Compact It Project Granted

It has been very busy weeks, turning into busy months and without noticing, almost a year has passed. The main news is that I got a Academy of Finland project, Compact It, and we still are looking for a researcher who would be interested to take part. Your task will be to use and develop Granular Material Point Method and Uintah software suite, to model dynamic soil exchange. The project will involve close cooperation with Menard and build over resaerch from 2013. You can find the advertisement at Aalto webpage. The position is open until filled. Please apply, I try to check the applications weekly!

Geomeasure project awarded

Would you like to contribute to GEOMEASURE? We are looking for a postdoctoral researcher who would use MPM to model offshore in-situ tests!

File:Gunfleet Sands Offshore Wind Farm - - 2091181.jpg
(c) Ashley Dace, Creative Commons License, Gunfleet Sands Offshore Wind Farm

Academy of Finland has awarded Aalto & Geological Survey Finland consortium financing for the Geomeasure project. We will investigate the Finnish seabed with GTK research vessel Geomari and find new ways to interpret the results of the tests, in particular free fall penetrometer tests. To do that, we will take samples from the seabed and correlate results of experimental testing with the penetrometer data. Also, the tests will be numerically modelled with MPM. We also plan to investigate the behaviour of the deposits under cyclic loading, typical for wind turbines.

Geomeasure webpage

The logos of Academy of Finland, Aalto University and Geological Survey Finland are owned and copyrighted by the Academy of Finland, Aalto University and Geological Survey Finland, respectively, and used here just for informational purposes only.

Review Paper on Material Point Method

Our review paper on Material Point Method is now available here. The link will expire in a month, but I hope that by that time we will be able to provide a copy that could be used instead.

Please have a look, and let me thank all the co-authors: professors Martin Berzins, Will Coombs, Jim Guilkey, Matthias Möller and Kenichi Soga, as well as the doctoral students (some of whom graduated by now): , Tito Adibaskoro, Seyedmohammadjavad Seyedan, Roel Tielen and Quoc Anh Tran (all the names in alphabetical order). Thank you again!

Granular MPM

We got new paper published on Granular Material Point Method in Computers & Structures. We are proud of the paper, where we show how you can get continuous material discontinuous during the flow, and then, continuous again. Thanks to that, we can have the silo filled properly 🙂

Silo filling simulation, Granular MPM
Silo filling simulation, Granular CPDI

Are you interested? We have open positions for a post-doctoral position, open until 14th of June 2021. Contact me for more information, as you will have to show your multidisciplinary approach in the application. Good luck!

Installation talk

I have recently recorded an ‘Installation Talk’ entitled “THMC modelling of bentonite: Nuclear waste repositories safety barriers”. See it below:

In case you found it interesting, and would like to have more information, or collaborate on the subject, please do not hesitate to contact me at my Aalto email, search for Wojciech Solowski, Aalto to find it.

Also, hope all of you will have good time during the coming holiday season and let me wish you all the very best for the New Year 2021!

The Installation Talk has been recorded by Aalto University, as I have been tenured at Aalto and promoted to Associate Professor. Many thanks for all those who were involved!

E-Unsat 2020 presentation and Young Invited Lecture

The E-Unsat 2020 has been excellently organised and a resound success, despite being fully online. Even though I must say I did miss the chats with friends and informal, but often illuminating discussions with the attendees, I still have seen many great presentations and learnt much.

Silo filling comparison, CPDI vs Granular CPDI. Simulation done by inserting points on top, and letting them settle under gravity. Lines denotes the domain of the material points, with significant deformations and lack of density recovery in CPDI simulation, while with granular extension the particles settle down at much more realistic density. We used Mohr-Coulomb model for the simulation, (c) Seyedan & Sołowski

I was also presenting the paper authored by Dr Abed and me on validation of gas transport couplings in our THMC coupled Finite Element Method code Thebes (presentation here, and paper here). We have much more to do in relation to gas transport – my doctoral student Abhishek Gupta is responsible for that, and we hope to deliver ambitious simulations of gas transport of a generic nuclear waste repository in a year or two.

