ENAC Seminar Series by Dr. Nicholas Anton Collins-Craft
Event details
| Date | 16.05.2023 |
| Hour | 16:00 › 17:00 |
| Speaker | Dr. Nicholas Anton Collins-Craft |
| Location | |
| Category | Conferences - Seminars |
| Event Language | English |
16:00- 17:00 - Dr. Nicholas Anton Collins-Craft
Postdoctoral researcher, Centre Inria de l'Université Grenoble Alpes
Non-smooth mechanics for fracture propagation in geomaterials
Modelling fracture propagation accurately and efficiently is a critical issue across a wide variety of engineering disciplines,not least in brittle materials such as rock masses or permafrost. Of the wide variety of modelling techniques, cohesive zone models are the most accurate, but are also correspondingly very numerically demanding. Intrinsic cohesive zone models are the most popular, but their initial elasticity leads to a range of non-physical behaviours that also cause severe numerical difficulties. While extrinsic cohesive zone models should avoid these behaviours, in practice almost all models exhibit the same pathologies as intrinsic models under complex loading such as impact by rockfalls. We use the techniques of non-smooth mechanics to formulate an extrinsic cohesive zone model for mode I (opening mode) cracks that avoids entirely the pathological behaviours under all loading conditions, while also including contact behaviour in the formulation. After re-framing this model in dynamics, we are able to write the system as a linear complementarity problem (LCP). We show that this LCP is well-posed for quite large time-steps, and we are able to benefit from the efficient solution algorithms developed for this class of problem. Some representative examples are explored with the model. We then pass to another model, this time for both mode I and mode II (sliding mode), while including contact and Coulomb friction. This model once again avoids the pathological behaviours characteristic of other models, and the dynamic formulation can be written as an LCP. We can show that the solution of this LCP exists, and once again benefit from the efficient solution algorithms to examine some representative examples. Finally, we examine some prospects for future extensions of this work, the difficulties to overcome, and some applications to a variety of geomechanical problems.
Short bio:
Dr. Nicholas Collins-Craft obtained his Bachelor of Engineering in Civil Engineering with First Class Honours and the University Medal from the University of Sydney in 2014. Starting in 2015, he undertook a joint PhD between the University of Sydney and ´Ecole nationale des ponts et chauss´ees, supervised by Professors Itai Einav, Jean Sulem and Ioannis Stefanou, focused on the modelling of localisation in crushable granular media. This thesis was defended in November 2019. Following this, he undertook a postdoctoral period in the TRIPOP team at Inria Grenoble, working with Drs Vincent Acary and Franck Bourrier, adapting techniques from non-smooth mechanics to the modelling of fracture. Since September 2022, he has been a Marie Sk lodowska-Curie Actions postdoctoral fellow, on a joint project between Inria Grenoble and WSL/SLF Davos, working with Drs Vincent Acary and Franck Bourrier and Professor Johan Gaume, on the topic of climate-change induced gravitational hazards.
Postdoctoral researcher, Centre Inria de l'Université Grenoble Alpes
Non-smooth mechanics for fracture propagation in geomaterials
Modelling fracture propagation accurately and efficiently is a critical issue across a wide variety of engineering disciplines,not least in brittle materials such as rock masses or permafrost. Of the wide variety of modelling techniques, cohesive zone models are the most accurate, but are also correspondingly very numerically demanding. Intrinsic cohesive zone models are the most popular, but their initial elasticity leads to a range of non-physical behaviours that also cause severe numerical difficulties. While extrinsic cohesive zone models should avoid these behaviours, in practice almost all models exhibit the same pathologies as intrinsic models under complex loading such as impact by rockfalls. We use the techniques of non-smooth mechanics to formulate an extrinsic cohesive zone model for mode I (opening mode) cracks that avoids entirely the pathological behaviours under all loading conditions, while also including contact behaviour in the formulation. After re-framing this model in dynamics, we are able to write the system as a linear complementarity problem (LCP). We show that this LCP is well-posed for quite large time-steps, and we are able to benefit from the efficient solution algorithms developed for this class of problem. Some representative examples are explored with the model. We then pass to another model, this time for both mode I and mode II (sliding mode), while including contact and Coulomb friction. This model once again avoids the pathological behaviours characteristic of other models, and the dynamic formulation can be written as an LCP. We can show that the solution of this LCP exists, and once again benefit from the efficient solution algorithms to examine some representative examples. Finally, we examine some prospects for future extensions of this work, the difficulties to overcome, and some applications to a variety of geomechanical problems.
Short bio:
Dr. Nicholas Collins-Craft obtained his Bachelor of Engineering in Civil Engineering with First Class Honours and the University Medal from the University of Sydney in 2014. Starting in 2015, he undertook a joint PhD between the University of Sydney and ´Ecole nationale des ponts et chauss´ees, supervised by Professors Itai Einav, Jean Sulem and Ioannis Stefanou, focused on the modelling of localisation in crushable granular media. This thesis was defended in November 2019. Following this, he undertook a postdoctoral period in the TRIPOP team at Inria Grenoble, working with Drs Vincent Acary and Franck Bourrier, adapting techniques from non-smooth mechanics to the modelling of fracture. Since September 2022, he has been a Marie Sk lodowska-Curie Actions postdoctoral fellow, on a joint project between Inria Grenoble and WSL/SLF Davos, working with Drs Vincent Acary and Franck Bourrier and Professor Johan Gaume, on the topic of climate-change induced gravitational hazards.
Practical information
- General public
- Free
- This event is internal
Organizer
- ENAC
Contact
- Clivia Waldvogel & Sarah Feller