The Experts below are selected from a list of 2763 Experts worldwide ranked by ideXlab platform

Xinglong Gong - One of the best experts on this subject based on the ideXlab platform.

  • cnt stf kevlar based wearable electronic textile with excellent anti impact and sensing performance
    Composites Part A-applied Science and Manufacturing, 2019
    Co-Authors: Mei Liu, Saisai Cao, Shouhu Xuan, Wanquan Jiang, Shuaishuai Zhang, Shuai Liu, Sheng Wang, Linfeng Bai, Min Sang, Xinglong Gong
    Abstract:

    Abstract This work reports a novel CNT/STF/Kevlar-based (CNT, carbon nanotubes; STF, Shear Thickening Fluid) wearable electronic textile (ET) composite with excellent protective and sensing performance. The dynamic impact resistance test shows the maximum resistance force of the single-layer ET composite reaches as high as 1232 N, which is much larger than the neat Kevlar (746 N), indicating that the ET composite can absorb more energy and sustain higher impact force. Due to the incorporation of the carbon nanotubes (CNTs), the ET composite shows excellent conductivity, thus it can be applied as a sensor to monitor signals of various human body movements. Due to the good flexibility, high sensitivity, and excellent protective performance, the ET composite exhibits high potential in the intelligent wearable electronic textile product, which possesses both excellent protective and sensing performance for human bodies in different environments.

  • impact resistance of Shear Thickening Fluid kevlar composite treated with Shear stiffening gel
    Composites Part A-applied Science and Manufacturing, 2018
    Co-Authors: Qianyun He, Shouhu Xuan, Yunpeng Wang, Pengfei Wang, Xinglong Gong
    Abstract:

    Abstract In this work, Shear-stiffening gel (STG) was introduced into Shear Thickening Fluid (STF)-impregnated-Kevlar® woven fabric (Kevlar/STF) to improve the impact resistance. The STF filled within the yarns of Kevlar and the STG covered the Kevlar/STF to form Kevlar/STF/STG composite. The STG in the Kevlar/STF/STG not only protected STF but also improved the impact resistance of the fabric because of its excellent Shear-stiffening characteristics. A series of experiments including the yarn pull-out test, the split Hopkinson pressure bar impact test, rod penetration test, and knife cutting test were carried out to verify the enhancement effect. The improvement mechanism of the impact resistance for the Kevlar/STF/STG was studied. Under the similar anti-impact performance, the Kevlar/STF/STG possessed lower weight than the Kevlar and its strong impact resistance originated from the synergetic effect among the STF, STG and Kevlar. Therefore, the Kevlar/STF/STG exhibited broad potential in the soft body armor.

  • high strain rate dynamic mechanical properties of kevlar fabrics impregnated with Shear Thickening Fluid
    Composites Part A-applied Science and Manufacturing, 2017
    Co-Authors: Qian Chen, Shouhu Xuan, Wanquan Jiang, Yunpeng Wang, Xinglong Gong
    Abstract:

    Abstract To investigate the anti-impact mechanism, the mechanical property and energy absorption of the STF impregnated Kevlar (STF/Kevlar) fabric at high strain rate were conducted using a split Hopkinson pressure bar (SHPB) system. The volume fraction of STF, number of fabric specimens, and impact velocity highly affected the dynamic mechanical performance of the STF/Kevlar composite. The energy transfer rate decreased from 0.85 to 0.01 once the number of fabric specimens increased from 2 layers to 8 layers. The strain rate stiffening mechanism of the STF/Kevlar was analyzed. The Kevlar fabrics underwent four sections during the impact process. The STF was mainly worked in the slip and deformation section by enhancing the friction between fabric yarns and preventing the fabric yarns from slipping. Overall, this work demonstrated that the multilayer Kevlar fabrics impregnated with high volume fraction of STF were the optimal choice for soft body armor.

