Frictional properties of multi-asperity surfaces at the nanoscale

Santhapuram, Raghuram R.; Nair, Arun K.

doi:10.1016/j.commatsci.2017.05.001

Cited by 15 publications

(4 citation statements)

References 41 publications

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“…The general approach seems to assume that the peak heights of the asperities obey the Gaussian distribution and each contact of the asperities is the Hertzian contact. With the development of computational approaches, some studies in recent years have utilized the finite element method (FEM) for the contact analysis of the interfaces in microscale [11][12][13][14]. These studies have measured or preliminarily presumed the surface profile of the interfaces and created the finite element (FE) model of the micro asperities.…”

Section: Introductionmentioning

confidence: 99%

Interfacial Element for Finite Element Modal Analysis of Bolted Joints

Kishimoto¹,

Kobayashi²,

Ohtsuka³

et al. 2021

14th WCCM-ECCOMAS Congress

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Multi-material structures are going to be a main scheme to construct automobiles. For the construction of multi-material structures, techniques to join dissimilar materials are required. The major joining techniques are classified into welding, adhesion and mechanical fastening such as bolted joints and riveting. Especially, bolted joints enable joining of metallic materials (steel and aluminium alloy, etc.) and non-metallic materials (CFRP, etc.) with high joint strength. However, the total stiffness of structures with bolted joints is relatively low because interfaces in bolted joints just contact each other, and its interfacial stiffness is lower than elastic modulus of base materials. Moreover, interfacial stiffness of bolted joints depends on clamping force of bolt and nut. This study has proposed an interfacial element for finite element modal analysis of bolted joints. The interfacial element simulates interfacial stiffness of bolted joints. Contact of interfaces is assumed to be the Hertzian contact of elastic asperities whose peak heights obey the Gaussian distribution. Based on this assumption, the stiffness of the interfacial element is derived from the compressive stress and the surface texture of the interfaces. By using the finite element model with the interfacial element, the modal analysis computes the natural frequency and the vibration mode. Finite element simulations and hammering tests have been conducted with several bolted joints. In general, the natural frequency of the bolted joints in the hammering tests increases with the increase in the clamping force, but it is lower than the calculation results in which the stiffness reduction of the jointed interfaces is ignored. The calculation results by using the proposed interfacial element agree with the hammering tests. Therefore, the proposed interfacial element contributes to improvement of modal analysis of bolted joints by mathematically modelling stiffness reduction of jointed interfaces based on tribology.

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Section: Introductionmentioning

confidence: 99%

Interfacial Element for Finite Element Modal Analysis of Bolted Joints

Kishimoto¹,

Kobayashi²,

Ohtsuka³

et al. 2021

14th WCCM-ECCOMAS Congress

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show abstract

“…The surface with a lower texture density reduced the grinding forces and average COFs effectively, while the influence of texture orientation was slight, due to a high cutting depth. Santhapuram et al [18] performed MD simulations on the friction properties of an aluminum surface with cylindrical and spherical textures, and the COFs depended on texture shape and tip radius. Using a multiscale method, Tong et al [19,20] investigated the friction behaviors of the sliding contacts between rigid tips and textured surfaces, and a higher texture height and larger texture spacing could reduce the friction forces for the rectangular textures, but the model was a two dimensional one.…”

Section: Introductionmentioning

confidence: 99%

Influence of Nanoscale Textured Surfaces and Subsurface Defects on Friction Behaviors by Molecular Dynamics Simulation

Tong

Quan

Zhao³

et al. 2019

Nanomaterials

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In nanomaterials, the surface or the subsurface structures influence the friction behaviors greatly. In this work, nanoscale friction behaviors between a rigid cylinder tip and a single crystal copper substrate are studied by molecular dynamics simulation. Nanoscale textured surfaces are modeled on the surface of the substrate to represent the surface structures, and the spacings between textures are seen as defects on the surface. Nano-defects are prepared at the subsurface of the substrate. The effects of depth, orientation, width and shape of textured surfaces on the average friction forces are investigated, and the influence of subsurface defects in the substrate is also studied. Compared with the smooth surface, textured surfaces can improve friction behaviors effectively. The textured surfaces with a greater depth or smaller width lead to lower friction forces. The surface with 45° texture orientation produces the lowest average friction force among all the orientations. The influence of the shape is slight, and the v-shape shows a lower average friction force. Besides, the subsurface defects in the substrate make the sliding process unstable and the influence of subsurface defects on friction forces is sensitive to their positions.

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“…The general approach seems to be based on the assumption in which the peak heights of the asperities obey the Gaussian distribution and each contact of the asperities is the Hertzian contact. With the development of the computational approaches, some studies in recent years have utilized the finite element method (FEM) for the contact analysis of the interfaces in microscale (Karupannasamy et al, 2013;Hol et al, 2015;Wagner et al, 2015;Santhapuram and Nair, 2017). These studies have actually measured or preliminarily presumed the surface profile of the interfaces, and created the finite element (FE) model of the micro asperities.…”

Section: Introductionmentioning

confidence: 99%

Estimation method of interfacial stiffness of bolted joint in multi-material structure by inverse analysis

Kishimoto

Kobayashi

Ohtsuka

et al. 2019

Mechanical Engineering Journal

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Multi-material structure is expected to be the main scheme to construct automobiles. Many methods have been studied to properly fix or bond dissimilar materials. The fixing by the bolts and nuts is one of the primary fixing methods, and has the advantage of easy assembly and disassembly. The interfacial stiffness of the bolted joints is lower than the stiffness of the base materials and varied by the clamping force of the bolts and nuts, because the micro asperities formed on the interfaces just contact each other. The contact analysis by using the surface profile of the interfaces in microscale is one of the accurate estimations. However, the estimation method of the interfacial stiffness in macroscale is also necessary for the in-situ evaluation. This study has developed an estimation method of the interfacial stiffness by the inverse analysis of the clamping force and the natural frequency of the structure. The inverse analysis algorithm introduces the mathematical model of the interfaces in which the contact of the surfaces is assumed to be the contact of the elastic asperities whose peak heights obey the Gaussian distribution. The hammering test was conducted by using the specimen which consisted of the steel plate and the aluminum alloy plate joined by the bolts and nuts. Moreover, as the contact analysis, the finite element method simulated the contact of the asperities formed on the interfaces by using the surface profile of the interfaces. The results showed that the proposed method could estimate the interfacial stiffness which reproduced the natural frequency of the specimen subjected to the clamping force of the bolts and nuts. The interfacial stiffness estimated by the proposed method was comparable to that calculated by the contact analysis.

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Frictional properties of multi-asperity surfaces at the nanoscale

Cited by 15 publications

References 41 publications

Interfacial Element for Finite Element Modal Analysis of Bolted Joints

Interfacial Element for Finite Element Modal Analysis of Bolted Joints

Influence of Nanoscale Textured Surfaces and Subsurface Defects on Friction Behaviors by Molecular Dynamics Simulation

Estimation method of interfacial stiffness of bolted joint in multi-material structure by inverse analysis

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