H-steel all-bolted connection steel frame structures with heat preservation and decoration composite wall boards were investigated and the seismic performances of three scaled specimens were studied.The failure modes,...H-steel all-bolted connection steel frame structures with heat preservation and decoration composite wall boards were investigated and the seismic performances of three scaled specimens were studied.The failure modes,hysteresis curves,bearing capacity,ductility,energy dissipation capacity,stiffness degradation and strain distribution were discussed.The calculation method of structural theoretical internal force was presented.The results showed that the overall structural seismic performance was better,and the structural ductility met the demands of elastic-plastic inter-story drift angle for seismic design.The H-steel weak-axis connection structure obtained better energy dissipation capacity,and its bearing capacity and stiffness were slightly different from the strong-axis connection.The heat preservation and decoration performance of composite wallboard and the all-bolted connection of the steel frame realized prefabrication during the whole construction period.The plastic hinge of the steel beam can be moved outwards because of the L-angles,which effectively avoids stress concentration in joint areas and expands the plastic hinge range.The errors between the theoretical structural capacity calculated by the plastic analysis method and the test results were within 2.44%.In addition,structural failure mechanisms and bearing capacities were verified by the finite element(FE)analysis,and the effects of the main parameters on the structures were investigated.The FE verification results were the same as in the test.The research results provide theoretical support and technical guidance for the application of thermal insulation and decorative composite wall panels in H-shaped steel all-bolted steel frames.展开更多
For this study, an intercalation compounding method was used to prepare Chinese fir wood/Ca-montmorillonite (Ca-MMT) composite board to improve its properties such as surface mechanical properties, flame retardance an...For this study, an intercalation compounding method was used to prepare Chinese fir wood/Ca-montmorillonite (Ca-MMT) composite board to improve its properties such as surface mechanical properties, flame retardance and dimensional sta-bility. By virtue of water-soluble phenolic resin (PF), Chinese fir wood and Ca-MMT were mixed by pressure and vacuum impregna-tion. The optimum impregnation technology of Chinese fir wood/Ca-MMT composite board was obtained by using an orthogonal design and a single factor design of pressure and vacuum impregnation, using weight percent gain (WPG) as the basic index. The results are as follows: 1) On the basis of the orthogonal design and an actual experiment, the optimum preparation technology of Chinese fir wood/Ca-MMT composite board is 20% PF resin dispersion concentration (wt%), 1.0 CEC amount of organic intercala-tion agent, 0.098 MPa vacuum degree, 5% concentration of Ca-MMT and 1.0 MPa pressure. 2) The WPG of the composite board samples of 450 mm length was much larger than that of the samples of 600, 750 and 900 mm length. Warm water extraction contrib-uted little to WPG.展开更多
Due to their durability,versatility,and aesthetic value,wood and wood-based composites are widely used as building materials.The fact that these materials are flammable,however,raises a major worry since they might ca...Due to their durability,versatility,and aesthetic value,wood and wood-based composites are widely used as building materials.The fact that these materials are flammable,however,raises a major worry since they might cause fire hazards and significant loss of life and property.The article investigates the variables that affect fire performance as well as the various fire-retardant treatments and their mechanisms.The current developments and challenges in improving the fire performance of wood and wood-based composites treated with fire-retardant materials are summarized in this paper.Nanoparticles,organic chemicals,and densification are some recent developments in fire-retardant treatments that are also emphasized.Key points from the review are summarized,along with potential areas for further research and development.展开更多