I was delighted to deliver the Young Invited Lecture on Granular Material Point Method, something we are working on with Seyed Mohammad Javad Seyedan. We will aim to publish full paper based on the presentation, but for now, the presentation is here.

Many more exciting things has happened and is happening with the research in my group – I will try to update you on that soon!

Long-delayed update

Hi, I have been very busy recently, leading to lack of updates for a very long time. During past few months I delivered a plenary lecture during the 32nd Nordic Seminar on Computational Mechanics in Oulu (slides), Quoc Anh Tran graduated with a doctoral degree (thesis), and we have a new journal paper published, “A convected particle least square interpolation material point method” in IJNME. That one is not currently freely available, so in case you need a copy, contact me at my Aalto email.

Spectacular train station in Liège, architect Santiago Calatrava

So, what the future holds? SMJ Seyedan should graduate relatively soon with another doctoral degree related to MPM, Tito Adibaskoro is slowly progressing towards the same goal. To continue the research I applied for research related to MPM both at national level (Academy of Finland proposal) and international one (Marie-Curie ITN network), and let’s keep fingers crossed.

On the THMC modelling of clays, a new student has started in January, more update on that later!

Few more presentations…

A statue of a mermaid sitting on a rock, surrounded by water.
Photo: CreativeCommons (author AVDA Berlin), see more

Last month I had a pleasure to give presentations on MPM and modelling of clays at Chalmers University, Technical University of Denmark (DTU) and Hamburg University of Technology (TUHH). The presentations are here for MPM and Clay

Hopefully the cooperation with those universities will be successful and we will get some grants together in the future!

Papers, papers…

Much is happening at Aalto and I have been late with much what should be posted. Just to update things quickly, recently SMJ Seyedan has published a paper detailing a small strain enhancement for constitutive models for soils. The paper is here (open access). The idea is to have a thermodynamically consistent enhancement in the initial part of the stress-strain curve, which can be applied to any model using constant shear modulus. We tested it for Mohr-Coulomb and Modified Cam Clay, but it should work for other constitutive models too. Unfortunately, we have no such neat way to adjust the bulk modulus yet, but hopefully in the future… The paper comes with a Matlab code, so it is easy to try it out!

On another front, QA Tran has published a paper related to the null space errors in the Material Point Method. The paper is here and is also open access. The paper discusses null space errors and show how to filter them out efficiently. Such filtering is recommended when we have a problem with large deformations, in which number of material points in some grid cells increases above the initial value. That creates a problem when the data is tranferred from the nodes back to the material points – we have less nodes than the points and as such the transfer uses extra assumptions leading to errors. For example, having 4 nodes transferring data to 9 points, we need to create 9 values at the points from 4 values at the node – that is impossible without extra assumptions which may lead to errors.
The same paper also shows that use of a generalised-alpha integration scheme in the Material Point Method helps to damp out high frequency vibrations, without affecting the total energy and total momentum balance much. Very useful when we need a solution without high frequency noise – and much better than using an overall damping coefficient which alters the solution significantly.

S. Seyedan and W. T. Sołowski, “Enhancing Constitutive Models for Soils: Adding the Capability to Model Nonlinear Small Strain in Shear,” Advances in Civil Engineering, vol. 2019, Article ID 6016350, 11 pages, 2019.
Tran, Q‐A, Sołowski, W. Temporal and null‐space filter for the material point method. Int J Numer Methods Eng. 2019; 1– 33.

Dragan Grgic public lecture at Aalto, 8th April 2019

Microstructural characterization and numerical evaluation of the effective elastic properties of oolitic rocks

Aalto University has had the pleasure to host a public lecture of Professor Dragan Grgic (GeoRessources Laboratory, Université de Lorraine). Professor Grgic visited Finland due to cooperation with VTT and GTK. During the visit, he kindly agreed to held a lecture at Aalto.

Professor Grgic presentation can be downloaded here.