  • a facile one step method to synthesize sio2 polydopamine core shell nanospheres for Shear Thickening Fluid
    RSC Advances, 2016
    Co-Authors: Mei Liu, Wanquan Jiang, Qian Chen, Xinglong Gong, Sheng Wang, Ya Mao, Ken Chamfai Leung, Jie Tian, Huijuan Wang, Shouhu Xuan
    Abstract:

    A facile one-step method was developed to synthesize core–shell structured SiO2@polydopamine (PDA) nanospheres. During the synthesis, a PDA shell was simultaneously coated on the SiO2 nanospheres to form the core–shell nanostructure. The PDA shell thickness was tunable by varying the concentration of the starting dopamine precursor. After dispersing the core–shell nanospheres into poly(ethylene glycol) 200 (PEG200), a SiO2@PDA based Shear Thickening Fluid (STF) was obtained. In comparison to pristine SiO2, the SiO2@PDA based STF presented better ST effects and its maximum viscosity could reach as high as 194.6 Pa s. A possible enhancement mechanism was proposed in order to investigate the structural dependence of the ST effect. This high performance SiO2@PDA based STF could be widely applied in body armor and other safe-guarding areas.

  • Shear time dependent viscosity of polystyrene ethylacrylate based Shear Thickening Fluid
    Smart Materials and Structures, 2016
    Co-Authors: Qian Chen, Saisai Cao, Shouhu Xuan, Wanquan Jiang, Xinglong Gong
    Abstract:

    In this study, the influence of the Shear rate and Shear time on the transient viscosity of polystyrene-ethylacrylate based Shear Thickening Fluid (STF) is investigated. If the Shear rate is stepwise changed, it is found that both the viscosity and critical Shear rate are affected by the Shear time. Above the critical Shear rate, the viscosity of the STF with larger power law exponent (n) increases faster. However, the viscosity tends to decrease when the Shear time is long enough. This phenomenon can be responsible for the reversible structure buildup and the break-down process. An effective volume fraction (EVF) mechanism is proposed to analyze the Shear time dependent viscosity and it is found that viscosity changes in proportion to EVF. To further clarify the structure evolution, a structural kinetic model is studied because the structural kinetic parameter (λ) could describe the variation in the effective volume fraction. The theoretical results of the structural kinetic model agree well with the experimental results. With this model, the change in viscosity and EVF can be speculated from the variation of λ and then the structure evolution can be better illustrated.

Abhijit Majumdar - One of the best experts on this subject based on the ideXlab platform.

  • deconstructing the role of Shear Thickening Fluid in enhancing the impact resistance of high performance fabrics
    Composites Part B-engineering, 2019
    Co-Authors: Unsanhame Mawkhlieng, Abhijit Majumdar
    Abstract:

    Abstract The role of Shear Thickening Fluid (STF) in enhancing the impact resistance of STF treated fabrics has long been debated. There is a need to clarify whether the dominant mechanism of energy absorption is Shear Thickening (dilatancy) or friction enhancement. This study establishes that the inherent Shear Thickening behaviour of STF has a decisive role to play other than just improving the yarn to yarn friction. Kevlar® 363 and Kevlar® 802 F fabrics were treated with STF comprising of 65% (w/w) silica and 35% polyethylene glycol (PEG) 200. Three monodispersed STFs and nine bi-dispersed STFs were prepared from three different particle sizes of silica (100 nm, 300 nm and 500 nm) and their binary mixtures keeping the mass fraction of silica constant (65%). Rheological results showed that STFs prepared form monodispersed silica resulted in higher peak viscosity as well as discontinuous Shear Thickening. However, bi-dispersed STFs prepared by mixing two different sizes of silica particles, in general, showed lower peak viscosity and continuous Shear Thickening. In both the fabrics (Kevlar® 363 and Kevlar® 802 F), yarn pull-out force, a measure of yarn to yarn friction, did not show much difference among the fabrics treated with different STFs. However, low velocity impact tests clearly showed enhanced performance in terms of energy absorption and peak force in case of fabrics treated with monodispersed STFs. This correlation between Shear Thickening and impact resistance conclusively establishes that the former has a dominant role in enhancing the latter of high-performance fabrics.

