Both single-face vacuum bag curing(SVC) and double-face vacuum bag curing(DVC)can be used in scarf repair of composite structures. But different curing conditions caused by the sealing state may affect the bonding qua...Both single-face vacuum bag curing(SVC) and double-face vacuum bag curing(DVC)can be used in scarf repair of composite structures. But different curing conditions caused by the sealing state may affect the bonding quality of scarf-repaired structures. In this paper, the effect of curing condition on bonding quality of scarf-repaired laminates was experimentally investigated in terms of surface profiles, moisture absorption curves and section profiles. In order to further explore the moisture absorption mechanism, finite element model of the repaired laminates using DVC was established with moisture diffusion of both the adhesive and composite laminates considered. This model was verified by experimental results. Based on the model of DVC case, the model of SVC case was built by changing moisture absorption parameters of the adhesive. Results show that SVC reduces the bonding quality, mainly reflecting in more adhesive inner voids and patch-toparent dislocation. And SVC increases moisture absorption rate and moisture equilibrium content of the adhesive, and its effect on the former is far greater than that on the latter.展开更多
The article reveals the development and analysis of fabric structure for its moisture absorbency property and its application in Civil engineering for curing of concrete. The presence of moisture in concrete and time ...The article reveals the development and analysis of fabric structure for its moisture absorbency property and its application in Civil engineering for curing of concrete. The presence of moisture in concrete and time of curing are the major influencing factors for concrete strength. Normal practice of curing is to wrap the concrete with jute woven fabric and spraying of water. The absorbency characteristics of different GSM (Gram per square meter) of woven and Non-woven fabric were studied. The Non-woven fabric absorbency is superior to woven fabric of same GSM by its three dimensional structure and high pore volume. The strength of concrete cured with Non- woven fabric is 2.1 N/mm2 higher than woven fabric of same 350 GSM. The difference in compressive strength of Non-woven fabric of 350 GSM and 750 GSM is 0.06 N/mm2 which is marginal.展开更多
The influence of surface state on the moisture sensitivity of carbon fiber was analyzed by applying a T800 grade carbon fiber with five different surface conditions,namely,with and without surface oxidation,in the pre...The influence of surface state on the moisture sensitivity of carbon fiber was analyzed by applying a T800 grade carbon fiber with five different surface conditions,namely,with and without surface oxidation,in the presence or absence of sizing agent.The interfacial properties of their composites in the presence of two epoxy matrices（respectively EP07 and EP10） were also characterized by micro-droplet tests.The overall results show that both oxidized and sizing-coated fibers have higher moisture equilibrium content than that of the pristine unsurface-treated fiber,due to higher amount of activated carbon groups.After moisture absorption of the carbon fibers,almost all the fiber/epoxy systems show decrease in the interfacial shear strength and the unsurface-treated fiber system exhibits the largest decline.Moreover,both interfacial shear strength and interlaminar shear strength of carbon fiber/EP10 composite demonstrate better water resistance performance than that of the carbon fiber/EP07 composite,consistent with DSC results of the two resins.展开更多
基金National Natural Science Foundation of China (No. 11472024) for financial support。
文摘Both single-face vacuum bag curing(SVC) and double-face vacuum bag curing(DVC)can be used in scarf repair of composite structures. But different curing conditions caused by the sealing state may affect the bonding quality of scarf-repaired structures. In this paper, the effect of curing condition on bonding quality of scarf-repaired laminates was experimentally investigated in terms of surface profiles, moisture absorption curves and section profiles. In order to further explore the moisture absorption mechanism, finite element model of the repaired laminates using DVC was established with moisture diffusion of both the adhesive and composite laminates considered. This model was verified by experimental results. Based on the model of DVC case, the model of SVC case was built by changing moisture absorption parameters of the adhesive. Results show that SVC reduces the bonding quality, mainly reflecting in more adhesive inner voids and patch-toparent dislocation. And SVC increases moisture absorption rate and moisture equilibrium content of the adhesive, and its effect on the former is far greater than that on the latter.
文摘The article reveals the development and analysis of fabric structure for its moisture absorbency property and its application in Civil engineering for curing of concrete. The presence of moisture in concrete and time of curing are the major influencing factors for concrete strength. Normal practice of curing is to wrap the concrete with jute woven fabric and spraying of water. The absorbency characteristics of different GSM (Gram per square meter) of woven and Non-woven fabric were studied. The Non-woven fabric absorbency is superior to woven fabric of same GSM by its three dimensional structure and high pore volume. The strength of concrete cured with Non- woven fabric is 2.1 N/mm2 higher than woven fabric of same 350 GSM. The difference in compressive strength of Non-woven fabric of 350 GSM and 750 GSM is 0.06 N/mm2 which is marginal.
基金Funded by the National Natural Science Foundation of China(51273007)
文摘The influence of surface state on the moisture sensitivity of carbon fiber was analyzed by applying a T800 grade carbon fiber with five different surface conditions,namely,with and without surface oxidation,in the presence or absence of sizing agent.The interfacial properties of their composites in the presence of two epoxy matrices（respectively EP07 and EP10） were also characterized by micro-droplet tests.The overall results show that both oxidized and sizing-coated fibers have higher moisture equilibrium content than that of the pristine unsurface-treated fiber,due to higher amount of activated carbon groups.After moisture absorption of the carbon fibers,almost all the fiber/epoxy systems show decrease in the interfacial shear strength and the unsurface-treated fiber system exhibits the largest decline.Moreover,both interfacial shear strength and interlaminar shear strength of carbon fiber/EP10 composite demonstrate better water resistance performance than that of the carbon fiber/EP07 composite,consistent with DSC results of the two resins.
