Hello,
I am rather new to the computer aided engineering & design domains and are currently learning the basic techniques how to model, simulate and post-process a model. I learned that the typical pipeline seems to be modelling in CAD -> generating Tet-Mesh -> Simulation using FEM -> Post Process. For design changes, the pipeline is repeated.
Recently, I stumbled across the isogeometric analysis (IGA) method initially proposed by Hughes et al. [1] in 2005, which allows for FEM-like simulation in CAD. This relieves engineers from meshing that can account for up to 80% of development time [2] and shortens the design pipeline/cycle.
Now, many years have passed since 2005 but still the workhorse of computational engineering projects seems to be the FEM. So, I am curious why is IGA not more common in the industry, while it has so much potential? In order to better understand why the situation still is what it is, I would like to read about your opinions.
Lets boil it down to 2 questions:
1) Why is the IGA not more common in the industry?
2) Is the IGA eventually going to replace the FEM?
I would very much appreciate to read about your experiences and opinions :)
Best regards,
Daniel
[1] HUGHES, Thomas JR; COTTRELL, John A.; BAZILEVS, Yuri. Isogeometric analysis: CAD, finite elements, NURBS, exact geometry and mesh refinement. Computer methods in applied mechanics and engineering, 2005, 194. Jg., Nr. 39-41, S. 4135-4195.
[2] COTTRELL, J. Austin; HUGHES, Thomas JR; BAZILEVS, Yuri. Isogeometric analysis: toward integration of CAD and FEA. John Wiley & Sons, 2009.
FEM has extremely long development history from now and the method has been understood well in every sense and every field. Because of this plenty of commercial tools have been developed on the basis of FEM. The versatility and flexibility of these tools are proven in research and commercial applications of diverse engineering fields.
In contrast, new generation techniques including IGA and a group of meshless methods are yet in its development and research phase. Certainly there will be progress in this domain too and in future we may see commercial tools developed on the basis of these techniques...
We can only simulate nonlinear behaviour with the IGA tool. If we need to perform a stiffness analysis or a linear analysis, we can use IGA. However, in practise, the majority of cases exhibit nonlinear behaviour. To the best of my knowledge, there is no IGA tool that can simulate nonlinear behaviour. IGA tools are still evolving to handle complex nonlinear behaviour.
The issue of "verification, validation, and uncertainty quantification" is fundamental to the real-world application of numerical methods to critical applications. ASME has published has published standards for solid mechanics (VVUQ 10) as well as fluid mechanics and heat transfer (VVUQ 20). There are additional VVUQ standards that build upon these for specific needs, such as Nuclear Power (VVUQ 30) and Medical Devices (VVUQ 40). There is one under development for Machine Learning (VVUQ 70) that has nothing directly to do with 10 or 20.
The point is, there is lot that goes into engineering tools before they are accepted for engineering applications. Once it's in the "engineering" world (as opposed to "in development"), it must be good enough to be widely used without the dev team or algorithm designer providing any feedback or guidance. This is part of the issue -- as other have already answered, there are issues of quality control with respect to the use of the software tools.
And no, absolutely no, meshing is not 80% of the time in using FEM. That was vaguely true back when one did manual meshing back in the early 90s for more complex models, but it's not true now. Your question is based on an incorrect premise ... and that is why there is not a market-based drive to make the change to an IGA-pure method you hypothesize.
Novelty has it's place in peer-reviewed work. It's a starting point. You seem to be citing just a single set of authors instead of spending a few minutes looking beyond that using RG or Google Scholar. The thing is, IGA is essentially FEM, just taking it from a different angle (no pun intended). (Article About isogeometric analysis and the new NURBS-based finite e...
)"The goal of integrating computer aided design (CAD) and finite element analysis (FEA) has led to a new computational method called Isogeometric Analysis (IGA). Its main idea is to use the same mathematical description for the geometry in the design (CAD) and the analysis (FEA). Much of the recent research on isogeometric analysis uses Non-Uniform Rational B-Splines (NURBS) as basis functions, as this geometrical representation is the most widely used in engineering design systems. It has been shown that NURBS-based finite elements are very well suited for computational analysis leading to qualitatively more accurate results in comparison with standard finite elements based on Lagrange polynomials. Due to these motivating results, NURBS-based finite elements are currently implemented into LS-DYNA."
Overall ... IGA techniques are growing in popularity and are being folded into existing computational platforms, just a BEM (boundary element method) techniques have. It's not a question of "one size fits all".
I can confirm that meshing is far from being such a pain point as it used to be and it is often done without any manual intervention. It usually becomes costly in areas of very small and complex trimmed NURBS patches, which are only kept watertight by the internal geometric tolerances of the CAD tool. And for exactly those regions, I would at least question the accuracy of IGA.
Moreover, there is a number of other exciting research to handle small geometric features in the model in a stable way, see for example: https://www.cs.cmu.edu/~kmcrane/Projects/NavigatingIntrinsicTriangulations/paper.pdf
https://cs.dartmouth.edu/wjarosz/publications/sawhneyseyb22gridfree-small.pdf
I guess it remains exciting to see to what extent IGA will be establish in the industrial context and what other possibilities will arise besides the road.
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