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Crystal plasticity

Post-doctoral position in mesoscale plasticity

The Materials Theory Group at the School of Materials Engineering of Purdue University has a post-doctoral opening in the area of Mesoscale Plasticity of Irradiated Crystalline Solids. The postdoc will use discrete and continuum dislocation dynamics to investigate the deformation and fracture of structural alloys for fusion applications. A background in continuum mechanics and crystal plasticity is required for this position. The ideal candidate is one who is strongly interested in the fundamental aspects of deformation and fracture of metals and alloys and related computational modeling, and must have excellent programming skills in Fortran and/or C++. For inquiry about this position, please send an email to Professor Anter El-Azab (aelazab@purdue.edu).Any interested candidate may send a resume with list of publications, half a page statement of research interests, and the names of two or three references to the email above. The Materials Theory Group performs theoretical and computational research in the areas of mesoscale plasticity and dislocation dynamics, radiation effects in materials, microstructure evolution, thermal transport, and computational methods for materials science and mechanics.

The position is open now until filled.

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.

Post-Doctoral Position in Mesoscale Plasticity of Irradiated Alloys

The Materials Theory Group at the School of Materials Engineering of Purdue University has a post-doctoral opening in the area of Mesoscale Plasticity of Irradiated Crystalline Solids.

The postdoc will use discrete and continuum dislocation dynamics to investigate the deformation and fracture of structural alloys for fusion applications. A background in continuum mechanics and crystal plasticity is required for this position. The ideal candidate is one who is strongly interested in the fundamental aspects of deformation and fracture of materials and related computational modeling, and must have excellent programming skills in Fortran and/or C++. The Postdoc will interact with our group members and with our collaborators outside Purdue: Professors Grethe Winther and Henning Poulsen at the Technical University of Denmark who are performing synchrotron measurement of dislocation structures in deformed metals (see related research at https://pmp.dtu.dk/).

For inquiry about this position, please send an email to Professor Anter El-Azab (aelazab@purdue.edu). Interested candidates can send a curriculum vita with list of publications, half a page statement of research interests, and the names of two or three references to the email above.

The Materials Theory Group performs theoretical and computational research in the areas of mesoscale plasticity and dislocation dynamics, radiation effects in materials, microstructure evolution, phase field method development, phonon and electron thermal transport in crystalline solids, and computational methods for materials science and mechanics.

All qualified individuals, including diversity candidates are encouraged to apply.

mkasemer's picture

PhD Position, Crystal Plasticity / X-ray Diffraction, The University of Alabama

The Advanced Computational Materials Engineering Laboratory (ACME Lab: https://acmelab.ua.edu) in the Department of Mechanical Engineering at The University of Alabama is seeking candidates for a fully-funded PhD position in the area of deformation mechanics to begin August 2022.

WaiChing Sun's picture

Computational/machine learning mechanics Postdoc/PhD position available at Columbia University

Dear colleagues, 

There is a new opening for one postdoc/PhD student position, to be filled immediately, in my research group in the Department of Civil Engineering and Engineering Mechanics at Columbia University. We are looking for postdocs/PhD in the broad area of computational mechanics. Candidates should have expertise and experience on modeling dynamic responses of path-dependent materials and software development. Our project is specifically focused on applications of machine learning for computational plasticity and damage. 

mkasemer's picture

PhD Position - Computational Crystal Plasticity

The Advanced Computational Materials Engineering Laboratory (ACME Lab), in the Department of Mechanical Engineering at The University of Alabama is seeking qualified candidates for an open PhD position. This position is open to US citizens only.

Postdoc vacancy (2.5 years) on multi-scale modelling of fatigue in 3D printed metals

The use of 3D printed metal structures is taking a very fast ramp-up in industry. General Electric has demonstrated the possibility of printing titanium fuel injectors for their LEAP engine, EADS has printed a nacelle hinge bracket for the Airbus A320, Boeing is printing plastic inlet ducts for high-altitude aircrafts, hip implants and other prosthetics are exploiting the design freedom of additive manufacturing (AM),...

How to determine the reference rate of shearing and rate sensitivity for power-law rate dependent crystal plasticity formulation?

