Rough viscoelastic sliding contact: Theory and experiments (original) (raw)
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New insights into viscoelastic contact mechanics between rough solids
The optimized design of a large variety of rubber-made engineering applications (e.g. tires, dampers, rubber seals) needs the full solution of many mechanical problems involving viscoelasticity. Particularly interesting is the sliding contact mechanics of rough viscoelastic solids, where, in addition to the convoluted nature of the material response, the surface roughness boosts the problem complexity. In this paper, by employing the adaptive non uniform mesh developed by the authors in [1,2] and the mathematical formulation proposed in [3], we focus on the main aspects of this issue, i.e. the viscoelastic dissipative phenomena and the viscoelastic induced anisotropy.
Numerical simulations of rough contacts between viscoelastic materials
IOP Conference Series: Materials Science and Engineering, 2017
The durability of the mechanical contact is often plagued by surface-related phenomena like rolling contact fatigue, wear or crack propagation, which are linked to the important gradients of stress arising in the contacting bodies due to interaction at the asperity level. The semi-analytical computational approach adopted in this paper is based on a previously reported algorithm capable of simulating the contact between bodies with arbitrary limiting surfaces and viscoelastic behaviour, which is enhanced and adapted for the contact of real surfaces with microtopography. As steep slopes at the asperity level inevitably lead to localized plastic deformation at the tip of the asperities that are first brought into contact, the viscoelastic behaviour is amended by limiting the maximum value of the pressure on the contact area to that of the material hardness, according to the Tabor equation. In this manner, plasticity is considered in a simplified manner that assures the knowledge of the contact area and of the pressure distribution without estimation of the residual state. The main advantage of this approach is the preservation of the algorithmic complexity, allowing the simulation of very fine meshes capable of capturing particular features of the investigated contacting surface. The newly advanced model is expected to predict the contact specifics of rough surfaces as resulting from various manufacturing processes, thus assisting the design of durable machine elements using elastomers or rubbers. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Modelling of Rough Contact between Linear Viscoelastic Materials
Modelling and Simulation in Engineering
The important gradients of stress arising in rough mechanical contacts due to interaction at the asperity level are responsible for damage mechanisms like rolling contact fatigue, wear, or crack propagation. The deterministic approach to this process requires computationally effective numerical solutions, capable of handling very fine meshes that capture the particular features of the investigated contacting surface. The spatial discretization needs to be supported by temporal sampling of the simulation window when time-dependent viscoelastic constitutive laws are considered in the description of the material response. Moreover, when real surface microtopography is considered, steep slopes inevitably lead to localized plastic deformation at the tip of the asperities that are first brought into contact. A computer model for the rough contact of linear viscoelastic materials, capable of handling deterministic contact geometry, complex viscoelastic models, and arbitrary loading histori...
Incipient sliding of rough surfaces in contact- a multiscale numerical analysis.pdf
In this paper, the Cattaneo theory of frictional contact is extended to elastic half-spaces in contact through rough disordered interfaces. The discrete version of the Cattaneo theorem is provided, and represents the basis of a multiscale numerical contact algorithm. Mathematical surfaces with imposed roughness, as well as experimentally digitised ones, are analysed. By means of a numerical method, the evolution of the contact domain, at dierent resolution, is investigated. Roughness of the interfaces provides lacunarity of the contact domains, whose fractal dimension is always smaller than 2.0. When a tangential force is applied, the extent of the stick area decreases in the same way as the contact area develops with increasing pressure, and the slip area is found to be proportional to the tangential force, as predicted by Cattaneo theory. The evolution of the shear centroid, as well as the amount of dissipated energy up to full-sliding, are provided. Finally, it is shown that, at a sucient level of discretization, the distribution of contact pressures is multifractal. Ó
Micromechanical analysis of friction anisotropy in rough elastic contacts
International Journal of Solids and Structures, 2014
Computational contact homogenization approach is applied to study friction anisotropy resulting from asperity interaction in elastic contacts. Contact of rough surfaces with anisotropic roughness is considered with asperity contact at the micro scale being governed by the isotropic Coulomb friction model. Application of a micro-to-macro scale transition scheme yields a macroscopic friction model with orientation-and pressure-dependent macroscopic friction coefficient. The macroscopic slip rule is found to exhibit a weak non-associativity in the tangential plane, although the slip rule at the microscale is associated in the tangential plane. Counterintuitive effects are observed for compressible materials, in particular, for auxetic materials.
