An overview of the advances in studies on tribology of molecular deposition （MD） films is presented here to summarize the studies of nanofrictional properties, adhesion, wear and mechanical behavior, as well as the ...An overview of the advances in studies on tribology of molecular deposition （MD） films is presented here to summarize the studies of nanofrictional properties, adhesion, wear and mechanical behavior, as well as the molecular dynamics simulation of nanotribological properties of the film in the last decade. Some key research topics which need to be investigate further are addressed.展开更多
The triboelectric nanogenerator(TENG)is a new mechanical energy harvesting technology in which the typical viscoelastic material polydimethylsiloxane(PDMS)is widely used.Micro-/nano-textures are often fabricated on th...The triboelectric nanogenerator(TENG)is a new mechanical energy harvesting technology in which the typical viscoelastic material polydimethylsiloxane(PDMS)is widely used.Micro-/nano-textures are often fabricated on the PDMS surface to enhance the electrical performance of TENG.As the contact region decreases to micro/nano scale,the adhesive forces become dominant.However,there is still a lack of contact mechanics model considering both material viscoelasticity and the adhesive forces to guide the surface texture design.In this paper,the explicit data-fitting formulas based on the fractional derivative Zener model are firstly derived to identify the viscoelastic constitutive parameters,which can not only avoid the influence of the initial contact point,but also ensure the accurate conversion between the creep compliance and the relaxation modulus function.Then a viscoelastic-adhesive contact model based on the fitted constitutive parameters is established,and the numerical algorithms such as bi-conjugate stabilized(Bi-CGSTAB)method and fast Fourier transform(FFT)technique are employed to analyze the effects of material viscoelasticity and texture sizes on the contact and electrical performance.It is shown that,compared with results from the elastic-adhesive contact model,the contact area ratio based on the viscoelastic-adhesive contact model is significantly larger,which is much closer to the experimental results.Among the selected sizes of pyramid texture,the higher electrical performance can be obtained from the textures with a smaller pitch and a larger width under the heavier applied load.This study can provide a theoretical reference for the design of viscoelastic surface texture of TENG.展开更多
基金the National Natural Science Foundation of China(Grant No.50575171)the National Basic Research Program of China(Grant No.2007CB607604)the Open Financial Fund of the State Key Laboratory of Tribology of Tsinghua University(Grant No.SKLT05-02).
文摘An overview of the advances in studies on tribology of molecular deposition （MD） films is presented here to summarize the studies of nanofrictional properties, adhesion, wear and mechanical behavior, as well as the molecular dynamics simulation of nanotribological properties of the film in the last decade. Some key research topics which need to be investigate further are addressed.
基金This work is financially supported by National Natural Science Foundation of China(Nos.51735001 and 11472046).
文摘The triboelectric nanogenerator(TENG)is a new mechanical energy harvesting technology in which the typical viscoelastic material polydimethylsiloxane(PDMS)is widely used.Micro-/nano-textures are often fabricated on the PDMS surface to enhance the electrical performance of TENG.As the contact region decreases to micro/nano scale,the adhesive forces become dominant.However,there is still a lack of contact mechanics model considering both material viscoelasticity and the adhesive forces to guide the surface texture design.In this paper,the explicit data-fitting formulas based on the fractional derivative Zener model are firstly derived to identify the viscoelastic constitutive parameters,which can not only avoid the influence of the initial contact point,but also ensure the accurate conversion between the creep compliance and the relaxation modulus function.Then a viscoelastic-adhesive contact model based on the fitted constitutive parameters is established,and the numerical algorithms such as bi-conjugate stabilized(Bi-CGSTAB)method and fast Fourier transform(FFT)technique are employed to analyze the effects of material viscoelasticity and texture sizes on the contact and electrical performance.It is shown that,compared with results from the elastic-adhesive contact model,the contact area ratio based on the viscoelastic-adhesive contact model is significantly larger,which is much closer to the experimental results.Among the selected sizes of pyramid texture,the higher electrical performance can be obtained from the textures with a smaller pitch and a larger width under the heavier applied load.This study can provide a theoretical reference for the design of viscoelastic surface texture of TENG.
