To investigate the long-term performance of the packaged fiber Bragg grating(FBG)sensors embedded in civil infrastructure for strain monitoring,in this paper,the influence of host matrix’s creep effect on the behavio...To investigate the long-term performance of the packaged fiber Bragg grating(FBG)sensors embedded in civil infrastructure for strain monitoring,in this paper,the influence of host matrix’s creep effect on the behavior of the FBG sensors was systematically studied through theoretical,numerical,and experimental analysis.A theoretical strain transfer analysis between the optic fiber,packaging layer,and host matrix to consider the creep effect of the host matrix was performed accordingly for long-term strain monitoring.Parametric studies were carried out using numerical analysis for FBG sensors packaged with glass fiber reinforced plastic(GFRP),also known as FBG-GFRP sensors in concrete,as an example.The results show that embedded in a creep medium,an acceptable long-term performance of packaged FBG sensors requires the packaging layer to have a minimum length and maximum thickness.Laboratory long-term creep tests using epoxy resin and concrete as host matrix for FBG-GFRP sensors also clearly demonstrated that the influence of creep effect cannot be ignored for strain measurements if the host matrix has a creep potential and the developed correction model performed well to reduce measurement errors of such sensors in creep medium.展开更多
Relatively well crystallized and high aspect ratio Mg-Al layered double hydroxides（LDHs） were prepared by coprecipitation process in aqueous solution and further rehydrated to an organic modified LDH（OLDH） in the ...Relatively well crystallized and high aspect ratio Mg-Al layered double hydroxides（LDHs） were prepared by coprecipitation process in aqueous solution and further rehydrated to an organic modified LDH（OLDH） in the presence of surfactant. The intercalated structure and high aspect ratio of OLDH were verified by X-ray diffraction（XRD） and scanning electron microscopy（SEM）. A series of poly（propylene carbonate）（PPC）/OLDH composite films with different contents of OLDH were prepared via a melt-blending method. Their cross section morphologies, gas barrier properties and tensile strength were investigated as a function of OLDH contents. SEM results show that OLDH platelets are well dispersed within the composites and oriented parallel to the composite sheet plane. The gas barrier properties and tensile strength are obviously enhanced upon the incorporation of OLDH. Particularly, PPC/2%OLDH film exhibits the best barrier properties among all the composite films. Compared with pure PPC, the oxygen permeability coefficient（OP） and water vapor permeability coefficient（WVP） is reduced by 54% and 17% respectively with 2% OLDH addition. Furthermore, the tensile strength of PPC/2%OLDH is 83% higher than that of pure PPC with only small lose of elongation at break. Therefore, PPC/OLDH composite films show great potential application in packaging materials due to its biodegradable properties, superior oxygen and moisture barrier characteristics.展开更多
基金supported by the The National Key R&D Program of China[2018FYC0705606]。
文摘To investigate the long-term performance of the packaged fiber Bragg grating(FBG)sensors embedded in civil infrastructure for strain monitoring,in this paper,the influence of host matrix’s creep effect on the behavior of the FBG sensors was systematically studied through theoretical,numerical,and experimental analysis.A theoretical strain transfer analysis between the optic fiber,packaging layer,and host matrix to consider the creep effect of the host matrix was performed accordingly for long-term strain monitoring.Parametric studies were carried out using numerical analysis for FBG sensors packaged with glass fiber reinforced plastic(GFRP),also known as FBG-GFRP sensors in concrete,as an example.The results show that embedded in a creep medium,an acceptable long-term performance of packaged FBG sensors requires the packaging layer to have a minimum length and maximum thickness.Laboratory long-term creep tests using epoxy resin and concrete as host matrix for FBG-GFRP sensors also clearly demonstrated that the influence of creep effect cannot be ignored for strain measurements if the host matrix has a creep potential and the developed correction model performed well to reduce measurement errors of such sensors in creep medium.
基金financially supported by the National Natural Science Foundation of China(No.21376276)the Specialfunded Program on National Key Scientific Instruments and Equipment Development of China(No.2012YQ230043)+1 种基金Guangdong Province Sci&Tech Bureau(Key Strategic Project No.2008A080800024)the Fundamental Research Funds for the Central Universities
文摘Relatively well crystallized and high aspect ratio Mg-Al layered double hydroxides（LDHs） were prepared by coprecipitation process in aqueous solution and further rehydrated to an organic modified LDH（OLDH） in the presence of surfactant. The intercalated structure and high aspect ratio of OLDH were verified by X-ray diffraction（XRD） and scanning electron microscopy（SEM）. A series of poly（propylene carbonate）（PPC）/OLDH composite films with different contents of OLDH were prepared via a melt-blending method. Their cross section morphologies, gas barrier properties and tensile strength were investigated as a function of OLDH contents. SEM results show that OLDH platelets are well dispersed within the composites and oriented parallel to the composite sheet plane. The gas barrier properties and tensile strength are obviously enhanced upon the incorporation of OLDH. Particularly, PPC/2%OLDH film exhibits the best barrier properties among all the composite films. Compared with pure PPC, the oxygen permeability coefficient（OP） and water vapor permeability coefficient（WVP） is reduced by 54% and 17% respectively with 2% OLDH addition. Furthermore, the tensile strength of PPC/2%OLDH is 83% higher than that of pure PPC with only small lose of elongation at break. Therefore, PPC/OLDH composite films show great potential application in packaging materials due to its biodegradable properties, superior oxygen and moisture barrier characteristics.