Lubricants, 2020
A computational approach that is based on interface finite elements with eMbedded Profiles for Joint Roughness (MPJR) is exploited in order to study the viscoelastic contact problems with any complex shape of the indenting profiles. The MPJR finite elements, previously developed for partial slip contact problems, are herein further generalized in order to deal with finite sliding displacements. The approach is applied to a case study concerning a periodic contact problem between a sinusoidal profile and a viscoelastic layer of finite thickness. In particular, the effect of using three different rheological models that are based on Prony series (with one, two, or three arms) to approximate the viscoelastic behaviour of a real polymer is investigated. The method allows for predicting the whole transient regime during the normal contact problem and the subsequent sliding scenario from full stick to full slip, and then up to gross sliding. The effects of the viscoelastic model approxima...
Modeling of nonlinear viscoelastic–viscoplastic frictional contact problems
International Journal of Engineering Science, 2014
This paper presents a nonlinear time-dependent computational model for analyzing the quasistatic response of viscoelastic-viscoplastic frictional contact problems. Both material and geometrical nonlinearities are considered in the framework of the Lagrangian description. The material nonlinearity is due to the time-stress-dependency of the constitutive equation, while the geometrical nonlinearity is due to large displacements and rotations, but small strains. The model is derived based on an implicit time-integration method within a general displacement-based finite element analysis. The nonlinear Schapery's single integral model is used to model the viscoelastic part, while the Perzyna model is adopted model the viscoplastic part. The exponential form of the Prony series is used to represent the transient component of the viscoelastic creep compliance, since it permits hereditary effects to be computed recursively. In addition, an incremental form of the viscoplastic strain component is derived in the framework of associative viscoplasticity based on implicit integration scheme. Throughout the contact interface, friction is simulated using a local-nonlinear friction law, while the Lagrange multiplier method is adopted to model the inequality contact constraints. In a presented case study, the complete contact configuration and internal stresses are analyzed. Results show the significant effects of material nonlinearity, viscoplastic flow, and friction on the response of contact problems.
A 3D contact investigation of rough surfaces considering elastoplasticity
2008
In this work a homogenization method presented by Bandeira et al is enhanced to obtain by numerical simulation interface laws for the normal contact pressure based on statistical surface models. For this purpose elastoplastic behaviour of the asperities is introduced. Statistical evaluations of numerical simulations lead to a constitutive law for the contact pressure. The resulting law compared with other laws stemming from analytical investigations, like Greenwood Williamson and Yovanovich . The non-penetration condition and interface models for contact taking into account the surface microstructure are investigated in detail. This paper can be regarded as a complementary study to that presented by Bandeira et al . Here the plasticity of the asperities is taken into account by assuming a constitutive equation based on associated von Mises criterium formulated in principal axes.
Mechanism and Machine Theory, 2015
The nature of the constitutive contact force law utilized to describe contact-impact events in solid contact interfaces plays a key role in predicting the response of multibody mechanical systems and in the simulation of engineering applications. The goal of this work is to present a comparative study on the most relevant existing viscoelastic contact force models. In the sequel of this process, their fundamental characteristics are examined and their performances evaluated. Models developed based on the Hertz contact theory and augmented with a damping term to accommodate the dissipation of energy during the impact process, which typically is a function of the coefficient of restitution between the contacting solids, are considered in this study. In particular, the identified contact force models are compared in the present study for simple solid impact problems with the sole purpose of comparing the performance of the various models and examining the corresponding system behavior. The outcomes indicate that the prediction of the dynamic behavior of contacting solids strongly depends on the selection of the contact force model.