Inside the mind of a brilliant engineer, Keynote Speech from the Buckling Colloquium in Berlin 2024

[@hnrwagner]

The Python Scripts for the Tower Analysis can be found here: github.com/hnrwagner/Round_Robin_Wind_Turbine_Tower

[@DrMarcSeidel]

Really good presentation from Adam - anyone working with shell buckling should watch this!

[@mikeb1097]

Great presentation from Dr Sadowski, thanks for posting. One thing I note from this and the referenced round-robin papers is that the sources of imperfection are LBA and weld depression and that no comment was made on using GNA as imperfection pattern. Have you any thoughts on using GNA as a source of imperfection for shells? I would have thought that the dimple patterns produced by GNA are much more onerous to the GMNIA than the ripples typical of LBA.

[@hnrwagner]

Not really sure what you mean with GNA as a pattern? As far as I know I was the only one who used Dimple imperfections in the round-robin. I think it will take some time for others to adopt it as well.

[@mikeb1097]

@@hnrwagner prEN 1993-1-6 has the wonderfully vague clause that "The pattern of the equivalent geometric imperfections should be chosen in such a form that, under the defined loading condition, it has the most unfavourable effect on the imperfect elastic-plastic buckling resistance ratio of the shell." While LBA often produces these small rippling/corrugation patterns in axially compressed shells, GNA will produce an actual dimple towards the inside of the shell - at either the maximum load or after the snap-back. The GNA displaced shape can then be scaled so that the magnitude of the dimple complies with the dimple imperfection amplitude δ0,eq. This GNA dimple (combined with any weld depression shapes) corresponds with how the GMNIA actually wants to collapse much better than LBA and in my experience will result in a lower RGMNIA.

[@hnrwagner]

@@mikeb1097 Probably because using the GNA deformation field as an imperfection pattern is not that easy to implement, I know vaguely how to do it. I would directly induce a single dimple by either a small force or displacement and then scale the amplitude until the minimum LPF is found, that works very well in my experience, and also correlates well with test data.

[@hnrwagner]

GNA-based imperfections were not mentioned because they are rare, more difficult to calibrate than LBAs and indeed no-one in the RR used them. They can however be a good basis for a damaging imperfection model, but rather than being used directly they are best 'processed' to extract the features of nonlinear deformation that actually matter. An example of what is meant may be found here: dx.doi.org/10.1016/j.ijsolstr.2012.11.017. However, GNAs like LBAs most likely do not relate at all to any real imperfections caused by real manufacturing processes.

[@CP-zi3eg]

Great video. Thank you for sharing it

[@hnrwagner]

Reference: www.sciencedirect.com/science/article/pii/S135063072300078X Time codes: 0:00 - Introduction 4:30 - International Shell Buckling Exercise 9:30 - World map and participants 10:40 - FEM Mesh Study and Results Evaluation 15:00 - Linear Elastic Analysis Study and Results Evaluation 17:00 - Linear Buckling Analysis Study and Results Evaluation 21:50 - Nonlinear Material Analysis Study and Results Evaluation 26:30 - Linear Buckling and Nonlinear Material Analysis - Why we do it? 29:45 - Nonlinear Material and Geometry Analysis Study and Results Evaluation 32:30 - Comments by Dr. Wagner on GMNA Postbuckling 34:45 - Nonlinear Buckling and Imperfections 37:30 - Result Overview 39:45 - Interpretation of imperfection amplitudes 43:05 - Eigenmode Imperfections and its Problems 47:52 - Buckling Design using Capacity Curves

[@ForensicCats]

Your not monetized, I was going to send you coffee money. Thanks for sharing.

[@hnrwagner]

Hey, what do you mean with I am not monetized? What is coffee money?

[@ForensicCats]

​@@hnrwagner a donation and I could not find your KZbin link that allows for donations. Perhaps check your settings and it should appear under the title once it is working.

[@hnrwagner]

@@ForensicCats I am working on a full model of the TITAN sub and want to compare it with ABC News Implosion Animation, hope its ready in may, we could do a live stream for it and exchange thoughts, what do you think?

[@tvnkap4291]

Please how can i contact YOU?

[@hnrwagner]

can can contact me here, also on my KZbin page you can find my Email adress