Hello everybody,
I am trying to perform a harmonic analysis of a material sample (say a simple 2D plate) with an edge crack in it using 'Ansys R16'. I see that under sinusoidal loading condition, the two crack faces open or close and interpenetrate (after closing which is not possible practically).
1. I believe, stiffnesses of the crack faces change during interpenetration and so the results are not credible anymore.
2. I also cannot define non-linear contact behaviour (between the two crack faces) in a linear (harmonic) analysis.
How do I overcome this problem?
Bigger idea is to fit the frequency response result from the simulation with that of the experimentally determined response.
I am more than ready to provide further information if required.
Thanks in advance for your time. !!
Regards,
Shreeraman S
EDIT : Thanks for all inputs. Solved.. :)
Dear Shreeraman,
the opening and closing of the crack is a non-linear time-dependent process (which for instance typically leads to higher harmonics in the measured signal). Thus, the properties of the system change with time. I believe if you want to include this process in your model you have to perform a transient analysis rather and a harmonic one. Afterwards, you can always transform the results into the frequency domain by means of a Fourier transform, if your measured data is provided as a frequency spectrum.
Dear Dr. Gravenkamp,
Firstly, thanks a lot for your reply. From 'Transient Dynamic Analysis', I understand that we get time-varying response to time-dependent loads. My doubt is,
- I am not sure if this will solve the problem of interpenetration? (impractical)
- Also, I am trying to read more about 'Transient analysis'. Would really appreciate if you could suggest an article or literature that is worth reading (if any).
Thanks once again.
Have a nice day.
Dear Shreeraman Swamynatha,
The field approached by you is very interesting and also vast, so more research can be done in this regard. It's very interesting topic. The following article link may help you for your kind information.
https://www.researchgate.net/project/Mode-I-Fracture-Parameters-Using-Steel-Fibers-in-High-Strength-Concrete.
https://www.researchgate.net/publication/301348952_Licensed_Under_Creative_Commons_Attribution_CC_BY_Investigation_on_Mode_-_I_Fracture_Parameters_Using_Steel_Fibers_in_High_Strength_Concrete
Article Licensed Under Creative Commons Attribution CC BY Investigat...
Assuming that the goal of your study is to determine the extent of crack propagation in your sample for a given dynamic load, I would use the following approach :
1. Perform harmonic analysis of the component without the crack
2. Extract the stresses as a function time in the vicinity of the crack
3. Perform an analytical calculation of the stress intensity factor based on your calculated stresses. If the geometry of your sample is simple, you should be able find a suitable existing formula for the stress intensity factor in say standard BS7910. If not, you could try building a weight function for your geometry.
- Badges
- Science topic