The penetration resistance of Kevlar-129 fiber reinforced composite materials was investigated with AUTODYN software.The ballistic limits of the fragment that pierced 6kinds of target plates were obtained by finite el...The penetration resistance of Kevlar-129 fiber reinforced composite materials was investigated with AUTODYN software.The ballistic limits of the fragment that pierced 6kinds of target plates were obtained by finite element simulation when the 10 g fragment simulation projectile（FSP）impacting to the target plates of different thickness values of 8,10,12,14,16 and 18mm with appropriate velocity,respectively,and the influences of thickness on the ballistic limits and the specific energy absorption were analyzed.The results show that the ballistic limit of Kevlar-129 fiber reinforced composite plates presents linear growth with the increase of the target thickness in the range from 8to 18 mm.The specific energy absorption of plates presents approximately linear growth,but there is slightly slow growth in the range from 10 to 16mm of the target thickness.It also can be found that the influences of plate thickness and surface density on the varying pattern of specific energy absorption are almost the same.Therefore,both of them can be used to characterize the variation of specific energy absorption under the impact of the FSP fragment.展开更多
The existing research of the woven fabric self-lubricating liner mainly focus on the tribological performance improvements and the service life raised by changing different fiber type combinations, adding additive mod...The existing research of the woven fabric self-lubricating liner mainly focus on the tribological performance improvements and the service life raised by changing different fiber type combinations, adding additive modification, and performing fiber surface modification. As fabric composites, the weave structures play an important role in the mechanical and tribological performances of the liners. However, hardly any literature is available on the friction and wear behavior of such composites with different weave structures. In this paper, three weave structures （plain, twill 1/3 and satin 8/5） of hybrid Kevlar/PTFE fabric composites are selected and pin-on-flat linear reciprocating wear studies are done on a CETR tester under different pressures and different frequencies. The relationship between the tensile strength and the wear performance are studied. The morphologies of the worn surfaces under the typical test conditions are analyzed by means of scanning electron microscopy （SEM）. The analysis results show that at 10 MPa, satin 8/5 performs the best in friction-reduction and antiwear performance, and plain is the worst. At 30 MPa, however, the antiwear performance is reversed and satin 8/5 does not even complete the 2 h wear test at 16 Hz. There is no clear evidence proving that the tensile strength has an influence on the wear performance. So the different tribological performance of the three weave structures of fabric composites may be attributed to the different PTFE proportions in the fabric surface and the different wear mechanisms. The fabric composites are divided into three regions： the lubrication region, the reinforced region and the bonding region. The major mechanisms are fatigue wear and the shear effects of the friction force in the lubrication region. In the reinforced region fiber-matrix de-bonding and fiber breakage are involved. The proposed research proposes a regional wear model and further indicates the wear process and the wear mechanism of fabric composites.展开更多
The Kevlar/polytetrafluroethylene（Kevlar/PTFE） fabric composite can be used as a self-lubricating liner of the self-lubricating bearing.Many types of nano-particles can improve the tribological performance of the po...The Kevlar/polytetrafluroethylene（Kevlar/PTFE） fabric composite can be used as a self-lubricating liner of the self-lubricating bearing.Many types of nano-particles can improve the tribological performance of the polymer-based composite.Unfortunately,up to now,published work on the effect of nano-particles on the tribological performance of the fabric composite which can be used as a self-lubricating liner is quite scarce.Therefore,for the purpose of exploring a way to significantly improve the tribological performance of the fabric composite,the tribological performance of the Kevlar/PTFE fabric composite filled with nano-titania is evaluated by using the block-on-ring wear tester.The scanning electron microscopy is utilized to observe the morphologies of worn surfaces of the fabric composites and the counterparts.The tensile properties of the composites are evaluated on the universal material testing machine.The test results show that the addition of nano-titania at a proper mass fraction of the matrix resin improves the wear resistance and the tensile strength,decreases the friction coefficient,and makes the wear volume of the composite reach a relative steady state more quickly;plastic deformation and microcutting are important for the wear of the fabric composite;a lubricating layer is formed on the worn surface of the composite during sliding,and the lubricating layer is critical for the tribological performance of the composite;the formation and properties of the lubricating layer are influenced by the nano-titania particles.The proposed study on the effect of nano-titania on the tribological performance of the Kevlar/PTFE fabric composite,especially on the evolution of the worn surface of the composite,provides the basis for further understanding of the influence mechanism of the nano-particles on the tribological performance of the composite and explores a method of improving the tribological performance of the composite.展开更多
In this work, the polytetrafluoroethylene (PTFE)-based composite substrates were manufactured by mixing, calendering, hot-pressing sintering. The composition of all the samples was PTFE, SiO2 and chopped E-glass fiber...In this work, the polytetrafluoroethylene (PTFE)-based composite substrates were manufactured by mixing, calendering, hot-pressing sintering. The composition of all the samples was PTFE, SiO2 and chopped E-glass fibers. The effects of content of E-glass fibers on the properties of the SiO2 filled PTFE composites were investigated, including density, water absorption, dielectric properties (εr, tanδ), coefficient of thermal expansion (CTE) and temperature coefficient of dielectric constant (τε). The compositions of inorganic materials mixture are (62 ? x) % SiO2 + x % E-glass fiber (x: mass ratio to composites, x = 0, 1, 1.5, 2, 2.5, 3). The results show that as the content of E-glass fibers is 2.5 wt.%, this composite obtains optimal properties, including excellent dielectric properties (εr^2.9123, tanδ~0.0011), acceptable water absorption of 0.075%, temperature coefficient of dielectric constant of 10 ppm/?C and coefficient of thermal expansion of 15.87 ppm/?C.展开更多
文摘The penetration resistance of Kevlar-129 fiber reinforced composite materials was investigated with AUTODYN software.The ballistic limits of the fragment that pierced 6kinds of target plates were obtained by finite element simulation when the 10 g fragment simulation projectile（FSP）impacting to the target plates of different thickness values of 8,10,12,14,16 and 18mm with appropriate velocity,respectively,and the influences of thickness on the ballistic limits and the specific energy absorption were analyzed.The results show that the ballistic limit of Kevlar-129 fiber reinforced composite plates presents linear growth with the increase of the target thickness in the range from 8to 18 mm.The specific energy absorption of plates presents approximately linear growth,but there is slightly slow growth in the range from 10 to 16mm of the target thickness.It also can be found that the influences of plate thickness and surface density on the varying pattern of specific energy absorption are almost the same.Therefore,both of them can be used to characterize the variation of specific energy absorption under the impact of the FSP fragment.
