A physically accurate and computationally effective pure finite element method （FEM） was developed to simulate the isothermal resin infusing process. The FEM was based on conservation of resin muss at and instant of...A physically accurate and computationally effective pure finite element method （FEM） was developed to simulate the isothermal resin infusing process. The FEM was based on conservation of resin muss at and instant of time and was objective of resin film infusion （RFI） fiber impregnation and mold filling . The developed computer code was able to simulate the resin infusing visually. A numerical example presented here demonstrated that compared with traditional finite element/ control-volume （FE/CV）, and FEM was physically accurate and computationally efficient.展开更多
The most common process to manufacture advanced composites is the costly autoclave.One of the out-of-autoclave alternatives is the low-cost vacuum assisted resin infusion(VARI)which produces quality parts with less po...The most common process to manufacture advanced composites is the costly autoclave.One of the out-of-autoclave alternatives is the low-cost vacuum assisted resin infusion(VARI)which produces quality parts with less pollution.Epoxy resin is a widely used composite matrix resin,but its high flammability limits its use as interior composite parts for vehicles.The usual flame retardant for epoxy involves halogen,which is effective but has high smoke toxicity.As a result,halogen-free flame retardant epoxy resin systems become dominant.In this paper,phosphorus flame retardant was combined with benzoxazine(BOZ)to produce synergistic effect and achieve satisfactory flame retardance,as well as mechanical improvement for the epoxy resin.Differential scanning calorimetry(DSC),dynamic mechanical analysis(DMA),thermal gravitational analysis(TGA),the cone calorimeter(CC),and limiting oxygen index(LOI)were used to characterize the resins.The results showed significant improvement on the flame retardance of the synergistically modified resins.Specifically,the carbon residue increased by 113.6%,and the char thickness increased by 6 to 7 times,compared to those of the flammable benchmark resin.The LOI reached 33 and passed the UL94 V-0 vertical burn rating.The modified resins also exhibited adequate stability and viscosity suitable for VARI processes.展开更多
An experimental procedure was designed to monitor the preform thickness change real-time throughout the vacuum assisted resin infusion( VARI) process. Two kinds of liquid with different viscosity were infused with dif...An experimental procedure was designed to monitor the preform thickness change real-time throughout the vacuum assisted resin infusion( VARI) process. Two kinds of liquid with different viscosity were infused with different post-filling time. The variation of the part thickness during the VARI process was studied. And the effect of the post-filling time on the part thickness was investigated.The results indicate that the compaction behavior of the preform can be divided into three stages,and the fiber volume fraction varies with the post-filling time in a similar sinusoid form. In addition,the post-filling should be overtime for the greatest fiber volume fraction,and when the resin is infused with higher viscosity,the greatest fiber volume fraction is higher.展开更多
The chemorheological behaviors of a low viscosity epoxy resin system （Huntsman 1564/3486） for vacuum infusion moulding process （VIMP） were studied with viscosity experiments.The dual-Arrhenius rheological model an...The chemorheological behaviors of a low viscosity epoxy resin system （Huntsman 1564/3486） for vacuum infusion moulding process （VIMP） were studied with viscosity experiments.The dual-Arrhenius rheological model and the engineering viscosity model were established and compared with the experimental data.The result showed that the viscosity in the earlier stage calculated by dual-Arrhenius model were smaller than the experimental data,while the data calculated by the engineering model were larger.Combining the two models together can predict the rheological behaviors of the resin system in a more credible manner.The processing windows of the resin system for VIMP were determined based on the two models.The optimum processing temperature is 30-45 ℃.展开更多
Co-cured vacuum assisted resin infusion process(co-VARI process),which combined vacuum assisted resin infusion(VARI)with prepreg vacuum bag only process(VBO),was adopted to fabricate T-shaped stiffened skin with non-c...Co-cured vacuum assisted resin infusion process(co-VARI process),which combined vacuum assisted resin infusion(VARI)with prepreg vacuum bag only process(VBO),was adopted to fabricate T-shaped stiffened skin with non-crimp fabric(NCF)stiffener and prepreg skin.During compaction stage of co-VARI process,prepreg resin impregnated fiber fabric under elevated temperature and vacuum pressure.This phenomenon was characterized by fluorescent micrographs with different holding temperature and time.Its influences on processing quality and mechanical performance for co-VARI stiffened skin with different filler materials at triangular region were further analyzed by optical micrographs and pull-off test,respectively.The results show that increasing holding temperature and prolonging holding time can promote prepreg resin impregnation in fiber fabric.Moderate prepreg resin impregnation is favorable to reduce resin rich region and increase fiber volume fraction at prepreg-fabric interface.Moreover,prepreg resin impregnation effect plays significant roles on pull-off performance for co-VARI stiffened skin with fabric filler but has negligible influences on specimens with prepreg filler.In addition,compared with stiffened skin with fabric filler,superior processing quality and pull-off performances are achieved for co-VARI stiffened skin with prepreg core filler.These results are helpful to optimize processing procedures and fabricate composite structure by coVARI process.展开更多
