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Plasticity

Ramathasan Thevamaran's picture

Origins of size effects in initially dislocation-free single-crystal silver micro- and nanocubes

We report phenomenal yield strengths—up to one-fourth of the theoretical strength of silver—recorded in microcompression testing of initially dislocation-free silver micro- and nanocubes synthesized from a multistep seed-growth process. These high strengths and the massive strain bursts that occur upon yield are results of the initially dislocation-free single-crystal structure of the pristine samples that yield through spontaneous nucleation of dislocations.

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. 

PhD position(s) in modeling of the interaction between phase transformations and plasticity

PhD position(s) is available for Spring 2022 in the Engineering Mechanics program in Aerospace Engineering Department at Iowa State University to perform theoretical and computational part of work on NSF-funded projects on the interaction between phase transformations and plasticity. Phase-field, micromechanical, and macroscale simulations using FEM are of interest, in close collaboration with high-pressure experiments performed in our lab. Please send vita to Prof. Valery Levitas ( vlevitas@iastate.edu )

Shailendra's picture

Post-doc position in Mechanics of Materials at University of Houston

A one-year post-doc position is available in our research group at the University of Houston with a start date of 1 September 2021. 

We are interested in understanding how microstructural aspects govern material failure. Our approach relies on formulating theoretical frameworks that are informed by experiments and implementing them computationally.

Join us to expand in more novel directions:

(i) Data-driven plasticity and failure;

(ii) Phase-field approaches to plasticity and failure;

PhD opening in Computational Mechanics and Optimisation at University of Technology Sydney, Australia

The project “Computational mechanics and optimisation for energy absorption of materials” is calling for applications for PhD scholarship commencing in 2021. This project is funded by the Australian Research Council Discovery Early Career Researcher Award. Candidates with knowledge and research experience in computational mechanics, design optimisation and machine learning are encouraged to apply.

 

Project description:

Harold S. Park's picture

Postdoc Position in Computational Nanomechanics

I am looking to recruit a highly motivated and independent postdoctoral researcher to study, via the development of new computational methodologies, the deformation mechanisms in crystalline nanostructures.  The specific emphasis is on predicting the plasticity at timescales that far exceed those possible in classical atomistic simulations, and verifying the predictions through collaborations with experimentalists.  The position is available as soon as possible for at least a 1.5-year duration, with possible extension to future years depending on the availability of fundin

Four Fully Funded PhD Positions

#IPPTPAN in collaboration with Department of Engineering at #NTU is offering four fully supported #PhD positions in the following fields:

 

1) Non-linear thermo-mechanical behaviour of polycrystalline shape memory alloys undergoing complex loadings < https://www.ippt.pan.pl/_download/tem_prac_dok/2020_z_kowalewski_en_1.pdf >

 

WaiChing Sun's picture

Computational Mechanics Postdoctoral Research Scientist Position at Columbia University

Dear colleagues, 

There is a new opening for one postdoc 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 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 applications of machine learning (reinforcement learning, graph embedding) for computational plasticity and damage. 

Nanoindentation processes in full view

The microelectronics revolution is one of the most influential drivers of current industrial developments. To probe the mechanical properties of ever shrinking materials and components, nanoindentation has come to be an omnipresent and indispensable method. In a recent combined experimental and computational approach, an international team of scientists was for the first time able to resolve the dynamic atomistic processes taking place at the elastic-plastic transition during nanoindentation.

Jinhyun Choo's picture

Computational Geomechanics mini-symposium at EMI 2020 New York

Dear Colleagues,

We would like to cordially invite you to the Computational Geomechanics mini-symposium at the ASCE EMI 2020 Conference, which will take place on May 26–29, 2020 at Columbia University in NYC. The abstract submission is now open until January 15, 2020 (Link: https://submissions.emi2020.org). The mini-symposium description is given below:

Plane stress Abaqus UMAT

Choose a channel featured in the header of iMechanica: 

Hello everyone,

I have created a UMAT code for J2 elasto-plasticity with isotropic hardening for 3D solid elements.