  • structure induced effectiveness of Shear Thickening Fluid for modulating impact resistance of uhmwpe fabrics
    Composite Structures, 2019
    Co-Authors: Sanchi Arora, Abhijit Majumdar, Bhupendra Singh Butola
    Abstract:

    Abstract The structural parameters of woven fabrics play a crucial role in determining its impact resistance performance. Conventionally, treatment with Shear Thickening Fluid (STF) has been found to increase the impact energy absorption capacity of fabrics. However, the findings of the current study present a new perspective, and suggest that the effect of STF treatment is favorable based on the structural integrity of woven fabrics. Plain woven fabrics with different fabric sett (threads per inch) were produced using ultra-high molecular weight polyethylene (UHMWPE) yarns of 400 denier and 1350 denier linear density. These fabrics were then treated with STF (65% w/w) made from silica particles (100 nm) dispersed in polyethylene glycol i.e. PEG (200 Mw) and subsequently evaluated for yarn pull-out force and impact energy absorption. The increased yarn pull-out force, at all levels of yarn linear density and fabric sett, implies that STF treatment considerably increases the inter-yarn friction. However, increased yarn to yarn friction is not necessarily beneficial in terms of impact energy absorption and rather becomes detrimental for fabrics made from finer yarns (400 denier) beyond a particular fabric sett.

  • interactive effects of p aramid fabric structure and Shear Thickening Fluid on impact resistance performance of soft armor materials
    Materials & Design, 2016
    Co-Authors: Animesh Laha, Abhijit Majumdar
    Abstract:

    Abstract Soft body armors are generally made with fabrics woven from high performance yarns. Impact resistance of woven fabrics mostly depends upon fiber type, weave and thread density. Of late, woven fabrics made from high performance yarns are being impregnated with Shear Thickening Fluids (STFs) to enhance their impact resistance. In this research, five different weave structures were prepared with varying thread densities of p-aramid (Technora) yarns, followed by treatment with 60% w/w STF to develop soft armor materials. Untreated and STF treated Technora fabrics were evaluated for energy absorption using dynamic impact resistance tester. In untreated condition, plain woven fabrics showed the highest impact resistance, followed by 3/1 twill, 2/2 twill, 5 end satin and 2/2 matt. STF treatment improved the impact resistance performance in all the weave structures and thread densities except for the plain weave with the highest thread density. The ascending order of weaves in terms of enhancement in impact energy absorption after STF treatment was exactly opposite to the ascending order of weaves in terms of impact energy absorption before STF treatment.

  • development of soft composite materials with improved impact resistance using kevlar fabric and nano silica based Shear Thickening Fluid
    Materials & Design, 2014
    Co-Authors: Abhijit Majumdar, Bhupendra Singh Butola, Ankita Srivastava
    Abstract:

    Abstract The application of Shear Thickening Fluid (STF) on Kevlar fabrics improves the impact energy absorption by the soft composite as the viscosity of the former increases drastically during impact. The influence of process parameters like padding (squeezing) pressure and silica concentration in STF on impact performance of Kevlar–STF soft composite has been investigated in this research. The impact energy has been measured by dynamic impact tester as well as by low speed bullet impact test using a 0.380 Caliber revolver. Higher STF concentration improves the impact energy absorption by the Kevlar–STF soft composite. Higher padding pressure reduces the STF add-on% on Kevlar fabrics making the composite lighter. However, the impact energy absorption by the Kevlar–STF composite increases with the increase in padding pressure due to better and uniform distribution of STF within the fabric and yarn structures. The beneficial effect of higher padding pressure on impact energy absorption was also verified by the low velocity bullet impact test. At optimum process conditions, the impact energy absorption by Kevlar–STF soft composite goes up by around 150% and 400%, depending on the type of Kevlar fabric.

  • an analysis of deformation and energy absorption modes of Shear Thickening Fluid treated kevlar fabrics as soft body armour materials
    Materials & Design, 2013
    Co-Authors: Abhijit Majumdar, Bhupendra Singh Butola, Ankita Srivastava
    Abstract:

    In this article the deformation and energy absorption modes of Shear Thickening Fluid (STF) treated and untreated Kevlar woven fabrics upon impact has been presented. It was found that in untreated Kevlar fabrics, only the primary yarns, which are engaged by the impactor, participate in load sharing and hence energy absorption. Since the load per yarn is high, the yarns slip at the grip, forming long loops but the rest of the fabric remains undisturbed. Due to participation of only a few yarns, the energy absorption is low. However, in case of STF treated fabrics, the STF is transformed into a solid like material during impact. The transformed STF acts as a bridging matrix which converts the network of yarns in the fabric into a single structure. Hence, unlike in untreated fabrics, the entire fabric rather than only primary yarns participates in load bearing and energy absorption. The failure of the STF treated structure is by rupture of fibers and yarns rather than their slippage.

