arXiv subjects

B. N. J. Persson

Publications and source records attributed to B. N. J. Persson.

At least 37 records · Page 2Linked to original sources

arXiv2025

Rubber Wear: History, Mechanisms, and Perspectives

This paper presents a comprehensive review of wear mechanisms, with a primary focus on rubber wear under sliding conditions. Beginning with classical wear theories, including the Archard and Rabinowicz models, we analyze their applicability to both metals and elastomers and discuss extensions relevant to elastic contact and multiscale surface roughness. Various experimental studies on rubber, such as abrasion by sharp tools, erosion by particle impact, and wear during sliding on rough substrates, are reviewed and interpreted. The effects of environmental factors, such as oxygen and lubrication, are also discussed. In addition, we review a recently proposed wear model based on fatigue crack growth within asperity contact regions, which accounts for energy dissipation and multiscale interactions. This model explains the wide variability in the wear coefficient and predicts wear rates consistent with experimental observations across a broad range of conditions. It also explains the formation mechanism and provides the size distribution of rubber wear particles, from micrometer-scale up to severe cut-chip-chunk (CCC) wear. The results have implications for tire wear and the environmental impact of microscale wear debris (microplastics).

cond-mat.soft↗

arXiv2024

Rubber wear: experiment and theory

We study the wear rate (mass loss per unit sliding distance) of a tire tread rubber compound sliding on concrete paver surfaces under dry and wet conditions, at different nominal contact pressures of $σ_0 = 0.12$, $0.29$, and $0.43 \ {\rm MPa}$, and sliding velocities ranging from $v= 1 \ {\rm μm/s}$ to $1 \ {\rm cm/s}$. We find that the wear rate is proportional to the normal force and remains independent of the sliding speed. Sliding in water and soapy water results in significantly lower wear rates compared to dry conditions. The experimental data are analyzed using a theory that predicts wear rates and wear particle size distributions consistent with the experimental observations.

cond-mat.soft↗

arXiv2024

Influence of temperature and crack-tip speed on crack propagation in elastic solids

I study the influence of temperature and the crack-tip velocity of the bond breaking at the crack tip in rubber-like materials. The bond breaking is considered as a stress-aided thermally activated process and result in an effective crack propagation energy which increases strongly with decreasing temperature or increasing crack-tip speed. This effect is particular important for adhesive (interfacial) crack propagation but less important for cohesive crack propagation owing to the much larger bond-breaking energies in the latter case. For adhesive cracks the theory results are consistent with adhesion measurements for silicone (PDMS) rubber in contact with silica glass surfaces. For cohesive cracks the theory agree well with experimental results PDMS films chemically bound to silinized glass.

cond-mat.mtrl-sci↗

arXiv2024

On how to determine surface roughness power spectra

Analytical contact mechanics theories depend on surface roughness through the surface roughness power spectrum. In the present study, we evaluated the usability of various experimental methods for studying surface roughness. Our findings indicated that height data obtained from optical methods often lack accuracy and should not be utilized for calculating surface roughness power spectra. Conversely, engineering stylus instruments and atomic force microscopy (AFM) typically yield reliable results that are consistent across the overlapping roughness length scale region. For surfaces with isotropic roughness, the two-dimensional (2D) power spectrum can be derived from the one-dimensional (1D) power spectrum using several approaches, which we explored in this paper.

cond-mat.mtrl-sci↗

arXiv2024

Brownian friction dynamics: fluctuations in sliding distance

We have studied the fluctuation (noise) in the position of sliding blocks under constant driving forces on different substrate surfaces. The experimental data are complemented by simulations using a simple spring-block model where the asperity contact regions are modeled by miniblocks connected to the big block by viscoelastic springs. The miniblocks experience forces that fluctuate randomly with the lateral position, simulating the interaction between asperities on the block and the substrate. The theoretical model provides displacement power spectra that agree well with the experimental results.