At this point I would like to support also plane stress shell elements. What changes in the code are

suggested? The already implemented code, takes as input the strain tensor at time tn and the strain

increment tensor and updates the stress at time tn+1 and calculates the material Jacobian and 

achieve quadratic convergence. The stress and strain tensors are manipulated as 6x1 vectors and the 

rbsills's picture

Postdoc Opening in Computational Materials Science at Rutgers University

The microMechanics of Deformation Research Group (mMOD) in the Department of Materials Science and Engineering at Rutgers University is seeking a Post-Doctoral Associate to participate in a pair of collaborative projects with a Department of Energy National Laboratory. The projects are focused on using discrete dislocation dynamics (DDD) simulations to understand dislocation patterning in deformed metals, and molecular dynamics (MD) simulations to understanding crack initiation in hydrogen-affected steels.

WaiChing Sun's picture

Call for Abstract: WCCM Paris Mini-symposium on Computational Geomechanics

Dear colleagues,  We would like to make you aware of a mini-symposium we are organizing for WCCM-ECOMAS in 2020, to be held in Paris on July 19-24, 2020. The symposium is entitled "Computational Geomechanics", and focuses on modeling aspects related to geological materials.

Karol Frydrych's picture

The unknown paper by M. T. Huber

More often than not I find in the books I read the information about the von Mises yield cirterion without mentioning any contribution of Maksymilian Tytus Huber in this field. E. g. I'm reading now "Materials for Nuclear Plants" by Wolfgang Hoffelner. When discussing the yielding conditions of the material he refers to von Mises, Hencky and even to Maxwell, but does not mention Huber. M. T. Huber anticipated to some extent the criterion of Mises already in 1904 (von Mises published his paper in 1913), but is not recognized by most of mechanicians.

PhD position: High rate behaviour and fragmentation of printed metals

 

Open PhD student position

Research topic: Multiple localization and fracture in printed metallic rings subjected to dynamic expansion

Research project: ERC starting grant - PURPOSE

Institution: University Carlos III of Madrid (Spain)

 

Stress update scheme in platicity

Hi everybody,

I am studying the plastic deformation of sheet metal. Recently, I study about stress update scheme in finite element analysis using return mapping method. For this problem, we can calculate the increment of stress components, Δσ for a given value of strain components Δε using elastic predictor - plastic correct scheme. Since Δε = Δεe +Δεp, first, we assume Δεp=0 and check the yield criterion. Then, we find Δεp to satisfy the yield criterion as well as the consistent condition.

However, I have a question as the follows

Jinhyun Choo's picture

Computational Geomechanics mini-symposium at EMI 2019 Caltech

Dear Colleagues,

 

We would like to cordially invite you to the Computational Geomechanics mini-symposium in EMI 2019, which will be held on June 18–21, 2019 at Caltech, Pasadena, CA, USA. The abstract submission is now open at emi2019.exordo.com until January 30, 2019. The mini-symposium description is given below:

 

EMI 2019, June 18–21, 2019. Caltech, Pasadena, CA, USA.

(Joint conference with Geo-Institute)

 

Amit Acharya's picture

Plasticity implies the Volterra formulation: an example

 A demonstration through an example is given of how the Volterra dislocation formulation in linear elasticity can be viewed as a (formal) limit of a problem in plasticity theory. Interestingly, from this point of view the Volterra dislocation formulation with discontinuous displacement, and non-square-integrable energy appears as a large-length scale limit of a smoother microscopic problem. This is in contrast to other formulations using SBV functions as well as the theory of Structured deformations where the microscopic problem is viewed as discontinuous and the smoother plasticity formulation appears as a homogenized large length-scale limit.

Emilio Martínez Pañeda's picture

Crack Growth Resistance in Metallic Alloys: The Role of Isotropic Versus Kinematic Hardening

We have always modelled crack propagation under monotonic/static loading in metals assuming isotropic hardening. However, we show that anisotropic/kinematic hardening effects play a significant role due to non-proportional straining with crack advance; the isotropic hardening idealization leads to steady state fracture toughness predictions that could be 50% lower. I hope that some of you find this work interesting.

Emilio Martínez-Pañeda, Norman A. Fleck. Crack Growth Resistance in Metallic Alloys: The Role of Isotropic Versus Kinematic Hardening. 

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