BACKGROUND Surgical resection and liver transplantation(LT)are the most effective curative options for hepatocellular carcinoma(HCC).However,few patients with huge HCC(>10 cm in diameter),especially those with port...BACKGROUND Surgical resection and liver transplantation(LT)are the most effective curative options for hepatocellular carcinoma(HCC).However,few patients with huge HCC(>10 cm in diameter),especially those with portal vein tumor thrombus(PVTT),can receive these treatments.Selective internal radiation therapy(SIRT)can be used as a conversion therapy for them because it has the dual benefit of shrinking tumors and increasing residual hepatic volume.However,in patients with huge HCC,high lung absorbed dose often prevents them from receiving SIRT.CASE SUMMARY A 35-year-old man was admitted because of emaciation and pain in the hepatic region for about 1 month.The computed tomography scan showed a 20.2 cm×19.8 cm tumor located in the right lobe–left medial lobes with right portal vein and right hepatic vein invasion.After the pathological type of HCC was confirmed by biopsy,two conversions were presented.The first one was drug-eluting bead transarterial chemoembolization plus hepatic arterial infusion chemotherapy and lenvatinib and sintilimab,converted to SIRT,and the second one was sequential SIRT with continued systemic treatment.The tumor size significantly decreased from 20.2 cm×19.8 cm to 16.2 cm×13.8 cm,then sequentially to 7.8 cm×6.8 cm.In the meantime,the ratio of spared volume to total liver volume increased gradually from 34.4%to 55.7%,then to 62.9%.Furthermore,there was visualization of the portal vein,indicating regression of the tumor thrombus.Finally,owing to the new tumor in the left lateral lobe,the patient underwent LT instead of resection without major complications.CONCLUSION Patients with inoperable huge HCC with PVTT could be converted to SIRT first and accept surgery sequentially.展开更多
This study proposes a facile, but precise method to back-calculate the effective modulus of nanocomposite interleaving plies. Adaptation of a conventional dry-reinforcement resin film infusion (RFI) approach allows in...This study proposes a facile, but precise method to back-calculate the effective modulus of nanocomposite interleaving plies. Adaptation of a conventional dry-reinforcement resin film infusion (RFI) approach allows interleaving neat epoxy layers (NE) with the epoxy-infused nanofibrous plies (XE) of constant thickness. The final cured nanocomposite laminate thus has the form (NE/XE)n, where “n” denotes the number of the repeats and enables clear distinction of the nanocomposite interlayers through the thickness. Mechanical testing of neat epoxy and laminated nanocomposite specimens can be coupled with the classical lamination theory for back-calculating in-plane elastic modulus of the individual epoxy-infused nanofibrous plies (EXE). Finite element analysis (FEA) and testing the laminated nanocomposite subject to flexural loading (3-point bending) are proposed to validate the analytically back-calculated EXE. It is shown that the FEA prediction incorporating EXE and testing for flexural modulus of (NE/XE)20 laminated nanocomposites correlate well and the results are within 5%. This finding suggests that the back-calculation scheme reported herein would be attractive for accurately determining the properties of an individual nanocomposite building block layer. The proposed framework is beneficial for modelling laminated structural composites incorporating XE-like nanocomposite interlayers.展开更多
据RFI工艺用环氧树脂基树脂膜低温成膜性、高温流动性和浸渗性的技术性能要求,设计了在一定温度内具有低反应活性的GY6010型高粘度液态双酚A二缩水甘油醚环氧树脂、HT907型六氢邻苯二甲酸酐和DY062型苄基二甲胺树脂膜制备体系。根据等...据RFI工艺用环氧树脂基树脂膜低温成膜性、高温流动性和浸渗性的技术性能要求,设计了在一定温度内具有低反应活性的GY6010型高粘度液态双酚A二缩水甘油醚环氧树脂、HT907型六氢邻苯二甲酸酐和DY062型苄基二甲胺树脂膜制备体系。根据等当量反应计算理论和浇注体的力学性能,确定了树脂膜制备体系的最佳混合比例,利用加热聚合、流延成膜和快速冷却方法,制备了具有低固化度的BS-1型环氧树脂基树脂膜。经测试该树脂膜成膜性、弯曲性良好;在80℃的融渗温度下粘度为645 mPa.s,低粘度区域宽度(粘度小于1 000 mPa.s)达25 m in,凝胶时间达56 m in。采用该树脂膜制备的RFI叠层板试件空隙含量(0.8%)极低,与模压试件相比,RFI试件拉伸强度、弯曲强度和层间剪切强度分别提高4.57%、6.26%和21.88%。展开更多
基金Funded bythe National Natural Science Foundation of China(No50573060)
文摘A physically accurate and computationally effective pure finite element method （FEM） was developed to simulate the isothermal resin infusing process. The FEM was based on conservation of resin muss at and instant of time and was objective of resin film infusion （RFI） fiber impregnation and mold filling . The developed computer code was able to simulate the resin infusing visually. A numerical example presented here demonstrated that compared with traditional finite element/ control-volume （FE/CV）, and FEM was physically accurate and computationally efficient.