cond-mat.soft↗

arXiv2024

Some comments on the fracture of viscoelastic solids

Crack propagation in viscoelastic solids like rubber is of great practical importance. Shrimali and Lopez-Pamies have proposed a new interesting approach for the crack propagation in viscoelastic solids. We give comments on the validity of the theory and point out some effects not included in the theory.

cond-mat.soft↗

arXiv2023

Surface roughness induced stress concentration

When a body is exposed to external forces large local stresses may occur at the surface because of surface roughness. Surface stress concentration is important for many applications and in particular for fatigue due to pulsating external forces. For randomly rough surfaces I calculate the probability distribution of surface stress in response to a uniform external tensile stress with the displacement vector field parallel to the rough surface. I present numerical simulation results for the stress distribution $σ(x,y)$ and show that in a typical case, the maximum local tensile stress may be $\sim 10$ times bigger than the applied stress. I discuss the role of the stress concentration on plastic deformation and surface crack generation and propagation.

cond-mat.soft↗

arXiv2022

Heat transfer in granular media with weakly interacting particles

We study the heat transfer in weakly interacting particle systems in vacuum. The particles have surface roughness with self-affine fractal properties, as expected for mineral particles produced by fracture, e.g., by crunching brittle materials in a mortar. We show that the propagating electromagnetic (EM) waves and the evanescent EM-waves, which occur outside of all solids, give the dominant heat transfer for large and small particles, respectively, while the phononic contribution from the area of real contact is negligible. As an application we discuss the heat transfer in rubble pile asteroids.

physics.app-ph↗

arXiv2021

On the stability of spinning asteroids

Most asteroids with a diameter larger than $\sim 300 \ {\rm m}$ are rubble piles i.e. consisting of more than one solid object. All asteroids are rotating but almost all asteroids larger than $\sim 300 \ {\rm m}$ rotate with a period longer than $2.3 \ {\rm hours}$, which is the critical period where the centrifugal force equals the gravitational force. This indicates that there are nearly no adhesive interaction forces between the asteroid fragments. We show that this is due to the surface roughness of the asteroid particles which reduces the van der Waals interaction between the particles by a factor of $100$ for micrometer sized particles and even more for larger particles. We show that surface roughness results in an interaction force which is independent of the size of the particles, in contrast to the linear size dependency expected for particles with smooth surfaces. Thus, two stone fragments of size $100 \ {\rm nm}$ attract each other with the same non-gravitational force as two fragments of size $10 \ {\rm m}$.

astro-ph.EP↗

arXiv2021

Air, helium and water leakage in rubber O-ring seals with application to syringes

We study the leakage of fluids (liquids or gases) in syringes with glass barrel, steel plunger and rubber O-ring stopper. The leakrate depends on the interfacial surface roughness and on the viscoelastic properties of the rubber. Random surface roughness is produced by sandblasting the rubber O-rings. We present a very simple theory for gas flow which takes into account both the diffusive and ballistic flow. The theory shows that the interfacial fluid flow (leakage) channels are so narrow that the gas flow is mainly ballistic (the so called Knudsen limit). We compare the leakrate obtained using air and helium. For barrels filled with water we observe no leakage even if leakage occurs for gases. We interpret this as resulting from capillary (Laplace pressure or surface energy) effects.

cond-mat.soft↗

arXiv2021

Air leakage in seals with application to syringes

We study the leakage of air in syringes with Teflon coated rubber stopper and glass barrel. The leakrate depends on the interfacial surface roughness, the viscoelastic properties of the rubber and on the elastoplastic properties of the Teflon coating. The measured leakage rates are compared to the predictions of a simple theory for gas flow, which takes into account both the diffusive and ballistic air flow, and the elastoplastic multiscale contact mechanics which determines the probability distribution of interfacial separations. The theory shows that the interfacial air flow (leakage) channels are so narrow that the gas flow is mainly ballistic (the so called Knudsen limit). The implications for container closure integrity is discussed.

