model broke

[bertin]

Hi,

I have ansys10.0 University intermediate

and I'd like to know how Ansys evaluate when and where my model broke. I have already try to use the functions failure criteria, fatigue and crack but I don't understand how do these function run and the software's help doesn't help me.

And in an other part I wonder whether that is possible to carry out it with the University intermediate license

Thank for your help

best regards

 

[Stringmaker]

Bertin,
I will assume that you have done a static analysis of some sort. To get any real help I think you need to be a little more specific as to the procedure you used to model the subject in question here and tell us what it is exactly. I'm not a guru by any means, but under the Solution Controls did you request that "All Solution Items" be wrote to the results file, setting the Frequency to "Every Nth Substep" (where N is an appropriate number...N=1 would probably make the most sense unless you have an enormous number of substeps)? If so in /POST1 you can view every substep for that particular load step or I believe you should even be able to create an animation of of the events for every substep I believe. However, you'll have to confirm that as I've never done this personally.

-Brian

 

[TGS4]

You're going to have to give us a little more information. What part "broke"? How did it fail? What failure mechanism are you trying to evaluate? Why are you using FEA to evaluate this part?

Also, please note that if you are a student (I'm making an assumption based on you using the University version of ANSYS), then tread carefully and check out

http://www.eng-tips.com/market.cfm

 

[bertin]

Thank you to answer me,

I will try to be more specific. Currently I am developping a thermal microactuator with Ansys and I'd like to know with the stress and the temperature When and which part of my model will broke but I'd like that ansys give me this stress and this temperature with which my model will broke.
For this I use static analysis but I don't understand how run the funtions failure criteria, fatigue and crack/crush and I don't know if it's possible to carry out what I would.

Thank for your help

best regards

 

[Stringmaker]

What are you trying to simulate exactly here? Crack/crush (fracture) is a completely different failure mode than fatigue. I still don't have a clear picture of what is happening and the sequence in which it happens, loads applied, etc. If you look under /POST1 commands you'll find the help section is pretty good about guiding you through a fatigue analysis. The fatigue analysis is not an actual analysis but rather something that uses the results from a static stress run as well as some numbers which you will input. Have you researched the EKILL command at all? You may find this helpful as well depending on how exactly you chose to analyze your model.

Good luck.

 

[TGS4]

bertin,

Before you go ahead and fun an analysis, I think that you need to understand what exactly you are looking for - and I'm talking from a first principles perspective. So, identify your failure modes - all of the ones that you wish to evaluate. Then, understand and appreciate the fundamentals behind each of these failure modes - understand the basic physics behind what's happening and what is causing "failure". Then, treat the FEA as a numerical "experiment". You will need to design this experiment the same way that you would any physical experiment.

My recommendation to you at this time (based on the information that you have posted), is to stay away from the FEA program and figure out what you are trying to discover. Use a "design of experiments" approach to your problem, and once you've done that, please come back to us if you have any specific questions about particular functionalities in ANSYS. We're more than willing to help you - but...

 

[bertin]

Ok sorry if I'm not clearly in my explanations,

In fact, the field in which I work is the microelectronic and I try to carry out a thermal microactuator in silicon. What I would like to simulate it's the lenght of life of my microactuator when he is submit to a voltage level. When I apply a voltage level on my microactuator this one moves and his movements generate stress and temperature and these both parameters will play an important part for the lenght of life of my microactuator. what I want to know it's which part of my microactuator and when will broke in first.

Tahnk for your help and I hope you will understand me now

best regards

 

[Stringmaker]

What you're trying to do I would say can most certainly be done. Since you are dealing with temperature dependent materials this will play a large part in your analysis. I would say the best way to approach your problem (in a general sense) is to perform a thermal analysis and using these results perform a stress analysis. The problem you may run into is that your physical (real life) loads may not be easily placed on an FE model. You may need to make certain assumptions or have some sort of preliminary data which will serve as your inputs. If you can provide a list of loads which are seen during operation and some sort of illustration or model (a picture posted to a website would be great) I'm sure that you would get some great feedback from forum members of how to model your scenario. From an informational standpoint much more is needed.

