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jfmolinari's picture

Journal club for December 2023 : Recent trends in modeling of asperity-level wear

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.

Postdoc/PhD positions on granular materials and computational mechanics, Tsinghua University

Multiple postdoc and one PhD positions are open at Tsinghua University. The research will take place at Tsinghua University’s Shenzhen International Graduate School (SIGS), located in Shenzhen, China, and is partly sponsored by NSFC and Tsinghua SIGS’s scientific research startup funds.

Postdoc/PhD positions on multiscale modeling of debris flow and sediment transport at Tsinghua University, Shenzhen, China

Multiple postdoc and PhD positions are open at Tsinghua University to investigate debris flow and sediment transport in fluvial and coastal environments through a multiscale approach integrating experiments, simulations, and theory. The research will take place at Tsinghua University’s Shenzhen International Graduate School (SIGS), located in Shenzhen, China, and is partly sponsored by NSFC and Tsinghua SIGS’s scientific research startup funds.

Arttu Polojärvi's picture

PhD position in multi-scale modeling of sea ice deformation

We are looking for a doctoral student to work multi-scale modeling of sea ice deformation on numerical modeling of ridging of sea ice by using discrete element method. Large-scale continuum models are typically used to study ice behavior with a resolution of some tens of kilometers. These models do not accurately describe small-scale processes related to deformation and failure of ice. In such models, the ice properties, such as compressive strength are tuned so that the models to present observed ice behavior. Predictive power of the models suffers from this.

gbuscarnera's picture

Postdoctoral positions in Granular Mechanics at Northwestern University

Applications are invited for two postdoctoral positions in the Geomechanics Group led by Dr. Buscarnera at Northwestern University. Both positions focus on the multi-scale behavior of granular solids, with one emphasizing numerical and theoretical modeling of the particle-continuum duality and the other emphasizing the experimental study of particulate materials through advanced characterization protocols.

Arttu Polojärvi's picture

Two PhD positions in Aalto University

Ice Mechanics Group at the Department of Mechanical Engineering of Aalto University is looking for two motivated doctoral students to work on numerical modeling and experiments on sea ice interacting with offshore wind farm. Novel numerical models for sea ice behavior and failure form a central part of the research by our group. Also we have a world unique experimental facility, Aalto Ice and Wave Tank.

Arttu Polojärvi's picture

PhD position in numerical ice mechanics, Aalto University, Finland

We are looking for a doctoral student to work on numerical modeling of ridging of sea ice. Ridging is central to understanding the behavior of sea ice from scales varying from tens of meters up to hundreds of kilometers and has a close connection to sea ice dynamics models, which have an important role in predicting the effects of climate change. The applicant should be advanced in solid and computational mechanics and have at least average programming skills.

Postdoctoral Position at Oregon State University: Rock-Tool Interaction

I have an opening for a new postdoctoral scholar to join my research group, please see attached. The project is on the field-scale calibration of DEM models. Primary responsibilities include developing and executing large-scale experiments, interpretation and synthesis of results, and collaboration with modelers to perform the calibrations.

Postdoc Position in Geomechanics at Oregon State University

I have an opening for a new postdoc to join my research group. The project is on the field-scale calibration of DEM models. Primary responsibilities include developing and executing large-scale experiments, interpretation and synthesis of results, and collaboration with modelers to perform the calibrations.

Postdoctoral Position in Discrete/Continuum Simulations

I am seeking to hire a postdoc in the area of coupled discrete-continuum modeling. The position is expected to start on 11/01/2019. Applicants who have experience with Itasca software (specifically, FLAC and PFC) are strongly encouraged to apply.

Please pass this announcement along to anyone whom you think might be interested. I would be happy to answer questions from any potential applicants.

Postdoctoral Position in Discrete Element Method Simulations

 

I am currently looking to hire a postdoc to work on DEM modeling of dynamic problems and impact events. The ideal candidate will have strong programming skills (C++/Python) and existing experience with open source software and GUI development. Full details may be found at this link. The announcement lists a start date of September 1, but this is flexible.

 

Payam Khazaeinejad's picture

PhD studentship available at Kingston University London

A PhD studentship is available in the Department of Mechanical Engineering at Kingston University London.