文摘The most common process to manufacture advanced composites is the costly autoclave.One of the out-of-autoclave alternatives is the low-cost vacuum assisted resin infusion(VARI)which produces quality parts with less pollution.Epoxy resin is a widely used composite matrix resin,but its high flammability limits its use as interior composite parts for vehicles.The usual flame retardant for epoxy involves halogen,which is effective but has high smoke toxicity.As a result,halogen-free flame retardant epoxy resin systems become dominant.In this paper,phosphorus flame retardant was combined with benzoxazine(BOZ)to produce synergistic effect and achieve satisfactory flame retardance,as well as mechanical improvement for the epoxy resin.Differential scanning calorimetry(DSC),dynamic mechanical analysis(DMA),thermal gravitational analysis(TGA),the cone calorimeter(CC),and limiting oxygen index(LOI)were used to characterize the resins.The results showed significant improvement on the flame retardance of the synergistically modified resins.Specifically,the carbon residue increased by 113.6%,and the char thickness increased by 6 to 7 times,compared to those of the flammable benchmark resin.The LOI reached 33 and passed the UL94 V-0 vertical burn rating.The modified resins also exhibited adequate stability and viscosity suitable for VARI processes.
基金The Fundamental Research Funds for the Central Universities,China(No.2232014D3-26)Innovation Fund of the Chinese National Engineering Research Center,China(No.SAM C14-JS-15-049)Science and Technology Commission of Shanghai Municipality,China(No.14DZ1100402)
文摘An experimental procedure was designed to monitor the preform thickness change real-time throughout the vacuum assisted resin infusion( VARI) process. Two kinds of liquid with different viscosity were infused with different post-filling time. The variation of the part thickness during the VARI process was studied. And the effect of the post-filling time on the part thickness was investigated.The results indicate that the compaction behavior of the preform can be divided into three stages,and the fiber volume fraction varies with the post-filling time in a similar sinusoid form. In addition,the post-filling should be overtime for the greatest fiber volume fraction,and when the resin is infused with higher viscosity,the greatest fiber volume fraction is higher.
基金Supported by the 863 National Project of China (No.2007AA03Z563)the Specialized Project of the HUNAN Province of China(No.2006GK1002)
文摘The chemorheological behaviors of a low viscosity epoxy resin system （Huntsman 1564/3486） for vacuum infusion moulding process （VIMP） were studied with viscosity experiments.The dual-Arrhenius rheological model and the engineering viscosity model were established and compared with the experimental data.The result showed that the viscosity in the earlier stage calculated by dual-Arrhenius model were smaller than the experimental data,while the data calculated by the engineering model were larger.Combining the two models together can predict the rheological behaviors of the resin system in a more credible manner.The processing windows of the resin system for VIMP were determined based on the two models.The optimum processing temperature is 30-45 ℃.
