I want to apply cyclic load on the blade to inspect it under fatigue loading.
I want to save the blade and I do not want to causes failure to it.
I'm looking for a methodology that can help me in estimating the number of cycles to failure by certain applied cycles.
I think fatigue life test in general is a destructive test. If you are interested in obtaining experimental values , I think you should proceed till obtaining the required no. of cycles then stop, If the blade persists I think this means that the test is successful.
Dear Ahmed,
I agree with that but my question is about any methodology that can help me in extrapolate and find the failure number of damage cycles without experimentally reaching it.
Dear Nihad,
Numerical solutions need experimental verification , and this may cause the blade to fail and this is not my objective.
You want to have estimations under some conditions ?
So i think you could select two or three benchmark models in the field (finit element, petri network...) to simulate your issue then estimate an average life/model. Then you can use accelerated life models whith moderation to narrow your model
Dear Ahmed, your question is not simple...But some possibilities may be opened if we are monitoring the precursors of failures. In particular, first signs of failure beginning we may listen (so called acoustic emission of prelimenary stage of failure) before visual cracks and other defects. My be this method will suitable for you?
Best wishes, Serge
The answer to your question is yes, and you won't even need to load the blade once. The prerequisite is that you have some materials information and a knowledge of the blade construction.
See GL-DNV standard on the design of wind turbines (http://www.gl-group.com/assets/img/flags/Design_and_maufacture_of_wind_turbine_blades_offshore_and_onshore_wind_turbines.pdf ). Possibly appendix H among other may be useful.
If you do not have a knowledge of the material fatigue performance, you may start with something like what is suggested in:
Cornelia E. Demers (1998), Tension-tension axial fatigue of E-glass fiber-reinforced polymeric composites: fatigue life diagram, Journal of Construction and Building Materials.
Fatigue of composites is an active research topic and to my knowledge, a method that allows to predict fatigue life of a structure based on the application of a few cycles is not yet available.
Best Regards,
- Badges
- Science topic
- Similar topics
- Social Psychology
- Attitude