The work will be dedicated to the discrete element modeling of pellets' compaction in orodispersible tablets.

The project is in close collaboration with the Kingston University's Department of Pharmacy and also the University of Strathclyde. The student will have access to the high-performance computing facilities and also to the relevant facilities to obtain experimental data for validation of the developed numerical models.

QiushiChen's picture

Postdoc position in granular mechanics and discrete element modeling

A postdoc position is available in the area of computational mechanics, in particular, granular mechanics and discrete element modeling (DEM), in support of a Department of Energy-funded research project on Integrated Process Optimization for Biochemical Conversion. This is a multidisciplinary research project with collaborations between multiple academic institutions and the DOE's Idaho National Laboratory.

Compiling C++14 code on a cluster with clang

For those of you who have to port codes to supercomputers:

New article: Compling C++14 code on a cluster.  http://www.parresianz.com/dem/compiling-paraellip3d-for-a-cluster/

-- Biswajit

mac's picture

DEM Open Forum and ESyS-Particle Workshop

DEM Open Forum and ESyS-Particle Workshop

University of Glasgow

Wed., 30/08/2017, 8:30 am – Fri., 01/09/2017, 5:00 pm 

Arttu Polojärvi's picture

Doctoral Candidate Position in Computational Ice Mechanics

We are looking for a doctoral student to join our Arctic Marine and Ice Technology research group at the Aalto University (Finland), Department of Mechanical Engineering, to study ice-structure interaction process in shallow water using numerical simulations.  In the complex ice-structure interaction process an intact ice sheet fails into discrete ice blocks, which affect further stages of the process. Realistic calculations of ice loads due to this process require modeling of the ice blocks and their pile-up process.

dphull's picture

Underwater Soil Mechanics Problem

I am an undergraduate student conducting a research project involving the design of a tool to aid astronauts to perform experiments on lunar surfaces and would like to request some direction about which analytical tools would be best suited for this application (i.e. FEA or DEM software/techniques). The specific scenario of interest is to design a tool that can act as an anchor in a sand-like medium (regolith) on the surface of the moon.

Shailendra's picture

Post-doctoral positions at National University of Singapore (NUS) and Singapore University of Technology and Design (SUTD)

Starting April 2016, we will have openings for two post-doctoral fellow positions in experimental and computational mechanics of advanced polymers. These positions will support a new research program between Singapore University of Technology and Design (SUTD) and National University of Singapore (NUS) funded by Agency for Science, Technology and Research (A*STAR). The project focuses on synthesizing, characterizing, modeling, and simulating the thermo-mechanical behavior of polymers with covalent adaptable networks (CANs), e.g. vitrimers.

davm5's picture

Impact Force plotting using Abaqus/Explicit

Hello Everyone

I am trying to simulate material dumping process from shovel onto mining dump truck. And for that i am using Abaqus/Explicit.  When i plot the contact force of material falling onto truck body under gravity, it gives me the maximum value of 0.12e+11, where as a simple theoretical analysis shows that the resulting impact force for 100 tons of material falling under gravity should be 9e5 N. I am not been able to understand the reason that why Abaqus /Explicit is exaggerating the impact/contact force so much. And i dont know how to correct this thing.

jkruzic's picture

Two postdoctoral positions in Mechanics of Materials at Oregon State University

We are seeking to fill two postdoctoral scholar positions at Oregon State University. The ideal candidates will have expertise in one or more of the following: computational materials science, granular mechanics, solid mechanics, and/or mechanical testing of materials. Positions will initially be for 1 year with an anticipated starting date of January 1st, 2015, with the possibility to continue for a second year depending on performance and continued funding.

The successful candidates will:

Research Associate in 4D Image based quantification and simulation

An excellent opportunity to work in a world leading team with privileged access to facilities that most researchers can only dream about.

Experienced Researcher Fellowship / Post Doc position - Characterisation of powder properties using DEM (IPROCOM)

VACANCY

TECHNOLOGY CENTRE – CHILTON

 

Experienced Researcher Fellowship /
Post Doc position - 
Characterisation
of powder properties using DEM
.

Marie Curie Initial Training Network – IPROCOM

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