文摘Co-cured vacuum assisted resin infusion process(co-VARI process),which combined vacuum assisted resin infusion(VARI)with prepreg vacuum bag only process(VBO),was adopted to fabricate T-shaped stiffened skin with non-crimp fabric(NCF)stiffener and prepreg skin.During compaction stage of co-VARI process,prepreg resin impregnated fiber fabric under elevated temperature and vacuum pressure.This phenomenon was characterized by fluorescent micrographs with different holding temperature and time.Its influences on processing quality and mechanical performance for co-VARI stiffened skin with different filler materials at triangular region were further analyzed by optical micrographs and pull-off test,respectively.The results show that increasing holding temperature and prolonging holding time can promote prepreg resin impregnation in fiber fabric.Moderate prepreg resin impregnation is favorable to reduce resin rich region and increase fiber volume fraction at prepreg-fabric interface.Moreover,prepreg resin impregnation effect plays significant roles on pull-off performance for co-VARI stiffened skin with fabric filler but has negligible influences on specimens with prepreg filler.In addition,compared with stiffened skin with fabric filler,superior processing quality and pull-off performances are achieved for co-VARI stiffened skin with prepreg core filler.These results are helpful to optimize processing procedures and fabricate composite structure by coVARI process.
文摘BACKGROUND Surgical resection and liver transplantation(LT)are the most effective curative options for hepatocellular carcinoma(HCC).However,few patients with huge HCC(>10 cm in diameter),especially those with portal vein tumor thrombus(PVTT),can receive these treatments.Selective internal radiation therapy(SIRT)can be used as a conversion therapy for them because it has the dual benefit of shrinking tumors and increasing residual hepatic volume.However,in patients with huge HCC,high lung absorbed dose often prevents them from receiving SIRT.CASE SUMMARY A 35-year-old man was admitted because of emaciation and pain in the hepatic region for about 1 month.The computed tomography scan showed a 20.2 cm×19.8 cm tumor located in the right lobe–left medial lobes with right portal vein and right hepatic vein invasion.After the pathological type of HCC was confirmed by biopsy,two conversions were presented.The first one was drug-eluting bead transarterial chemoembolization plus hepatic arterial infusion chemotherapy and lenvatinib and sintilimab,converted to SIRT,and the second one was sequential SIRT with continued systemic treatment.The tumor size significantly decreased from 20.2 cm×19.8 cm to 16.2 cm×13.8 cm,then sequentially to 7.8 cm×6.8 cm.In the meantime,the ratio of spared volume to total liver volume increased gradually from 34.4%to 55.7%,then to 62.9%.Furthermore,there was visualization of the portal vein,indicating regression of the tumor thrombus.Finally,owing to the new tumor in the left lateral lobe,the patient underwent LT instead of resection without major complications.CONCLUSION Patients with inoperable huge HCC with PVTT could be converted to SIRT first and accept surgery sequentially.
文摘This study proposes a facile, but precise method to back-calculate the effective modulus of nanocomposite interleaving plies. Adaptation of a conventional dry-reinforcement resin film infusion (RFI) approach allows interleaving neat epoxy layers (NE) with the epoxy-infused nanofibrous plies (XE) of constant thickness. The final cured nanocomposite laminate thus has the form (NE/XE)n, where “n” denotes the number of the repeats and enables clear distinction of the nanocomposite interlayers through the thickness. Mechanical testing of neat epoxy and laminated nanocomposite specimens can be coupled with the classical lamination theory for back-calculating in-plane elastic modulus of the individual epoxy-infused nanofibrous plies (EXE). Finite element analysis (FEA) and testing the laminated nanocomposite subject to flexural loading (3-point bending) are proposed to validate the analytically back-calculated EXE. It is shown that the FEA prediction incorporating EXE and testing for flexural modulus of (NE/XE)20 laminated nanocomposites correlate well and the results are within 5%. This finding suggests that the back-calculation scheme reported herein would be attractive for accurately determining the properties of an individual nanocomposite building block layer. The proposed framework is beneficial for modelling laminated structural composites incorporating XE-like nanocomposite interlayers.
文摘据RFI工艺用环氧树脂基树脂膜低温成膜性、高温流动性和浸渗性的技术性能要求,设计了在一定温度内具有低反应活性的GY6010型高粘度液态双酚A二缩水甘油醚环氧树脂、HT907型六氢邻苯二甲酸酐和DY062型苄基二甲胺树脂膜制备体系。根据等当量反应计算理论和浇注体的力学性能,确定了树脂膜制备体系的最佳混合比例,利用加热聚合、流延成膜和快速冷却方法,制备了具有低固化度的BS-1型环氧树脂基树脂膜。经测试该树脂膜成膜性、弯曲性良好;在80℃的融渗温度下粘度为645 mPa.s,低粘度区域宽度(粘度小于1 000 mPa.s)达25 m in,凝胶时间达56 m in。采用该树脂膜制备的RFI叠层板试件空隙含量(0.8%)极低,与模压试件相比,RFI试件拉伸强度、弯曲强度和层间剪切强度分别提高4.57%、6.26%和21.88%。
