Sisal filbre is a kind of natural filbre which possesses high specic strength and modu- lus, low price, recycalability, easy availability in some countries. Using sisal filbre as reinforcement to make sisal filbre r...Sisal filbre is a kind of natural filbre which possesses high specic strength and modu- lus, low price, recycalability, easy availability in some countries. Using sisal filbre as reinforcement to make sisal filbre reinforced polymer composites has aroused great interest of materials scientists and engineers all over the world. Many researches have been done in recent years which include the study of mechanical properties of the composites, nding an ecient way to improve the inter- facial bonding properties between sisal bre and polymeric matrices and bre surface treatment on the mechanical performance of the composites. Though many researches on sisal bre reinforced composites have been done so far, none deals with the fracture properties of this novel composite which is crucial for the actual application of this material. In this research, Charpy impact test and compact tension test were employed to study the fracture toughness of sisal bre reinforced vinyl ester and epoxy composites. The eect of bre surface treatment on the fracture properties of these composites by permanganate and silane was evaluated. The initiation and propagation of the crack were observed with optical microscopy (OM). The fracture morphologies revealed by OM explains the fracture phenomenon of sisal bre reinforced composites.展开更多
The nonlinear analysis of pounding between bridge deck segments subjected to multi-support excitations and multi-dimensional earthquake motion was performed.A novel bottom rigid element(BRE)method of the current displ...The nonlinear analysis of pounding between bridge deck segments subjected to multi-support excitations and multi-dimensional earthquake motion was performed.A novel bottom rigid element(BRE)method of the current displacement input model for structural seismic analysis under the multi-support excitations was used to calculate structural dynamic response.In the analysis,pounding between adjacent deck segments was considered.The seismic response of a multi-span bridge subjected to the multi-support excitation,considering not only the traveling-wave effect and partial coherence effect,but also the seismic non-stationary characteristics of multi-support earthquake motion,was simulated using finite element method(FEM).Meanwhile,the seismic response of the bridge under uniform earthquake was also analyzed.Finally,comparative analysis was conducted and some calculation results were shown for pounding effect,under multi-dimensional and multi-support earthquake motion,when performing seismic response analysis of multi-span bridge.Compared with the case of uniform/multi-support/multi-support and multi-dimensional earthquake input,the maximum values of pounding force in the case of multi-support and multi-dimensional earthquake input increase by about 5 8 times;the absolute value of bottom moment and shear force of piers increase by about50%600%and 23.1%900%,respectively.A conclusion can be given that it is very necessary to consider the pounding effect under multi-dimensional and multi-support earthquake motion while performing seismic response analysis of multi-span bridge.展开更多
基金The Program of Tianjin Municipal Science&Technology Project(11ZCZDSY08100)The Program of“One Hundred Talented People”of the Chinese Academy of Sciences(KSCW2-YW-BR-4)National Natural Science Foundation of China(81273275)~~
基金Project supported by Australian Government Overseas Postgraduate Research Scholarship(OPRS)International Postgraduate Awards(IPA)by the University of Sydney and the Foundation of Technology Development in Science of Tongji University.
文摘Sisal filbre is a kind of natural filbre which possesses high specic strength and modu- lus, low price, recycalability, easy availability in some countries. Using sisal filbre as reinforcement to make sisal filbre reinforced polymer composites has aroused great interest of materials scientists and engineers all over the world. Many researches have been done in recent years which include the study of mechanical properties of the composites, nding an ecient way to improve the inter- facial bonding properties between sisal bre and polymeric matrices and bre surface treatment on the mechanical performance of the composites. Though many researches on sisal bre reinforced composites have been done so far, none deals with the fracture properties of this novel composite which is crucial for the actual application of this material. In this research, Charpy impact test and compact tension test were employed to study the fracture toughness of sisal bre reinforced vinyl ester and epoxy composites. The eect of bre surface treatment on the fracture properties of these composites by permanganate and silane was evaluated. The initiation and propagation of the crack were observed with optical microscopy (OM). The fracture morphologies revealed by OM explains the fracture phenomenon of sisal bre reinforced composites.
基金Project(51078242)supported by the National Natural Science Foundation of China
文摘The nonlinear analysis of pounding between bridge deck segments subjected to multi-support excitations and multi-dimensional earthquake motion was performed.A novel bottom rigid element(BRE)method of the current displacement input model for structural seismic analysis under the multi-support excitations was used to calculate structural dynamic response.In the analysis,pounding between adjacent deck segments was considered.The seismic response of a multi-span bridge subjected to the multi-support excitation,considering not only the traveling-wave effect and partial coherence effect,but also the seismic non-stationary characteristics of multi-support earthquake motion,was simulated using finite element method(FEM).Meanwhile,the seismic response of the bridge under uniform earthquake was also analyzed.Finally,comparative analysis was conducted and some calculation results were shown for pounding effect,under multi-dimensional and multi-support earthquake motion,when performing seismic response analysis of multi-span bridge.Compared with the case of uniform/multi-support/multi-support and multi-dimensional earthquake input,the maximum values of pounding force in the case of multi-support and multi-dimensional earthquake input increase by about 5 8 times;the absolute value of bottom moment and shear force of piers increase by about50%600%and 23.1%900%,respectively.A conclusion can be given that it is very necessary to consider the pounding effect under multi-dimensional and multi-support earthquake motion while performing seismic response analysis of multi-span bridge.
