The nonlinear stability of sandwich cylindrical shells comprising porous functionally graded material(FGM) and carbon nanotube reinforced composite(CNTRC)layers subjected to uniform temperature rise is investigated. T...The nonlinear stability of sandwich cylindrical shells comprising porous functionally graded material(FGM) and carbon nanotube reinforced composite(CNTRC)layers subjected to uniform temperature rise is investigated. Two sandwich models corresponding to CNTRC and FGM face sheets are proposed. Carbon nanotubes(CNTs) in the CNTRC layer are embedded into a matrix according to functionally graded distributions. The effects of porosity in the FGM and the temperature dependence of properties of all constituent materials are considered. The effective properties of the porous FGM and CNTRC are determined by using the modified and extended versions of a linear mixture rule, respectively. The basic equations governing the stability problem of thin sandwich cylindrical shells are established within the framework of the Donnell shell theory including the von K’arm’an-Donnell nonlinearity. These equations are solved by using the multi-term analytical solutions and the Galerkin method for simply supported shells.The critical buckling temperatures and postbuckling paths are determined through an iteration procedure. The study reveals that the sandwich shell model with a CNTRC core layer and relatively thin porous FGM face sheets can have the best capacity of thermal load carrying. In addition, unlike the cases of mechanical loads, porosities have beneficial effects on the nonlinear stability of sandwich shells under the thermal load. It is suggested that an appropriate combination of advantages of FGM and CNTRC can result in optimal efficiency for advanced sandwich structures.展开更多
In recent years,composite materials have been used in many industries such as in automotive,aerospace,telecommunication,marine,furniture,construction and defence.Body amour and tank spall liners are examples of the us...In recent years,composite materials have been used in many industries such as in automotive,aerospace,telecommunication,marine,furniture,construction and defence.Body amour and tank spall liners are examples of the use of composites in defence industry.Composites have many different attributes that are unique over conventional materials like metals,polymers and ceramics.Those attributes include light weight,high specific stiffness and strength properties,corrosion resistance,aesthetically pleasing and ease of fabrication.Advanced composites such as aramid and carbon fibre polymer composites,metal matrix composites,ceramic matrix composites,and nanocomposites are among material contenders in defence technology applications requiring excellent structural integrity.Composites are also used in some non-structural applications in selected components utilising the low cost advantage of glass fibre and natural fibre composites.展开更多
An overview is given of recent development of mechanochemical processes for the preparation of advanced ceramics.Some fundamental mechanical effects are firstly compared and discussed.Several important application fie...An overview is given of recent development of mechanochemical processes for the preparation of advanced ceramics.Some fundamental mechanical effects are firstly compared and discussed.Several important application fields are listed as follow,stemming from oxide materials,non-oxide materials,and composite materials to nano-structured materials.展开更多
Europium and terbium coordination polymers of pyridine-3-carboxylic acid were in-situ composed with ethyt methacrylate （ EMA ）. With the polymerization of EMA monomer and the formation of europium and terbium coordi...Europium and terbium coordination polymers of pyridine-3-carboxylic acid were in-situ composed with ethyt methacrylate （ EMA ）. With the polymerization of EMA monomer and the formation of europium and terbium coordination polymers of pyridiae- 3-carboxylic acid, the transparent hybrid thick fihns composed of [ Eu（ NIC ）3 ]n （ [ Tb（ NIC）3 ]n ） and poly ethyl mettuwrylate （ PEMA ） have been prepared. The luminescence properties and energy transfer of these polymeric composites were studied with absorption spectra, fluorescent excitation trod emission spectra in detail. All the hybrid thick films composed of terbium coordination polymer show the characteristic strong green emission of terbium ions, which implies the same energy transfer mechanism as the pure complex and the hybrid composite film is a suitable sabstrate for the luminescence of terbium ions. In the range of camposing concentration of luminescent species （0.01,0.025,0.05,0.1 mmol /15 mL EMA ）, emission intensities increase with the increasing of corresponding composing concentration and the concentration quenching effect does not take place.展开更多
基金the Vietnam National Foundation for Science and Technology Development(NAFOSTED)(No.107.02-2019.318)。
文摘The nonlinear stability of sandwich cylindrical shells comprising porous functionally graded material(FGM) and carbon nanotube reinforced composite(CNTRC)layers subjected to uniform temperature rise is investigated. Two sandwich models corresponding to CNTRC and FGM face sheets are proposed. Carbon nanotubes(CNTs) in the CNTRC layer are embedded into a matrix according to functionally graded distributions. The effects of porosity in the FGM and the temperature dependence of properties of all constituent materials are considered. The effective properties of the porous FGM and CNTRC are determined by using the modified and extended versions of a linear mixture rule, respectively. The basic equations governing the stability problem of thin sandwich cylindrical shells are established within the framework of the Donnell shell theory including the von K’arm’an-Donnell nonlinearity. These equations are solved by using the multi-term analytical solutions and the Galerkin method for simply supported shells.The critical buckling temperatures and postbuckling paths are determined through an iteration procedure. The study reveals that the sandwich shell model with a CNTRC core layer and relatively thin porous FGM face sheets can have the best capacity of thermal load carrying. In addition, unlike the cases of mechanical loads, porosities have beneficial effects on the nonlinear stability of sandwich shells under the thermal load. It is suggested that an appropriate combination of advantages of FGM and CNTRC can result in optimal efficiency for advanced sandwich structures.
文摘In recent years,composite materials have been used in many industries such as in automotive,aerospace,telecommunication,marine,furniture,construction and defence.Body amour and tank spall liners are examples of the use of composites in defence industry.Composites have many different attributes that are unique over conventional materials like metals,polymers and ceramics.Those attributes include light weight,high specific stiffness and strength properties,corrosion resistance,aesthetically pleasing and ease of fabrication.Advanced composites such as aramid and carbon fibre polymer composites,metal matrix composites,ceramic matrix composites,and nanocomposites are among material contenders in defence technology applications requiring excellent structural integrity.Composites are also used in some non-structural applications in selected components utilising the low cost advantage of glass fibre and natural fibre composites.
基金National Natural Science Foundation of China(No.20671035)the Open Fund of Key Laboratory of High Performance Ceramics and Superfine Microstructures,Shanghai Institute of Ceramics,Chinese Academy of Sciences.
文摘An overview is given of recent development of mechanochemical processes for the preparation of advanced ceramics.Some fundamental mechanical effects are firstly compared and discussed.Several important application fields are listed as follow,stemming from oxide materials,non-oxide materials,and composite materials to nano-structured materials.
文摘Europium and terbium coordination polymers of pyridine-3-carboxylic acid were in-situ composed with ethyt methacrylate （ EMA ）. With the polymerization of EMA monomer and the formation of europium and terbium coordination polymers of pyridiae- 3-carboxylic acid, the transparent hybrid thick fihns composed of [ Eu（ NIC ）3 ]n （ [ Tb（ NIC）3 ]n ） and poly ethyl mettuwrylate （ PEMA ） have been prepared. The luminescence properties and energy transfer of these polymeric composites were studied with absorption spectra, fluorescent excitation trod emission spectra in detail. All the hybrid thick films composed of terbium coordination polymer show the characteristic strong green emission of terbium ions, which implies the same energy transfer mechanism as the pure complex and the hybrid composite film is a suitable sabstrate for the luminescence of terbium ions. In the range of camposing concentration of luminescent species （0.01,0.025,0.05,0.1 mmol /15 mL EMA ）, emission intensities increase with the increasing of corresponding composing concentration and the concentration quenching effect does not take place.
