tribology

Ernest Rabinowicz’s words, spoken two decades ago in his groundbreaking textbook on the friction and wear of materials [1], continue to resonate today: ’Although wear is an important topic, it has never received the attention it deserves.’ Rabinowicz’s work laid the foundation for contemporary tribology research [2]. Wear, characterized as the removal and deformation of material on a surface due to the mechanical action of another surface, carries significant consequences for the economy, sustainability, and poses health hazards through the emission of small particles. According to some estimates [1, 3], the economic impact is substantial, accounting for approximately 5% of the Gross National Product (GNP).

Despite its paramount importance, scientists and engineers often shy away from wear analysis due to the intricate nature of the underlying processes. Wear is often perceived as a ”dirty” topic, and with good reason. It manifests in various forms, each with its own intricacies, arising from complex chemical and physical processes. These processes unfold at different stages, creating a time-dependent phenomenon influenced by key parameters such as sliding velocity, ambient or local temperature, mechanical loads, and chemical reactions in the presence of foreign atoms or humidity.

The review paper by Vakis et al. [5] provides a broad perspective on the complexity of tribology problems. This complexity has led to numerous isolated studies focusing on specific wear mechanisms or processes. The proliferation of empirical wear models in engineering has resulted in an abundance of model variables and fit coefficients [6], attempting to capture the intricacies of experimental data.

Tribology faces a fundamental challenge due to the multitude of interconnected scales. Surfaces exhibit roughness with asperities occurring at various wavelengths. Only a small fraction of these asperities come into contact, and an even smaller fraction produces wear debris. The reasons behind why, how, and when this occurs are not fully understood. The debris gradually alter the surface profile and interacts with one another, either being evacuated from the contact interface or gripping it, leading to severe wear. Due to this challenge of scales, contributions of numerical studies in wear research over the past decades sum up to less than 1% (see Fig. 1). Yet, exciting opportunities exist for modeling, which we attempt to discuss here.

While analyzing a single asperity contact may not unveil the entire story, it arguably represents the most fundamental level to comprehend wear processes. This blog entry seeks to encapsulate the authors’ perspective on this rapidly evolving topic. Acknowledging its inherent bias, the aim is to spark controversies and discussions that contribute to a vibrant blogosphere on the mechanics of the process.

The subsequent section delves into the authors’ endeavors in modeling adhesive wear at the asperity level. Section 3 navigates the transition to abrasive wear, while Section 4 explores opportunities for upscaling asperity-level mechanisms to the meso-scale, with the aspiration of constructing predictive models. Lastly, although the primary focus of this blog entry is on modeling efforts, it would be remiss not to mention a few recent advances on the experimental front.

Specifically, the post requires expert knowledge in experimental and/or computational mechanics of materials and/or tribology. The position is part of a large international EPSRC-SFI funded project aimed at developing next generation textile triboelectric nanogenerators (or T-TENGs) for powering of wearable electronics.  This position will focus on the mechanics and tribology of T-TENGs and will involve both modelling and experimental work.

Postdoc position available on Mechanics/Tribology and/or Triboelectric Nanogenerators at the University of Glasgow's James Watt School of Engineering. Applicants with background in mechanics, tribology or triboelectric nanogenerators (including device fabrication and testing) are welcome. Closing date: 08-Dec-2020

THE SCHOOL OF ENGINEERING AND APPLIED SCIENCE at the UNIVERSITY OF PENNSYLVANIA invites applications for a full-time position as a Postdoctoral Researcher in the DEPARTMENT OF MECHANICAL ENGINEERING AND APPLIED MECHANICS in the laboratory of Prof. Robert W. Carpick (http://carpick.seas.upenn.edu).

Static friction at fractal interfaces

https://doi.org/10.1016/j.triboint.2015.09.016

The new book "Modeling and Simulation of Tribological Problems in Technology" (CISM book series, Springer) has been published: https://link.springer.com/book/10.1007/978-3-030-20377-1

Editors: Paggi, Marco (IMT School for Advanced Studies Lucca, Italy), Hills, David (University of Oxford)

Advanced Course at the International Centre for Mechanical Sciences (CISM, Udine, Italy)

Modelling and Simulation of Tribological Problems in Technology

May 28, 2018 — June 1, 2018 

Coordinators:

Marco Paggi (IMT School for Advanced Studies Lucca, Lucca, Italy)

David A. Hills (University of Oxford, Oxford, Great Britain)