基金supported by National Defense Foundation of China
文摘The existing research of the woven fabric self-lubricating liner mainly focus on the tribological performance improvements and the service life raised by changing different fiber type combinations, adding additive modification, and performing fiber surface modification. As fabric composites, the weave structures play an important role in the mechanical and tribological performances of the liners. However, hardly any literature is available on the friction and wear behavior of such composites with different weave structures. In this paper, three weave structures （plain, twill 1/3 and satin 8/5） of hybrid Kevlar/PTFE fabric composites are selected and pin-on-flat linear reciprocating wear studies are done on a CETR tester under different pressures and different frequencies. The relationship between the tensile strength and the wear performance are studied. The morphologies of the worn surfaces under the typical test conditions are analyzed by means of scanning electron microscopy （SEM）. The analysis results show that at 10 MPa, satin 8/5 performs the best in friction-reduction and antiwear performance, and plain is the worst. At 30 MPa, however, the antiwear performance is reversed and satin 8/5 does not even complete the 2 h wear test at 16 Hz. There is no clear evidence proving that the tensile strength has an influence on the wear performance. So the different tribological performance of the three weave structures of fabric composites may be attributed to the different PTFE proportions in the fabric surface and the different wear mechanisms. The fabric composites are divided into three regions： the lubrication region, the reinforced region and the bonding region. The major mechanisms are fatigue wear and the shear effects of the friction force in the lubrication region. In the reinforced region fiber-matrix de-bonding and fiber breakage are involved. The proposed research proposes a regional wear model and further indicates the wear process and the wear mechanism of fabric composites.
文摘The Kevlar/polytetrafluroethylene（Kevlar/PTFE） fabric composite can be used as a self-lubricating liner of the self-lubricating bearing.Many types of nano-particles can improve the tribological performance of the polymer-based composite.Unfortunately,up to now,published work on the effect of nano-particles on the tribological performance of the fabric composite which can be used as a self-lubricating liner is quite scarce.Therefore,for the purpose of exploring a way to significantly improve the tribological performance of the fabric composite,the tribological performance of the Kevlar/PTFE fabric composite filled with nano-titania is evaluated by using the block-on-ring wear tester.The scanning electron microscopy is utilized to observe the morphologies of worn surfaces of the fabric composites and the counterparts.The tensile properties of the composites are evaluated on the universal material testing machine.The test results show that the addition of nano-titania at a proper mass fraction of the matrix resin improves the wear resistance and the tensile strength,decreases the friction coefficient,and makes the wear volume of the composite reach a relative steady state more quickly;plastic deformation and microcutting are important for the wear of the fabric composite;a lubricating layer is formed on the worn surface of the composite during sliding,and the lubricating layer is critical for the tribological performance of the composite;the formation and properties of the lubricating layer are influenced by the nano-titania particles.The proposed study on the effect of nano-titania on the tribological performance of the Kevlar/PTFE fabric composite,especially on the evolution of the worn surface of the composite,provides the basis for further understanding of the influence mechanism of the nano-particles on the tribological performance of the composite and explores a method of improving the tribological performance of the composite.
文摘In this work, the polytetrafluoroethylene (PTFE)-based composite substrates were manufactured by mixing, calendering, hot-pressing sintering. The composition of all the samples was PTFE, SiO2 and chopped E-glass fibers. The effects of content of E-glass fibers on the properties of the SiO2 filled PTFE composites were investigated, including density, water absorption, dielectric properties (εr, tanδ), coefficient of thermal expansion (CTE) and temperature coefficient of dielectric constant (τε). The compositions of inorganic materials mixture are (62 ? x) % SiO2 + x % E-glass fiber (x: mass ratio to composites, x = 0, 1, 1.5, 2, 2.5, 3). The results show that as the content of E-glass fibers is 2.5 wt.%, this composite obtains optimal properties, including excellent dielectric properties (εr^2.9123, tanδ~0.0011), acceptable water absorption of 0.075%, temperature coefficient of dielectric constant of 10 ppm/?C and coefficient of thermal expansion of 15.87 ppm/?C.