Bhupendra Singh Butola - One of the best experts on this subject based on the ideXlab platform.

  • structure induced effectiveness of Shear Thickening Fluid for modulating impact resistance of uhmwpe fabrics
    Composite Structures, 2019
    Co-Authors: Sanchi Arora, Abhijit Majumdar, Bhupendra Singh Butola
    Abstract:

    Abstract The structural parameters of woven fabrics play a crucial role in determining its impact resistance performance. Conventionally, treatment with Shear Thickening Fluid (STF) has been found to increase the impact energy absorption capacity of fabrics. However, the findings of the current study present a new perspective, and suggest that the effect of STF treatment is favorable based on the structural integrity of woven fabrics. Plain woven fabrics with different fabric sett (threads per inch) were produced using ultra-high molecular weight polyethylene (UHMWPE) yarns of 400 denier and 1350 denier linear density. These fabrics were then treated with STF (65% w/w) made from silica particles (100 nm) dispersed in polyethylene glycol i.e. PEG (200 Mw) and subsequently evaluated for yarn pull-out force and impact energy absorption. The increased yarn pull-out force, at all levels of yarn linear density and fabric sett, implies that STF treatment considerably increases the inter-yarn friction. However, increased yarn to yarn friction is not necessarily beneficial in terms of impact energy absorption and rather becomes detrimental for fabrics made from finer yarns (400 denier) beyond a particular fabric sett.

  • development of soft composite materials with improved impact resistance using kevlar fabric and nano silica based Shear Thickening Fluid
    Materials & Design, 2014
    Co-Authors: Abhijit Majumdar, Bhupendra Singh Butola, Ankita Srivastava
    Abstract:

    Abstract The application of Shear Thickening Fluid (STF) on Kevlar fabrics improves the impact energy absorption by the soft composite as the viscosity of the former increases drastically during impact. The influence of process parameters like padding (squeezing) pressure and silica concentration in STF on impact performance of Kevlar–STF soft composite has been investigated in this research. The impact energy has been measured by dynamic impact tester as well as by low speed bullet impact test using a 0.380 Caliber revolver. Higher STF concentration improves the impact energy absorption by the Kevlar–STF soft composite. Higher padding pressure reduces the STF add-on% on Kevlar fabrics making the composite lighter. However, the impact energy absorption by the Kevlar–STF composite increases with the increase in padding pressure due to better and uniform distribution of STF within the fabric and yarn structures. The beneficial effect of higher padding pressure on impact energy absorption was also verified by the low velocity bullet impact test. At optimum process conditions, the impact energy absorption by Kevlar–STF soft composite goes up by around 150% and 400%, depending on the type of Kevlar fabric.

  • an analysis of deformation and energy absorption modes of Shear Thickening Fluid treated kevlar fabrics as soft body armour materials
    Materials & Design, 2013
    Co-Authors: Abhijit Majumdar, Bhupendra Singh Butola, Ankita Srivastava
    Abstract:

    In this article the deformation and energy absorption modes of Shear Thickening Fluid (STF) treated and untreated Kevlar woven fabrics upon impact has been presented. It was found that in untreated Kevlar fabrics, only the primary yarns, which are engaged by the impactor, participate in load sharing and hence energy absorption. Since the load per yarn is high, the yarns slip at the grip, forming long loops but the rest of the fabric remains undisturbed. Due to participation of only a few yarns, the energy absorption is low. However, in case of STF treated fabrics, the STF is transformed into a solid like material during impact. The transformed STF acts as a bridging matrix which converts the network of yarns in the fabric into a single structure. Hence, unlike in untreated fabrics, the entire fabric rather than only primary yarns participates in load bearing and energy absorption. The failure of the STF treated structure is by rupture of fibers and yarns rather than their slippage.

