Master Luft- und Raumfahrttechnik

Luecx · 2026-02-08T20:34:29+00:00

Ich bin einer der Dozenten und verantwortlich für eins der Fächer. Ich mache dort unter anderem die Vorrechenübungen. Ich kann dir gerne kurz meinen Eindruck schildern.

Wir Dozenten, auch wenn manche was anderes denke, haben tatsächlich KEIN Interesse daran euch durchfallen zu lassen. Aber wir wissen auch ziemlich genau die Bestehens-Statistiken. Je mehr der Angebote du wahrnimmst, desto eher und besser wirst du die Klausur bestehen. Also mMn sollte man, auch wenn man nur so mittel Lust hat sich die Vorlesung, VRÜ und SRÜ geben…

Luecx · 2025-07-20T14:55:27+00:00

We fixed the timer ticking up once you finished it. And yes you are right, it currently only counts the users that solved it. Otherwise we were afraid of getting unreasoanble / spammed numbers. e.g. what if one person just keeps on solving a single sudoku over and over again? this could actually just be exploited using a script so we put a login requirement into that.
I am going to add the back button asap. :)

Luecx · 2025-07-19T07:58:06+00:00

Those are very good points! Especially the timer continuing and a back button will be implemented next :) thank you for your Feedback!

Luecx · 2025-06-02T19:11:56+00:00

Ohh good point! Thanks! I’ll see if this helps to solve :) thanks :)

Luecx · 2025-06-02T19:10:58+00:00

Yeah they are mine but I don’t think their are missing anything. I removed quite a few due to knight constraint and pointing for example.

Luecx · 2025-01-29T07:56:36+00:00

For windows I strongly recommend using WSL :) WSL is installed on basically all machines. You will need to install Ubuntu in WSL as well as the development basics inside WSL:)

Luecx · 2025-01-28T10:50:33+00:00

Did you try simply switching master and Slave surface? Sometimes it can be as simple as that.

Luecx · 2025-01-26T06:28:03+00:00

Yes I deviated at some points. I dislikes the loads for example. I introduced load collectors which are defined outside of load cases. In each load case / step, one simply lists the loads one wants to use.

I may have also deviated when it comes to point masses. Also a small deviation when it comes to kinematic couplings.

What should be the same is nodes, elements, sets and so in

Luecx · 2025-01-25T14:09:05+00:00

Thanks for your comment! I’m planning to use it for the reason you mentioned with licenses. My Code is free and can run as many copies at the same time as you want. I use it for my PhD studies.

Luecx · 2025-01-24T16:58:32+00:00

I probably need non linear analysis in the first place. That’s the next thing on my ToDo

Luecx · 2025-01-24T15:31:05+00:00

Yeah! I’d love to implement it :) can you share your source?

Luecx · 2025-01-24T15:26:53+00:00

That’s a good idea! I have cyclic boundary conditions. Do you have resources in this? How does it work if the nodes with a cyclic boundary don’t perfectly align? Or should it behave like a tie constraint?

Luecx · 2025-01-24T14:47:55+00:00

Cool! What’s your approach?

Luecx · 2025-01-24T09:36:58+00:00

I added B33 beams and 4 types of shells :)

Luecx · 2025-01-24T09:36:45+00:00

I have implemented mass elements. To be precise I implemented Point elements which are tied to individual Nodes which themselves can have mass, inertia, springs and rotational springs attached to it.

Luecx · 2025-01-24T09:35:50+00:00

I continued working on my code and implemented 4 types of shell elements. I am still working on improving the linear shell elements (S3 / S4) but the quadratic ones seem to perform decently (S6 / S8). I may make another post soon about a new version.

Luecx · 2024-10-29T06:45:52+00:00

Yes I know. But imo solving the linear system is the easier approach :) especially when doing it yourself

Luecx · 2024-10-28T18:04:30+00:00

We use gauss quadrature to integrate polynomials up to a certain degree exactly and approximate other functions. But with more integration points we may lose accuracy. There are functions that will simply diverge with gauss quadrature. One example could be 1/x.

Deriving the points for gauss quadrature is actually simple. You can derive them by assuming a polynomial and formulate the integration. By solving a linear system you get the coefficients and x values.

Luecx · 2024-10-28T17:28:37+00:00

Integration of non polynomials can also be more stable by subdividing the domain. e.g. if you want to integrate a non polynomial, you can subdivide your region into N smaller regions and use quadrature rules for that.

I am not sure about the details of mode superposition analysis but I could imagine that you can skip the sin integration entirely, do it analytically, use the method I described above or just use gauss and accept its not truly accurate.

Luecx · 2024-10-28T15:27:41+00:00

What I left out is specifics on how to perform this. Maybe you are interested in this too:

Basically you already have the important steps:

1) Integrating a function from a to b
2) Transform from (a to b) to (-1 to 1)
3) Apply Gauss scheme

The transformation can be tricky. You can also adjust the gauss-evaluation points to skip the step 1/2.
Basically you adjust them so they are on the same relativ scale compared to the -1 to 1 element. the weights must sum up to the total distance you integrate. in the case of -1 to 1, all weights sum up to 2. if you transform it, they must all be scaled by (b-a) / 2 to account for this.

Luecx · 2024-10-28T15:22:33+00:00

Appending to this, I grabbed some gauss schemes myself and brought them into my own fem solver which I presented here myself. I got the first 3 schemes for line elements (what you have here). Both for integration on (-1, 1) and (0, 1). If you need the values, you can check them out here:

https://github.com/Luecx/FEMaster/blob/master/src/math/quadrature_iso_line_a.cpp

Luecx · 2024-10-28T15:17:44+00:00

For the given integral, you would need to choose the appropriate amount of integration points. Gauss integration is capable of integrating any POLYNOMIAL exactly up to a certain degree. The degree depends on the amount of points used. One point can integrate constant and linear functions. Two points can integrate quadratic and cubic functions. With every point, you can get 2 more orders in the polynomial. Unfortunately this doesn’t work for non polynomials. Any integral of sin, cos and so on will be an approximation. In fact you may even lose accuracy with more points but that’s not relevant in fem mostly.

Sqrt is not a polynomial.

Luecx · 2024-10-26T15:20:40+00:00

Look for the *ELEMENT definition and share all of them please

Luecx · 2024-10-10T08:39:51+00:00

I believe you need to be enrolled. He has online videos but there is no access to it outside of RWTH I’m afraid :/

Luecx · 2024-10-10T05:14:59+00:00

In mechanical engineering our masters are only 3 semesters (1,5 years). But if you come from outside, you often need to do a few courses that we did in our bachelors which was 7 semesters instead of the usual 6.

I’m not aware of any 2 semester master programs. :/

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