Fracture is a common failure form of poplar laminated veneer lumber(LVL).In the present work,we performed an experimental study on the mode-I along-grain interlaminar fracture,mode-I cross-grain interlaminar fracture,...Fracture is a common failure form of poplar laminated veneer lumber(LVL).In the present work,we performed an experimental study on the mode-I along-grain interlaminar fracture,mode-I cross-grain interlaminar fracture,and mode-II interlaminar fracture of poplar LVL.We investigated stress mechanisms,failure modes,and fracture toughness values of the different fracture types.The experimental results revealed that the crack in the mode-I along-grain interlaminar fracture specimen propagated along the prefabricated crack direction,and the crack tip broke.The mode-I cross-grain interlaminar fracture specimen had cracks in the vertical direction near the prefabricated crack.In the mode-II interlaminar fracture specimen,cracks appeared along the initial prefabricated crack direction.The load–displacement curves of these three specimens were linear in the early stage of loading.With the increase in the load,a nonlinear segment appeared before crack propagation and a descending segment appeared after crack propagation.The nonlinear segments of the mode-I along-grain interlaminar fracture and mode-II interlaminar fracture were very short,and cracks expanded quickly after their initiation,resulting in brit-tle fracture.The nonlinear segment of the mode-I cross-grain interlaminar fracture was long,resulting in plastic failure.The average toughness values of the mode-I along-grain interlaminar fracture,mode-I cross-grain inter-laminar fracture,and mode-II interlaminar fracture were 15.43,270.15,and 39.72 MPa·mm^(1/2),respectively.展开更多
Due to the continuously increasing demand for building materials across the world,it is necessary to use renewable materials in place of the existing nonrenewable materials in construction projects.Bamboo is a fast-gr...Due to the continuously increasing demand for building materials across the world,it is necessary to use renewable materials in place of the existing nonrenewable materials in construction projects.Bamboo is a fast-growing flowering plant that may be used as a renewable material in construction.The use of bamboo in the construction of buildings can improve its long-term carbon fixation capacity and economic benefits.Although bamboo has the advantages of superior performance,low carbon content,high energy-saving and emission-reducing capacity,bamboo is an anisotropic material,which has many factors affecting its material performance,large variability of material performance,lack of systematic research,and the use of bamboo as the main building material is not always limited.This paper systematically summarizes the research status of bamboo as a building material from the aspects of bamboo composition,gradation,material properties,bamboo building components,connection nodes,and use of artificial boards.On this basis,some constructive suggestions are put forward for the further study of bamboo in the field of architecture.展开更多
One of the large-scale industrial applications of Moso bamboo and poplar in China is the production of standardized fiberboard.When making fiberboard,a steam blasting pretreatment without the addition of traditional a...One of the large-scale industrial applications of Moso bamboo and poplar in China is the production of standardized fiberboard.When making fiberboard,a steam blasting pretreatment without the addition of traditional adhesives has become increasingly popular because of its environmental friendliness and wide applicability.In this study,the steam explosion pretreatment of Moso bamboo and poplar was conducted.The steam explosion pressure and holding time were varied to determine the influence of these factors on fiber quality by investigating the morphology of the fiber,the mass ratio of the unexploded specimen at the end face,the chemical composition,and the tensile strength.The following conclusions were drawn:As the steam burst pressure and holding time increased,more cellulose and hemicellulose degradation occurred(the degradation of hemicellulose was greater than that of cellulose),the lignin content rose,and the fiber bundle strength decreased.The degradation of bamboo cellulose was slightly higher than that of poplar,and the degradation of poplar hemicellulose was significantly faster than that of bamboo.Furthermore,increasing the steam explosion pressure and pressure holding time could not effectively increase the lignin content.It is recommended to use a steam blasting pressure of 2.5 MPa or 3.0 MPa and a holding time of 180 s to perform steam blasting on bamboo and poplar specimens.展开更多
基金the National Natural Science Foundation of China(Grant No.51878590)the Jiangsu Provincial Department of Housing and Construction(Grant Nos.2019ZD092,2020ZD40,2020ZD42)the Sixth Phase of“333 Project”Training Objects in Jiangsu Province and Jiangsu Province High-Level Talent Selection Training(Grant No.JNHB-127)for their financial support.