 

[bertin]

Thank, here below the program of my microactutor, read it ansys with file->read input from:

/TITLE,actionneur
/NOPR
/PMETH,OFF,1
KEYW,PR_SET,1
KEYW,PR_STRUC,1
KEYW,PR_THERM,1
KEYW,PR_FLUID,0
KEYW,PR_ELMAG,1
KEYW,MAGNOD,0
KEYW,MAGEDG,0
KEYW,MAGHFE,0
KEYW,MAGELC,1
KEYW,PR_MULTI,2
KEYW,PR_CFD,0

/PREP7

ET,1,SOLID98

MPTEMP,,,,,,,,
MPTEMP,1,0
MPDATA,EX,1,,169e9
MPDATA,PRXY,1,,0.22
MPTEMP,,,,,,,,
MPTEMP,1,0
MPDATA,DENS,1,,2330
MPTEMP,,,,,,,,
MPTEMP,1,0
UIMP,1,REFT,,,
MPDATA,ALPX,1,,2.9e-6
MPTEMP,,,,,,,,
MPTEMP,1,0
MPDATA,KXX,1,,150
MPTEMP,,,,,,,,
MPTEMP,1,0
MPDATA,RSVX,1,,2.3e-5


!cadre

BLOCK,0,40e-6,0,6e-007,0,200e-6,
BLOCK,740e-6,780e-6,0,6e-007,0,200e-6,
BLOCK,40e-6,740e-6,0,6e-007,0,40e-6,
BLOCK,4e-005,0.00074,0,6e-007,370e-6,410e-6,
BLOCK,0,40e-6,0,6e-007,210e-6,0.00041,
BLOCK,740e-6,780e-6,0,6e-007,0.00021,0.00041,

!actionneur gauche
BLOCK,40e-6,340e-6,0,0.6e-6,190e-6,200e-6,
BLOCK,40e-6,140e-6,0,6e-007,210e-6,220e-6,
BLOCK,140e-6,340e-6,0,6e-007,210e-6,290e-6,
BLOCK,330e-6,340e-6,0,6e-007,200e-6,210e-6,
BLOCK,340e-6,370e-6,0,6e-007,220e-6,230e-6,

!actionneur droite

VSYMM,X,7,11,1,0,0
VGEN, ,12,16,1,780e-6,0,0, , ,1

!poutre

BLOCK,370e-6,410e-6,0,0.6e-6,170e-6,290e-6,
BLOCK,385e-6,395e-6,0,6e-007,290e-6,320e-6,

!trou
BLOCK,176e-6,181e-6,0,6e-007,247.5e-6,252.5e-6,
BLOCK,217e-6,222e-6,0,6e-007,0.0002475,0.0002525,
BLOCK,258e-6,263e-6,0,6e-007,0.0002475,0.0002525,
BLOCK,299e-6,304e-6,0,6e-007,0.0002475,0.0002525,
BLOCK,476e-6,481e-6,0,6e-007,0.0002475,0.0002525,
BLOCK,517e-6,522e-6,0,6e-007,0.0002475,0.0002525,
BLOCK,558e-6,563e-6,0,6e-007,0.0002475,0.0002525,
BLOCK,599e-6,604e-6,0,6e-007,0.0002475,0.0002525,

VSBV, 9,19
VSBV, 27,20
VSBV, 9,21
VSBV, 19,22
VSBV, 14,23
VSBV, 19,24
VSBV, 14,25
VSBV, 19,26

VADD,1,2,3,4,5,6,7,8,9,10,12,13,14,15
VGLUE,11,16,17,18,19

ESIZE,10e-6,0,
VMESH,all



DA,124,UX,0
DA,124,UY,0
DA,124,UZ,0

DA,174,UX,0
DA,174,UY,0
DA,174,UZ,0
DA,174,TEMP,293
DA,174,VOLT,0

DA,172,UX,0
DA,172,UY,0
DA,172,UZ,0
DA,172,TEMP,293
DA,172,VOLT,0

DA,179,UX,0
DA,179,UY,0
DA,179,UZ,0
DA,179,TEMP,293
DA,179,VOLT,10

DA,178,UX,0
DA,178,UY,0
DA,178,UZ,0
DA,178,TEMP,293
DA,178,VOLT,10

DA,22,UX,0
DA,22,UY,0
DA,22,UZ,0