Plastic contact of self-affine surfaces: Persson’s theory versus discrete dislocation plasticity

Venugopalan, Syam Parayil; Irani, Nilgoon; Nicola, Lucia

doi:10.1016/j.jmps.2019.07.019

Cited by 27 publications

(22 citation statements)

References 27 publications

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“…The polymers used in our study are semi-crystalline, and since the crystalline domains are of micrometer size and have different mechanical properties than the amorphous regions, inhomogeneous flow on the microscale occurs during plastic flow. How plastic flow generate surface roughness for metallic-like crystalline solids was shown recently in a very interesting study by Venugopalan et al [19]. In the calculations we have used the measured surface roughness power spectra of the sandblasted polymer balls, penetration hardness from the conical indenter (see Table 1) and the Young's elastic modulus from the literature [23] (E = 0.7, 2.1, 1.2, 1.25 and 2.0 GPa for PTFE, PC, nylon, UHMWPE and PP, respectively).…”

Section: Asperity Deformations and Contact Areamentioning

confidence: 83%

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Contact Mechanics for Solids with Randomly Rough Surfaces and Plasticity

Tiwari¹,

Wang

Müser

et al. 2019

Lubricants

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We present experimental results for the elastic and plastic deformation of sandblasted polymer balls resulting from contacts with flat smooth steel and silica glass surfaces. Nearly symmetric, Gaussian-like height probability distributions were observed experimentally before and remarkably, also after the polymer balls were deformed plastically. For all the polymers studied we find that the surface roughness power spectra for large wavenumbers (short length scales) are nearly unchanged after squeezing the polymer balls against flat surfaces. We attribute this to non-uniform plastic flow processes at the micrometer length scale. The experimental data are analyzed using the Persson contact mechanics theory with plasticity and with finite-element method (FEM) calculations.

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Section: Asperity Deformations and Contact Areamentioning

confidence: 83%

“…[5]), and was in fact used in the study presented in Ref. [19]. It is less clear how to include strain hardening in this approach.…”

Section: Asperity Deformations and Contact Areamentioning

confidence: 99%

Contact Mechanics for Solids with Randomly Rough Surfaces and Plasticity

Tiwari¹,

Wang

Müser

et al. 2019

Lubricants

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“…Deshpande and co-workers [ 21 , 33 ] performed monotonic micro-sliding discrete dislocation plasticity (DDP) simulations to investigate the dislocation structure and surface behaviour under sliding. Nicola and co-workers [ 34 , 35 , 36 ] have also employed the DDP framework to understand the activity of dislocations under multi-asperity, self-affine contact, and the roughness (i.e., the height of the asperities) has been shown to play a key role in the development of plasticity in the subsurface. To the authors’ knowledge, there is no computational framework published for fretting fatigue using DDP.…”

Section: Introductionmentioning

confidence: 99%

On the Origin of Plastic Deformation and Surface Evolution in Nano-Fretting: A Discrete Dislocation Plasticity Analysis

Balint

Dini

2021

Materials

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Discrete dislocation plasticity (DDP) calculations were carried out to investigate a single-crystal response when subjected to nano-fretting loading conditions in its interaction with a rigid sinusoidal asperity. The effects of the contact size and preceding indentation on the surface stress and profile evolution due to nano-fretting were extensively investigated, with the aim to unravel the deformation mechanisms governing the response of materials subjected to nano-motion. The mechanistic drivers for the material’s permanent deformations and surface modifications were shown to be the dislocations’ collective motion and piling up underneath the contact. The analysis of surface and subsurface stresses and the profile evolution during sliding provides useful insight into damage and failure mechanisms of crystalline materials subject to nano-fretting; this can lead to improved strategies for the optimisation of material properties for better surface resistance under micro- and nano-scale contacts.

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“…[27,28]. Several studies of surface roughness and plastic flow have been reported using microscopic (atomistic) models [29], or models inspired by atomic scale phenomena that control the nucleation and glide of the dislocations [30][31][32][33]. These models supply fundamental insight into the complex process of plastic flow, but are not easy to apply to practical systems involving inhomogeneous polycrystalline metals and alloys exhibiting surface roughness of many length scales.…”

Section: Introductionmentioning

confidence: 99%

Fluid Leakage in Metallic Seals

Fischer¹,

Schmitz²,

Tiwari³

et al. 2020

Tribol Lett

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Metallic seals are crucial machine elements in many important applications, e.g., in ultrahigh vacuum systems. Due to the high elastic modulus of metals, and the surface roughness which exists on all solid surfaces, if no plastic deformation would occur one expects in most cases large fluid flow channels between the contacting metallic bodies, and large fluid leakage. However, in most applications plastic deformation occurs, at least at the asperity level, which allows the surfaces to approach each other to such an extent that fluid leakage often can be neglected. In this study, we present an experimental set-up for studying the fluid leakage in metallic seals. We study the water leakage between a steel sphere and a steel body (seat) with a conical surface. The experimental results are found to be in good quantitative agreement with a (fitting-parameter-free) theoretical model. The theory predicts that the plastic deformations reduce the leak-rate by a factor $$\approx 8$$ ≈ 8 .

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Plastic contact of self-affine surfaces: Persson’s theory versus discrete dislocation plasticity

Cited by 27 publications

References 27 publications

Contact Mechanics for Solids with Randomly Rough Surfaces and Plasticity

Contact Mechanics for Solids with Randomly Rough Surfaces and Plasticity

On the Origin of Plastic Deformation and Surface Evolution in Nano-Fretting: A Discrete Dislocation Plasticity Analysis

Fluid Leakage in Metallic Seals

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