Computational Biomaterials and Biomechanics (PAHR)

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Hofi
Beiträge: 107
Registriert: 07.11.2010, 11:23

Computational Biomaterials and Biomechanics (PAHR)

Beitrag von Hofi »

Dear reader,

I splitted this post up in 2 parts. The part of Pahr and the part of Hellmich. Both will hold lectures in this course in which you have to hand in a report each and go to the exam of them. So let`s start with Pahrs Part:

EXAM QUESTIONS of 2015.01.26:


Group A:
  • Draw all boundary conditions and their relationship to the effective Compliance tensor.
  • Pros and Cons of clinical homogenized Finite Elements.
  • How do you get the Orientation of trabecular bone? How can you measure BVTV?
  • Write down the Hill Equation (simple form) and explain it.
  • Say something about the image processing steps: alignemend, extraction
Group B:
  • What are typical finite Elements in Biomechanics? What are there characteristics?
  • Write down the equation for the powerlaw, sketch and explain it.
  • You got an sample picture form a bone biopsy. How can you change the resolution of the image and define the size of the image?
  • KUBC: Write down the equation and name the variables.
  • Pros and Cons of a micro Finite Element study of a Full bone.
  • Sketch the flowchart for the homogenization and also write down the input/ output variables.
As you see it had been 5 questions per group. Time passes by fast, so keep the answers simple.

Report:
  • A group of 3 students has to work together to create a FE- model from the files Pahr gave them. Medtool will be used therefore.
    Be aware that you should download medtool AND anaconda. IF you dont have anaconda running on your PC, medtool will open but when you want to start a mic, it keeps running for eternity (and beyond) doing nothing. [Cause there is no phyton to tell medtool what to do...]
  • Additionally check the ccx and cgx by going into the installation folder and click on ccx.exe and cgx.exe . Usually it will show which files are missing if there is a problem. In my case it had been two .dll- Files I downloaded from the web and then everything worked out fine.
Now the program should run on your PC...

Attached you will find the files needed to get the right results (xml-file, FE_main.inp and apriori-Strain). Just copy them in your working directory, do as described below, you might want to change the input in the Image Processing step and that's it. You have solved Pahrs example.
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Zuletzt geändert von Hofi am 27.01.2015, 21:26, insgesamt 2-mal geändert.

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Hofi
Beiträge: 107
Registriert: 07.11.2010, 11:23

CBMBM (PAHR-2): Old reports (1)

Beitrag von Hofi »

In this post you will find some old reports for reference purposes.
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Hofi
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Registriert: 07.11.2010, 11:23

CBMBM (PAHR-2): Old reports (2) & MATLAB for POWERLAW

Beitrag von Hofi »

And one more post with another report and additionally the MATLAB file for comparing different boundary conditions using the powerlaw.

That should be all you need for the part of Pahr so far. When I finish (or even start) the Hellmich part, I'll post the stuff here too in a similar fashion.

Have fun with it. Hope it helps.

best,
Hofi
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Rieke
Beiträge: 1
Registriert: 25.02.2015, 14:00

Re: Computational Biomaterials and Biomechanics (PAHR)

Beitrag von Rieke »

Danke für das Posten von den Prüfungsfragen für den Pahr Teil :)
Bei der Frage "How do you get the Orientation of trabecular bone? How can you measure BVTV?" Gruppe A
Was ist richtig für den ersten Tei? a) ray field is passed through model, various star directions are considered, Mean Intercept Length is computed oder komme ich über b) "Localization Problem" (crop RVE,...6 unit load cases) zu meiner Antwort?

Was will er bei der Frage "You got an sample picture form a bone biopsy. How can you change the resolution of the image and define the size of the image?" hören? Kurz das Image Processing mit den Filtern erklären und Modelling mit der Geometrie und BCs? Pre-Processing Aspects oder Localization Problem?

Falls sich jemand die Tage noch zusammensetzen möchte, einfach melden :D

LG

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_Hofi_
Beiträge: 24
Registriert: 29.01.2015, 19:04

Re: Computational Biomaterials and Biomechanics (PAHR)

Beitrag von _Hofi_ »

War wer beim zweiten Prüfungstermin? Ich hab Nachtrag am Mittwoch und bräuchte die Fragen ;)

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_Hofi_
Beiträge: 24
Registriert: 29.01.2015, 19:04

Re: Computational Biomaterials and Biomechanics (PAHR)

Beitrag von _Hofi_ »

Hey,
Die Fragen heute waren eine Kombination aus der A und B Gruppe aus dem ersten Test (nur mit umgeschriebenen Fragen). :mrgreen:
Nur einen unterschied hats gegeben, und zwar wurde eine Frage gestellt wie die Auswirkung der Proben größe (4-10mm) aussieht (sketch) in Bezug Youngs Modulus.

Die Antwort wäre die Skizze nach den BCs, also stiffness/RVE_size Diagramm, nur halt invertiert (da E-Modul= 1/stiffness).

bjorgheidur
Beiträge: 2
Registriert: 13.01.2016, 14:55

Re: Computational Biomaterials and Biomechanics (PAHR)

Beitrag von bjorgheidur »

Additional questions from today's exam:
What are the fields of Biomedical Engineering used in this course? (2pts)
What are the main components of an input file? (2pts)
What is morphological closing (2pt)
Total no. of points was 20.

:D

tola99
Beiträge: 102
Registriert: 28.03.2012, 16:24

Re: Computational Biomaterials and Biomechanics (PAHR)

Beitrag von tola99 »

Has anybody the elaboration of the questions which he/she could share? would be very thankful, so thanks in advance!

LG

Caroline Hammoutene
Beiträge: 1
Registriert: 11.11.2015, 12:06

Re: Computational Biomaterials and Biomechanics (PAHR)

Beitrag von Caroline Hammoutene »

Hey Guys
Am I getting that right: Pahr asks nearly the same questions every time? I can only find about 13 questions in that forum, or am i missing something? :?:
greetings

tola99
Beiträge: 102
Registriert: 28.03.2012, 16:24

Re: Computational Biomaterials and Biomechanics (PAHR)

Beitrag von tola99 »

regarding the question "draw all boundary conditions and their realtionship to the effective compliance tensor": in the slides there is the sketch of the stiffness tensor (approximately like f(x)=1/(e^x) , so in this case it should be the inverted sketch (approximately f(x)=e^x)if we want to draw the compliance tensor? would you agree with that? and if we want to draw the elastic modulus in comparison to the RVE size it should be the same like the sketch of the stiffness tensor, because these two are proportional?

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