  • optimal designing of soft body armour materials using Shear Thickening Fluid
    Materials & Design, 2013
    Co-Authors: Abhijit Majumdar, Bhupendra Singh Butola, Ankita Srivastava
    Abstract:

    This paper deals with the optimal design of soft body armour materials by treating Kevlar (para-aramid) fabrics with silica nano-particle based Shear Thickening Fluid (STF). Box and Behnken design of experiment (DOE) plan in conjunction with contour analysis has been used to study the effect of silica concentration, padding pressure and diluent: STF ratio (solvent ratio) on STF add-on% and impact energy absorption. Silica concentration, solvent ratio and square of solvent ratio were found to be statistically significant terms influencing the STF add-on% on Kevlar fabrics. On the other hand, silica concentration, padding pressure and the square of solvent ratio were the statistically significant terms influencing the impact energy absorption. Higher padding pressure enhances the impact energy absorption by the STF treated Kevlar fabrics although it does not influence the STF add-on% significantly. Higher STF add-on% is a necessary but not the sufficient condition for improving the impact resistance performance of Kevlar fabrics.

  • improving the impact resistance performance of kevlar fabrics using silica based Shear Thickening Fluid
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2011
    Co-Authors: Ankita Srivastava, Abhijit Majumdar, Bhupendra Singh Butola
    Abstract:

    Abstract Impact energy absorption capacity of Kevlar woven fabrics has been improved using silica particle based Shear Thickening Fluid (STF). The influence of padding pressure and silica concentration in STF on add-on%, yarn pull out force and impact energy absorption has been studied. Higher padding pressure reduces the STF add-on%, but increases the impact energy absorption. Therefore, it is possible to achieve enhanced impact energy absorption performance at lower STF add-on%, i.e. lower fabric weight. It is also understood that the yarn to yarn friction, as measured by the quasi-static yarn pull-out force, only partially influences the impact performance of STF treated Kevlar woven fabrics.

Ankita Srivastava - One of the best experts on this subject based on the ideXlab platform.

  • development of soft composite materials with improved impact resistance using kevlar fabric and nano silica based Shear Thickening Fluid
    Materials & Design, 2014
    Co-Authors: Abhijit Majumdar, Bhupendra Singh Butola, Ankita Srivastava
    Abstract:

    Abstract The application of Shear Thickening Fluid (STF) on Kevlar fabrics improves the impact energy absorption by the soft composite as the viscosity of the former increases drastically during impact. The influence of process parameters like padding (squeezing) pressure and silica concentration in STF on impact performance of Kevlar–STF soft composite has been investigated in this research. The impact energy has been measured by dynamic impact tester as well as by low speed bullet impact test using a 0.380 Caliber revolver. Higher STF concentration improves the impact energy absorption by the Kevlar–STF soft composite. Higher padding pressure reduces the STF add-on% on Kevlar fabrics making the composite lighter. However, the impact energy absorption by the Kevlar–STF composite increases with the increase in padding pressure due to better and uniform distribution of STF within the fabric and yarn structures. The beneficial effect of higher padding pressure on impact energy absorption was also verified by the low velocity bullet impact test. At optimum process conditions, the impact energy absorption by Kevlar–STF soft composite goes up by around 150% and 400%, depending on the type of Kevlar fabric.

  • an analysis of deformation and energy absorption modes of Shear Thickening Fluid treated kevlar fabrics as soft body armour materials
    Materials & Design, 2013
    Co-Authors: Abhijit Majumdar, Bhupendra Singh Butola, Ankita Srivastava
    Abstract:

    In this article the deformation and energy absorption modes of Shear Thickening Fluid (STF) treated and untreated Kevlar woven fabrics upon impact has been presented. It was found that in untreated Kevlar fabrics, only the primary yarns, which are engaged by the impactor, participate in load sharing and hence energy absorption. Since the load per yarn is high, the yarns slip at the grip, forming long loops but the rest of the fabric remains undisturbed. Due to participation of only a few yarns, the energy absorption is low. However, in case of STF treated fabrics, the STF is transformed into a solid like material during impact. The transformed STF acts as a bridging matrix which converts the network of yarns in the fabric into a single structure. Hence, unlike in untreated fabrics, the entire fabric rather than only primary yarns participates in load bearing and energy absorption. The failure of the STF treated structure is by rupture of fibers and yarns rather than their slippage.

