local strains developed in fibers within the yarn are much lower than the local strains developed in single fibers subjected to a given nominal strain and may explain the less reduction in strength observed in yarns.
基金Project(Xiangjianke(2007)No.425) supported by Scientific Research Fund of Hunan Provincial Construction DepartmentProject supported by the Youth Framework Teacher Fund of Xiangtan University(2006)
文摘Through adding different additional water use,the compressive strength,splitting tensile strength and fluidity of recycled concrete of three aggregate combination forms were studied by experiment respectively.The experimental results show that with the increase of adding additional water use,the compressive strength and splitting tensile strength of recycled coarse aggregate concrete decrease,but that of recycled fine aggregate concrete and recycled all aggregate concrete increase firstly then decrease.When additional water use is added more 15% or 20% than that of basic ordinary concrete,the recycled coarse aggregate concrete and fine one can get pretty good fluidity.When it is added more 30%,the recycled all aggregate concrete has fluidity that is just satisfied.
基金Project(2011DA105287-MS201605)supported by the State Key Laboratory of Coal Mine Disaster Dynamics and Control,ChinaProject(51374242)supported by the National Natural Science Foundation of ChinaProject(106112016CDJXY240004)supported by the Fundamental Research Funds for the Central Universities,China
文摘The concepts of rock strength intervals are presented in this work, furthermore, central values of intervals and their corresponding credibility are provided using two-case study based on blind data theory and fuzzy interval estimation. 60 granite specimens are first tested, the compressive strength interval and tensile strength interval are [ 103.68, 219.6 l ] and [7.53, 11,86] MPa, while the tested mean values of compressive strength and tensile strength are 152.86 and 10.14 MPa, the credibilities are less than 58.4% and around 70.4%, respectively, the credibility of shear strength is between 40% and 60%. Then 70 other rock specimens are designed and tested, the similar conclusions can be reached. The results show that the conventional definite values are the particular values within the intervals, and the credibility of them often fails to reach the high-precision engineering requirement. The results demonstrate the feasibility and application potential of this proposed algorithm for the engineering practice. The references for engineering value selection of rock strength under different credibility or according to frequency distribution of central values are provided to increase the reliability and precision of calculation.
基金Project(2005CB623703)supported by the Major State Basic Research Development Program of China
文摘The tensile strength,compressive strength and electrical resistivity of TiB2/C composite cathode coating were measured with a hydraulic pressure universal test machine and an electrical resistivity test device,and the effects of carbon fibre content and carbon fibre length on tensile strength,compressive strength and electrical resistivity were investigated.The results show that the tensile strength of coating increases at the beginning and then reduces with the increase of carbon fibre content when the carbon fibre(length of 3 mm)content ranges from 0 to 4.0%;at the carbon fibre content of 1.5%,the tensile strength of coating reaches the maximum,25.6 MPa.For the coating with carbon fibre content of 1.5%,the carbon fibre length has a great influence on tensile strength and compressive strength of coating;when the carbon fibre length is 6 mm,the tensile strength and compressive strength of coating reach the maximum,27.6 MPa and 39.2 MPa,respectively.The electrical resistivity of coating reduces with the rise of temperature and the length of carbon fibre,and the influence of carbon fibre length on electrical resistivity of coating at low temperature(30-200℃)is more obvious than that at high temperature(960℃).