cond-mat.soft↗

arXiv2021

On opening crack propagation in viscoelastic solids

We show that the Persson-Brener theory of crack propagation in viscoelastic solids gives a viscoelastic fracture energy factor $G/G_0 = 1+f$ which is nearly the same as the viscoelastic factor obtained using the cohesive-zone model. We also discuss finite-size effects and comment on the use of crack propagation theories for "solids" with a viscoelastic modulus that vanishes at zero frequency.

cond-mat.soft↗

arXiv2021

Side-leakage of facemask

Face masks are used to trap particles (or fluid drops) in a porous material (filter) in order to avoid or reduce the transfer of particles between the human lungs (or mouth and nose) and the external environment. The air exchange between the lungs and the environment is assumed to occur through the facemask filter. However, if the resistance to air flow through the filter is high some air (and accompanied particles) will leak through the filter-skin interface. In this paper I will present a model study of the side-leakage problem.

cond-mat.soft↗

arXiv2020

Physics of suction cups in air and in water

We present experimental results for the dependency of the pull-off time (failure time) on the pull-off force for suction cups in the air and in water. The results are analyzed using a theory we have developed for the contact between suction cups and randomly rough surfaces. The theory predicts the dependency of the pull-off time (failure time) on the pull-off force, and is tested with measurements performed on suction cups made from a soft polyvinyl chloride (PVC). As substrates we used sandblasted poly(methyl methacrylate) (PMMA). The theory is in good agreement with the experiments in air, except for surfaces with the root-mean-square (rms) roughness below $\approx 1 \ {\rm μm}$, where we observed lifetimes much longer than predicted by the theory. We show that this is due to out-diffusion of plasticizer from the soft PVC, which block the critical constrictions along the air flow channels. In water some deviation between theory and experiments is observed which may be due to capillary forces. We discuss the role of cavitation for the failure time of suction cups in water.

cond-mat.soft↗

arXiv2020

Rubber adhesion and friction: role of surface energy and contamination films

We study the influence of the surface energy and contamination films on rubber adhesion and sliding friction. We find that there is a transfer of molecules from the rubber to the substrate which reduces the work of adhesion and makes the rubber friction insensitive to the substrate surface energy. We show that there is no simple relation between adhesion and friction: adhesion is due to (vertical) detachment processes at the edge of the contact regions (opening crack propagation), while friction in many cases is determined mainly by (tangential) stick-slip instabilities of nanosized regions, within the whole sliding contact. Thus while the pull-off force in fluids may be strongly reduced (due to a reduction of the work of adhesion), the sliding friction may be only slightly affected as the area of real contact may be dry, and the frictional shear stress in the contact area nearly unaffected by the fluid.

cond-mat.soft↗

arXiv2020

A simple model for viscoelastic crack propagation

When a crack propagate in a viscoelastic solid energy dissipation can occur very far from the crack tip where the stress field may be very different from the $r^{-1/2}$ singular form expected close to the crack tip. Most theories of crack propagation focus on the near crack-tip region. Remarkable, here I show that a simple theory which does not account for the nature of the stress field in the near crack-tip region result in a crack propagation energy in semi-quantitative agreement with a theory based on the stress field in the near crack-tip region. I consider both opening and closing crack propagation, and show that for closing crack propagation in viscoelastic solids, some energy dissipation processes must occur in thecrack tip process zone.

cond-mat.soft↗

arXiv2020

Viscoelastic crack propagation: review of theories and applications

We review a theory of crack propagation in viscoelastic solids. We consider both cracks in infinite systems and in finite sized systems. As applications of the theory we consider two adhesion problems, namely pressure sensitive adhesives and the ball-flat adhesion problem. We also study crack propagation in the pig skin dermis, which is of medical relevance, and rubber wear in the context of tires.

cond-mat.soft↗

arXiv2020

Fluid leakage in metallic seals

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 $\approx 8$

cond-mat.soft↗