In single crystal plasticity, the material strain hardening is specified by the slip system strain hardness which is determined from the strain hardness function (Eqn 1, see attached). Its parameters can be determined by fitting the equation to the experimental stress-strain curve.

Two funded PhD positions at the University of Western Ontario, Canada.

 

We have two funded PhD positions and we are looking for talented, self-motivated, and enthusiastic students with a BSc or MSc degree in mechanical or materials engineering. Students with strong background in crystal plasticity and computational mechanics are recommended to apply.

 

Input file for the Single crystal plasticity subroutine Nonlinear Finite Elements for Continua and Structures by Ted Belytschko

Can anyone provide me with the input file for the example shown in the book Nonlinear Finite Elements for Continua and Structures by Ted Belytschko et al? The poly-slip, rate-dependent, single crystal plasticity VUMAT subroutine that is available publicly is attached in the following link. I have been trying to reproduce the results in Fig. 13.11 to Fig. 13.13. in the book, but am not successful in doing so. Can anyone please provide me with a working example input file for the problem?

https://gofile.io/d/xI9QSV

Input file for the CPFE VUMAT in Nonlinear finite elements for continua and structure

I am learning crystal plasticity and its implementation as VUMAT subroutine from the book Nonlinear finite elements for continua and structure. I am aiming to gain more insight about the implementation by studying the poly-slip, rate-dependent, single crystal plasticity subroutine provided in the solution manual.

However, I couldn't reproduce the example in the book successfully, as I believe I have made errors in defining the material properties in the Abaqus input file. So, can someone please provide the input file for the associated VUMAT subroutine?

How to include temperature effects on the shear rates in Dr. Huang's crystal plasticity code

I am using Dr. Huang's crystal plasticity code for an adiabatic process where temperature increase due to deformation need to be calculated. Dr. Huang's CP UMAT code does not consider the temperature effect of shear rate or hardening. Is there a way to include temperature effects in the current UMAT code?

http://www.columbia.edu/~jk2079/Kysar_Research_Laboratory/Single_Crystal...

Jason Mayeur's picture

Research Assistantship Positions Available in Multiscale Materials Modeling at the University of Alabama in Huntsville

Positions are available in Dr. Jason Mayeur's research group in the Department of Mechanical and Aerospace Engineering at the University of Alabama in Huntsville. Preferred candidates will have earned an MSc degree in Mechanical Engineering or a closely related field, and have a solid background in theoretical and computational mechanics. Ideal candidates will also have prior experience in finite element modeling and computer programming.

Applicants should directly contact Dr. Mayeur:
jason.mayeur at uah.edu    

Timothy Truster's picture

Two open PhD positions in multi-physics process and performance modeling of alloys at the University of Tennessee

We have two open PhD position starting in the Fall semester 2020 at the Computational Laboratory for the Mechanics of Interfaces at the University of Tennessee - Knoxville (http://clmi.utk.edu). First research topic centers upon the modeling of texture evolution during processing (e.g. cogging and rolling) of titanium alloys using crystal plasticity and Fast Fourier Transform methods to couple the mesoscale and specimen scale.

Open Position at A*STAR in Singapore: Research Scientist (IHPC)

The Institute of High Performance Computing, part of A*STAR in Singapore, is seeking a talented, motivated researcher to hire with extensive experience in computational mechanics:

WaiChing Sun's picture

Postdoc position available at Columbia University in the City of New York

We have one or more postdoc positions available, to be filled immediately, in my research group. We are looking for postdocs in the broad area of computational mechanics.  Candidates should have expertise in modeling dynamic responses of path-dependent materials. Our project is specifically focused on the development and validation of multiscale models for energetic/porous/polycrystalline materials across length scales. More details will be provided to interested candidates. 

rajan_prithivi's picture

Critical porosity in the fatigue of additively manufactured IN718 via crystal plasticity modeling

https://doi.org/10.1016/j.matdes.2018.04.022

Highlights

1. Critical porosity is estimated in additively manufactured IN718 via crystal plasticity.

2. Porosity is characterized using high resolution tomography.

3. Non-local damage indicator parameters identify the location of fatigue crack initiation.

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