In this study,the deformation and stress distribution of printed circuit board(PCB)with different thickness and composite materials under a shock loading were analyzed by the finite element analysis.The standard 8-lay...In this study,the deformation and stress distribution of printed circuit board(PCB)with different thickness and composite materials under a shock loading were analyzed by the finite element analysis.The standard 8-layer PCB subjected to a shock loading 1500 g was evaluated first.Moreover,the finite element models of the PCB with different thickness by stacking various number of layers were discussed.In addition to changing thickness,the core material of PCB was replaced from woven E-glass/epoxy to woven carbon fiber/epoxy for structural enhancement.The non-linear material property of copper foil was considered in the analysis.The results indicated that a thicker PCB has lower stress in the copper foil in PCBs under the shock loading.The stress difference between the thicker PCB(2.6 mm)and thinner PCB(0.6 mm)is around 5%.Using woven carbon fiber/epoxy as core material could lower the stress of copper foil around 6.6%under the shock loading 1500 g for the PCB with 0.6 mm thickness.On the other hand,the stress level is under the failure strength of PCBs with carbon fiber/epoxy core layers and thickness 2.6 mm when the peak acceleration changes from 1500 g to 5000 g.This study could provide a reference for the design and proper applications of the PCB with different thickness and composite materials.展开更多
In order to study of adhesive which is applicable to the production of high strength four layer composite corrugated board,the composite corrugated medium was respectively coated with cassava starch adhesive,environme...In order to study of adhesive which is applicable to the production of high strength four layer composite corrugated board,the composite corrugated medium was respectively coated with cassava starch adhesive,environmental-friendly modified water glass binder,CP-88 starch adhesive,polyvinyl alcohol adhesive and polyvinyl acetate adhesive,then the edgewise crush resistance and flat crush resistance contrast experiment on produced corrugated board samples was tested.The experiment results demonstrated that the produced corrugated board with environmental-friendly modified water glass binder had high edgewise crush resistance,general flat crush resistance and more economic,so the environmental-friendly modified water glass binder can be used for the production of high strength four layer composite corrugated board.展开更多
A novel low-temperature alkaline smelting process is proposed to convert and separate amphoteric metals in crushed metal enrichment originated from waste printed circuit boards. The central composite design was used t...A novel low-temperature alkaline smelting process is proposed to convert and separate amphoteric metals in crushed metal enrichment originated from waste printed circuit boards. The central composite design was used to optimize the operating parameters,in which mass ratio of Na OH-to-CME, smelting temperature and smelting time were chosen as the variables, and the conversions of amphoteric metals tin, lead, aluminum and zinc were response parameters. Second-order polynomial models of high significance and3 D response surface plots were constructed to show the relationship between the responses and the variables. Optimum area of80%-85% Pb conversion and over 95% Sn conversion was obtained by the overlaid contours at mass ratio of Na OH-to-CME of4.5-5.0, smelting temperature of 653-723 K, smelting time of 90-120 min. The models were validated experimentally in the optimum area, and the results demonstrate that these models are reliable and accurate in predicting the smelting process.展开更多
We studied the effects of nanoparticles of organo-silane(NOS) compounds in the size range of20–80 nm on physical and mechanical properties in medium density fiberboard,and used NOS at four consumption levels of 0,50,...We studied the effects of nanoparticles of organo-silane(NOS) compounds in the size range of20–80 nm on physical and mechanical properties in medium density fiberboard,and used NOS at four consumption levels of 0,50,100,and 150 g kg-1dry wood fibers.Density of all treatments was kept constant at 0.67 g cm-3.The water-repellent property of organo-silane significantly reduced water absorption(WA) and thickness swelling but mechanical properties declined due to the reduced proportion of wood-fiber as organo-silane was added to the matrix:the compression ratio of MDF panels and the integrity among wood-fibers both declined,resulting in reduced mechanical properties.We recommend use of 50 g of NOS/kg wood-fiber to improve WA and thickness swelling while retaining acceptable mechanical properties.展开更多