  • optimal designing of soft body armour materials using Shear Thickening Fluid
    Materials & Design, 2013
    Co-Authors: Abhijit Majumdar, Bhupendra Singh Butola, Ankita Srivastava
    Abstract:

    This paper deals with the optimal design of soft body armour materials by treating Kevlar (para-aramid) fabrics with silica nano-particle based Shear Thickening Fluid (STF). Box and Behnken design of experiment (DOE) plan in conjunction with contour analysis has been used to study the effect of silica concentration, padding pressure and diluent: STF ratio (solvent ratio) on STF add-on% and impact energy absorption. Silica concentration, solvent ratio and square of solvent ratio were found to be statistically significant terms influencing the STF add-on% on Kevlar fabrics. On the other hand, silica concentration, padding pressure and the square of solvent ratio were the statistically significant terms influencing the impact energy absorption. Higher padding pressure enhances the impact energy absorption by the STF treated Kevlar fabrics although it does not influence the STF add-on% significantly. Higher STF add-on% is a necessary but not the sufficient condition for improving the impact resistance performance of Kevlar fabrics.

  • improving the impact resistance performance of kevlar fabrics using silica based Shear Thickening Fluid
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2011
    Co-Authors: Ankita Srivastava, Abhijit Majumdar, Bhupendra Singh Butola
    Abstract:

    Abstract Impact energy absorption capacity of Kevlar woven fabrics has been improved using silica particle based Shear Thickening Fluid (STF). The influence of padding pressure and silica concentration in STF on add-on%, yarn pull out force and impact energy absorption has been studied. Higher padding pressure reduces the STF add-on%, but increases the impact energy absorption. Therefore, it is possible to achieve enhanced impact energy absorption performance at lower STF add-on%, i.e. lower fabric weight. It is also understood that the yarn to yarn friction, as measured by the quasi-static yarn pull-out force, only partially influences the impact performance of STF treated Kevlar woven fabrics.

Shouhu Xuan - One of the best experts on this subject based on the ideXlab platform.

  • cnt stf kevlar based wearable electronic textile with excellent anti impact and sensing performance
    Composites Part A-applied Science and Manufacturing, 2019
    Co-Authors: Mei Liu, Saisai Cao, Shouhu Xuan, Wanquan Jiang, Shuaishuai Zhang, Shuai Liu, Sheng Wang, Linfeng Bai, Min Sang, Xinglong Gong
    Abstract:

    Abstract This work reports a novel CNT/STF/Kevlar-based (CNT, carbon nanotubes; STF, Shear Thickening Fluid) wearable electronic textile (ET) composite with excellent protective and sensing performance. The dynamic impact resistance test shows the maximum resistance force of the single-layer ET composite reaches as high as 1232 N, which is much larger than the neat Kevlar (746 N), indicating that the ET composite can absorb more energy and sustain higher impact force. Due to the incorporation of the carbon nanotubes (CNTs), the ET composite shows excellent conductivity, thus it can be applied as a sensor to monitor signals of various human body movements. Due to the good flexibility, high sensitivity, and excellent protective performance, the ET composite exhibits high potential in the intelligent wearable electronic textile product, which possesses both excellent protective and sensing performance for human bodies in different environments.

  • impact resistance of Shear Thickening Fluid kevlar composite treated with Shear stiffening gel
    Composites Part A-applied Science and Manufacturing, 2018
    Co-Authors: Qianyun He, Shouhu Xuan, Yunpeng Wang, Pengfei Wang, Xinglong Gong
    Abstract:

    Abstract In this work, Shear-stiffening gel (STG) was introduced into Shear Thickening Fluid (STF)-impregnated-Kevlar® woven fabric (Kevlar/STF) to improve the impact resistance. The STF filled within the yarns of Kevlar and the STG covered the Kevlar/STF to form Kevlar/STF/STG composite. The STG in the Kevlar/STF/STG not only protected STF but also improved the impact resistance of the fabric because of its excellent Shear-stiffening characteristics. A series of experiments including the yarn pull-out test, the split Hopkinson pressure bar impact test, rod penetration test, and knife cutting test were carried out to verify the enhancement effect. The improvement mechanism of the impact resistance for the Kevlar/STF/STG was studied. Under the similar anti-impact performance, the Kevlar/STF/STG possessed lower weight than the Kevlar and its strong impact resistance originated from the synergetic effect among the STF, STG and Kevlar. Therefore, the Kevlar/STF/STG exhibited broad potential in the soft body armor.