文摘Fracture is a common failure form of poplar laminated veneer lumber(LVL).In the present work,we performed an experimental study on the mode-I along-grain interlaminar fracture,mode-I cross-grain interlaminar fracture,and mode-II interlaminar fracture of poplar LVL.We investigated stress mechanisms,failure modes,and fracture toughness values of the different fracture types.The experimental results revealed that the crack in the mode-I along-grain interlaminar fracture specimen propagated along the prefabricated crack direction,and the crack tip broke.The mode-I cross-grain interlaminar fracture specimen had cracks in the vertical direction near the prefabricated crack.In the mode-II interlaminar fracture specimen,cracks appeared along the initial prefabricated crack direction.The load–displacement curves of these three specimens were linear in the early stage of loading.With the increase in the load,a nonlinear segment appeared before crack propagation and a descending segment appeared after crack propagation.The nonlinear segments of the mode-I along-grain interlaminar fracture and mode-II interlaminar fracture were very short,and cracks expanded quickly after their initiation,resulting in brit-tle fracture.The nonlinear segment of the mode-I cross-grain interlaminar fracture was long,resulting in plastic failure.The average toughness values of the mode-I along-grain interlaminar fracture,mode-I cross-grain inter-laminar fracture,and mode-II interlaminar fracture were 15.43,270.15,and 39.72 MPa·mm^(1/2),respectively.
基金We thank Jiangsu Province High-level Talent Selection Training(JNHB-127)the National Key R&D Program of China(2017YFC0703501)+4 种基金the National Natural Science Foundation of China(51878590)Jiangsu Provincial Department of Housing and construction(2019ZD092)the Natural Science Foundation of Jiangsu Province(Grant Nos.BK20170926 and BK20150878)the Yangzhou Science and Technology Project(YZ2019047)College Research Project(2019xjzk014)for their funding.
文摘Due to the continuously increasing demand for building materials across the world,it is necessary to use renewable materials in place of the existing nonrenewable materials in construction projects.Bamboo is a fast-growing flowering plant that may be used as a renewable material in construction.The use of bamboo in the construction of buildings can improve its long-term carbon fixation capacity and economic benefits.Although bamboo has the advantages of superior performance,low carbon content,high energy-saving and emission-reducing capacity,bamboo is an anisotropic material,which has many factors affecting its material performance,large variability of material performance,lack of systematic research,and the use of bamboo as the main building material is not always limited.This paper systematically summarizes the research status of bamboo as a building material from the aspects of bamboo composition,gradation,material properties,bamboo building components,connection nodes,and use of artificial boards.On this basis,some constructive suggestions are put forward for the further study of bamboo in the field of architecture.
基金We thank Jiangsu Province High-level Talent Selection Training(JNHB-127)the National Key R&D Program of China(2017YFC0703501)+5 种基金the National Natural Science Foundation of China(51878590)Jiangsu Provincial Department of Housing and construction(2018ZD117 and 2019ZD092)the Natural Science Foundation of Jiangsu Province(Grant Nos.BK20170926 and BK20150878)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(Grant No.19KJD220002)the Yangzhou Science and Technology Project(YZ2019047)College Research Project(2019xjzk014)for their funding.
文摘One of the large-scale industrial applications of Moso bamboo and poplar in China is the production of standardized fiberboard.When making fiberboard,a steam blasting pretreatment without the addition of traditional adhesives has become increasingly popular because of its environmental friendliness and wide applicability.In this study,the steam explosion pretreatment of Moso bamboo and poplar was conducted.The steam explosion pressure and holding time were varied to determine the influence of these factors on fiber quality by investigating the morphology of the fiber,the mass ratio of the unexploded specimen at the end face,the chemical composition,and the tensile strength.The following conclusions were drawn:As the steam burst pressure and holding time increased,more cellulose and hemicellulose degradation occurred(the degradation of hemicellulose was greater than that of cellulose),the lignin content rose,and the fiber bundle strength decreased.The degradation of bamboo cellulose was slightly higher than that of poplar,and the degradation of poplar hemicellulose was significantly faster than that of bamboo.Furthermore,increasing the steam explosion pressure and pressure holding time could not effectively increase the lignin content.It is recommended to use a steam blasting pressure of 2.5 MPa or 3.0 MPa and a holding time of 180 s to perform steam blasting on bamboo and poplar specimens.