We studied the effect of wollastonite nanofibers on fluid flow in medium-density fiberboard(MDF).Nanowollastonite(NW) was applied in MDF at 10 %,based on the dry weight of wood fibers. We also tested chicken feathers ...We studied the effect of wollastonite nanofibers on fluid flow in medium-density fiberboard(MDF).Nanowollastonite(NW) was applied in MDF at 10 %,based on the dry weight of wood fibers. We also tested chicken feathers as an additive to the matrix at 5 and 10 %by weight. The weight of feathers was reduced from the wood fibers to keep the density of the panels constant(0.66 g cm-3). Wollastonite nanofibers acted as filler in the matrix and significantly decreased gas and liquid permeability. Higher thermal conductivity of the NW-treated MDF-mats resulted in a better cure of resin, and consequently more integrity in the composite-matrix and lower permeability. The water-repellant property of wollastonite also contributed to the decrease in liquid permeability.Feathers reduced gas and liquid permeability due to the hydrophobic nature of keratin, as well as its formation as a physical barrier towards passing of fluids. Ten percent feather content proved too high and some checks and cracks occurred in the core of the panels after hot-pressing.Panels with 5 %-feather content resulted in both lower fluid flow and adequate physical integrity in the core section of the MDF-matrix.展开更多
文摘H-steel all-bolted connection steel frame structures with heat preservation and decoration composite wall boards were investigated and the seismic performances of three scaled specimens were studied.The failure modes,hysteresis curves,bearing capacity,ductility,energy dissipation capacity,stiffness degradation and strain distribution were discussed.The calculation method of structural theoretical internal force was presented.The results showed that the overall structural seismic performance was better,and the structural ductility met the demands of elastic-plastic inter-story drift angle for seismic design.The H-steel weak-axis connection structure obtained better energy dissipation capacity,and its bearing capacity and stiffness were slightly different from the strong-axis connection.The heat preservation and decoration performance of composite wallboard and the all-bolted connection of the steel frame realized prefabrication during the whole construction period.The plastic hinge of the steel beam can be moved outwards because of the L-angles,which effectively avoids stress concentration in joint areas and expands the plastic hinge range.The errors between the theoretical structural capacity calculated by the plastic analysis method and the test results were within 2.44%.In addition,structural failure mechanisms and bearing capacities were verified by the finite element(FE)analysis,and the effects of the main parameters on the structures were investigated.The FE verification results were the same as in the test.The research results provide theoretical support and technical guidance for the application of thermal insulation and decorative composite wall panels in H-shaped steel all-bolted steel frames.
基金the National Natural Science Foundation of China (Grant No.30271055)
文摘For this study, an intercalation compounding method was used to prepare Chinese fir wood/Ca-montmorillonite (Ca-MMT) composite board to improve its properties such as surface mechanical properties, flame retardance and dimensional sta-bility. By virtue of water-soluble phenolic resin (PF), Chinese fir wood and Ca-MMT were mixed by pressure and vacuum impregna-tion. The optimum impregnation technology of Chinese fir wood/Ca-MMT composite board was obtained by using an orthogonal design and a single factor design of pressure and vacuum impregnation, using weight percent gain (WPG) as the basic index. The results are as follows: 1) On the basis of the orthogonal design and an actual experiment, the optimum preparation technology of Chinese fir wood/Ca-MMT composite board is 20% PF resin dispersion concentration (wt%), 1.0 CEC amount of organic intercala-tion agent, 0.098 MPa vacuum degree, 5% concentration of Ca-MMT and 1.0 MPa pressure. 2) The WPG of the composite board samples of 450 mm length was much larger than that of the samples of 600, 750 and 900 mm length. Warm water extraction contrib-uted little to WPG.
基金Ministry of Higher Education Malaysia for their Fundamental Research Grant Scheme (FRGS)FRGS/1/2022/TK10/UMS/02/1the International Tropical Timber Organization for the ITTO Fellowship Pro-gramme (No.070/21A)。
文摘Due to their durability,versatility,and aesthetic value,wood and wood-based composites are widely used as building materials.The fact that these materials are flammable,however,raises a major worry since they might cause fire hazards and significant loss of life and property.The article investigates the variables that affect fire performance as well as the various fire-retardant treatments and their mechanisms.The current developments and challenges in improving the fire performance of wood and wood-based composites treated with fire-retardant materials are summarized in this paper.Nanoparticles,organic chemicals,and densification are some recent developments in fire-retardant treatments that are also emphasized.Key points from the review are summarized,along with potential areas for further research and development.
基金the support from Ministry of Science and Technology,Taiwan,R.O.C.,through grant MOST-105-2221-E-007-031-MY3.