  • high strain rate dynamic mechanical properties of kevlar fabrics impregnated with Shear Thickening Fluid
    Composites Part A-applied Science and Manufacturing, 2017
    Co-Authors: Qian Chen, Shouhu Xuan, Wanquan Jiang, Yunpeng Wang, Xinglong Gong
    Abstract:

    Abstract To investigate the anti-impact mechanism, the mechanical property and energy absorption of the STF impregnated Kevlar (STF/Kevlar) fabric at high strain rate were conducted using a split Hopkinson pressure bar (SHPB) system. The volume fraction of STF, number of fabric specimens, and impact velocity highly affected the dynamic mechanical performance of the STF/Kevlar composite. The energy transfer rate decreased from 0.85 to 0.01 once the number of fabric specimens increased from 2 layers to 8 layers. The strain rate stiffening mechanism of the STF/Kevlar was analyzed. The Kevlar fabrics underwent four sections during the impact process. The STF was mainly worked in the slip and deformation section by enhancing the friction between fabric yarns and preventing the fabric yarns from slipping. Overall, this work demonstrated that the multilayer Kevlar fabrics impregnated with high volume fraction of STF were the optimal choice for soft body armor.

  • a facile one step method to synthesize sio2 polydopamine core shell nanospheres for Shear Thickening Fluid
    RSC Advances, 2016
    Co-Authors: Mei Liu, Wanquan Jiang, Qian Chen, Xinglong Gong, Sheng Wang, Ya Mao, Ken Chamfai Leung, Jie Tian, Huijuan Wang, Shouhu Xuan
    Abstract:

    A facile one-step method was developed to synthesize core–shell structured SiO2@polydopamine (PDA) nanospheres. During the synthesis, a PDA shell was simultaneously coated on the SiO2 nanospheres to form the core–shell nanostructure. The PDA shell thickness was tunable by varying the concentration of the starting dopamine precursor. After dispersing the core–shell nanospheres into poly(ethylene glycol) 200 (PEG200), a SiO2@PDA based Shear Thickening Fluid (STF) was obtained. In comparison to pristine SiO2, the SiO2@PDA based STF presented better ST effects and its maximum viscosity could reach as high as 194.6 Pa s. A possible enhancement mechanism was proposed in order to investigate the structural dependence of the ST effect. This high performance SiO2@PDA based STF could be widely applied in body armor and other safe-guarding areas.

  • Shear time dependent viscosity of polystyrene ethylacrylate based Shear Thickening Fluid
    Smart Materials and Structures, 2016
    Co-Authors: Qian Chen, Saisai Cao, Shouhu Xuan, Wanquan Jiang, Xinglong Gong
    Abstract:

    In this study, the influence of the Shear rate and Shear time on the transient viscosity of polystyrene-ethylacrylate based Shear Thickening Fluid (STF) is investigated. If the Shear rate is stepwise changed, it is found that both the viscosity and critical Shear rate are affected by the Shear time. Above the critical Shear rate, the viscosity of the STF with larger power law exponent (n) increases faster. However, the viscosity tends to decrease when the Shear time is long enough. This phenomenon can be responsible for the reversible structure buildup and the break-down process. An effective volume fraction (EVF) mechanism is proposed to analyze the Shear time dependent viscosity and it is found that viscosity changes in proportion to EVF. To further clarify the structure evolution, a structural kinetic model is studied because the structural kinetic parameter (λ) could describe the variation in the effective volume fraction. The theoretical results of the structural kinetic model agree well with the experimental results. With this model, the change in viscosity and EVF can be speculated from the variation of λ and then the structure evolution can be better illustrated.