文摘In this study,the deformation and stress distribution of printed circuit board(PCB)with different thickness and composite materials under a shock loading were analyzed by the finite element analysis.The standard 8-layer PCB subjected to a shock loading 1500 g was evaluated first.Moreover,the finite element models of the PCB with different thickness by stacking various number of layers were discussed.In addition to changing thickness,the core material of PCB was replaced from woven E-glass/epoxy to woven carbon fiber/epoxy for structural enhancement.The non-linear material property of copper foil was considered in the analysis.The results indicated that a thicker PCB has lower stress in the copper foil in PCBs under the shock loading.The stress difference between the thicker PCB(2.6 mm)and thinner PCB(0.6 mm)is around 5%.Using woven carbon fiber/epoxy as core material could lower the stress of copper foil around 6.6%under the shock loading 1500 g for the PCB with 0.6 mm thickness.On the other hand,the stress level is under the failure strength of PCBs with carbon fiber/epoxy core layers and thickness 2.6 mm when the peak acceleration changes from 1500 g to 5000 g.This study could provide a reference for the design and proper applications of the PCB with different thickness and composite materials.
文摘In order to study of adhesive which is applicable to the production of high strength four layer composite corrugated board,the composite corrugated medium was respectively coated with cassava starch adhesive,environmental-friendly modified water glass binder,CP-88 starch adhesive,polyvinyl alcohol adhesive and polyvinyl acetate adhesive,then the edgewise crush resistance and flat crush resistance contrast experiment on produced corrugated board samples was tested.The experiment results demonstrated that the produced corrugated board with environmental-friendly modified water glass binder had high edgewise crush resistance,general flat crush resistance and more economic,so the environmental-friendly modified water glass binder can be used for the production of high strength four layer composite corrugated board.
基金Projects(51074190,51234009)supported by the National Natural Science Foundation of ChinaProject(2014DFA90520)supported by International Cooperation Program of Ministry of Science of ChinaProject(20110162110049)supported by the Doctoral Scientific Fund Project of the Ministry of Education of China
文摘A novel low-temperature alkaline smelting process is proposed to convert and separate amphoteric metals in crushed metal enrichment originated from waste printed circuit boards. The central composite design was used to optimize the operating parameters,in which mass ratio of Na OH-to-CME, smelting temperature and smelting time were chosen as the variables, and the conversions of amphoteric metals tin, lead, aluminum and zinc were response parameters. Second-order polynomial models of high significance and3 D response surface plots were constructed to show the relationship between the responses and the variables. Optimum area of80%-85% Pb conversion and over 95% Sn conversion was obtained by the overlaid contours at mass ratio of Na OH-to-CME of4.5-5.0, smelting temperature of 653-723 K, smelting time of 90-120 min. The models were validated experimentally in the optimum area, and the results demonstrate that these models are reliable and accurate in predicting the smelting process.
基金conducted as a joint research projectfinanced by SRTTU(Iran)UPM(Malaysia)
文摘We studied the effects of nanoparticles of organo-silane(NOS) compounds in the size range of20–80 nm on physical and mechanical properties in medium density fiberboard,and used NOS at four consumption levels of 0,50,100,and 150 g kg-1dry wood fibers.Density of all treatments was kept constant at 0.67 g cm-3.The water-repellent property of organo-silane significantly reduced water absorption(WA) and thickness swelling but mechanical properties declined due to the reduced proportion of wood-fiber as organo-silane was added to the matrix:the compression ratio of MDF panels and the integrity among wood-fibers both declined,resulting in reduced mechanical properties.We recommend use of 50 g of NOS/kg wood-fiber to improve WA and thickness swelling while retaining acceptable mechanical properties.
基金supported by Shahid Rajaee Teacher Training University
文摘We studied the effect of wollastonite nanofibers on fluid flow in medium-density fiberboard(MDF).Nanowollastonite(NW) was applied in MDF at 10 %,based on the dry weight of wood fibers. We also tested chicken feathers as an additive to the matrix at 5 and 10 %by weight. The weight of feathers was reduced from the wood fibers to keep the density of the panels constant(0.66 g cm-3). Wollastonite nanofibers acted as filler in the matrix and significantly decreased gas and liquid permeability. Higher thermal conductivity of the NW-treated MDF-mats resulted in a better cure of resin, and consequently more integrity in the composite-matrix and lower permeability. The water-repellant property of wollastonite also contributed to the decrease in liquid permeability.Feathers reduced gas and liquid permeability due to the hydrophobic nature of keratin, as well as its formation as a physical barrier towards passing of fluids. Ten percent feather content proved too high and some checks and cracks occurred in the core of the panels after hot-pressing.Panels with 5 %-feather content resulted in both lower fluid flow and adequate physical integrity in the core section of the MDF-matrix.
