very valuable information sir, your videos are so helpful. please create a video on fatigue analysis of pressure vessel by Ansys workbench considering elastic-plastic approach.
@@graspengineering9249 I think elastic plastic is much easier than elastic stress analysis as we don't need to do stress linearization and less conservative. it is as simple as evaluating if analysis do converge or not. I eco Mr. Atul comment that it will very much appreciated to do elastic plastic approach including ratcheting assessment. with thanks.
These lectures are very good and very informative. Plz let us know if there is any sponsor page as we will like you to make these lectures. It will be good if you have something on thermal ratchetting or elastic plastic shakedown analysis on Ansys
Hello & Thank you for appreciation ! Thermal ratcheting and elastic plastic can be done as per ASME design by analysis approach with ANSYS tool. We will going to make video on both the topics in in future. Please contact us on graspengineering@gmail.com
Thank you very much for this informative video! Great work.I have couple of questions: 1. Can you please further elaborate (at 31:30) why there is no means stress correction or how mean stress correction is included in the ASME? 2. When linearization is performed why is von Mises stress considered and not max principal? 3. Usually when calculating fatigue, safety margin of min 3 is introduced i.e. final allowable number of cycles N is divided by a safety margin. How is ASME introducing this safety margin? or maybe better question is where exactly is safety introduced in ASME calculation? 4. SN curves are provided in Annex 3-F. How do we know which of these curves correspond to ASME Section II - Materials (Part D)? Also what to do when we have material that doesnt correspond with curves defined in Annex 3-F? Thank you in advance
Hello Filip, please find reply to your question below: 1. For ASME based pressure vessel, for fatigue analysis the material are adjusted for possible mean stress effect hence mean stress correction is not required. 2. The latest ASME code uses von mises stress theory hence von mean stress are used for evaluation. 3. ASME fatigue is different compare to other fatigue evaluation methods. It is based on empirical and experimental data. Hence while following ASME, damage factor is used for fatigue evaluation ( You can calculate safety margin at your end but not required). 4. At the beginning of fatigue curve, the materials are mentioned for which those fatigue curves are used. Mostly all the material are well defined if you are following ASME code while designing too, but if you do not have fatigue curves then you can use analytical formulas to calculate fatigue life as mentioned section Annex 3-f section of ASME. We are planning to do course on ASME design by analysis section (refer our community tab for information). You can join that course to clear all your doubts. Will share link afterword's.
very informative sir.. I have seen screening analysis to be done before fatigue for pressure vessel as per 5.5.2.3. Kindly provide detailed video with example for screening analysis.
Thank you very much for the detailed explanation. Can we apply this methodology to pressure vessels subjected to external pressure? The stress cycle is a rectangular spectrum with a dwell period.
I watched your video and you have shown how to calculate the alternating stress due to pressure change. However, If we have thermal fluctuations.. how do we extrapolate those results ? Do we need to do transient thermal and import the result in static structural to find the complete stress due to thermal or is there any other way of doing it ?
We need to follow the same procedure for thermal too, Alternating stress will develop due to peak temp and min temp conditions for various duty cycle. As mentioned in video for thermal case, we need to calculate separate local equivalent stress range for alternating stress calculations. Regarding analysis you can either do steady state or transient state analysis. If you have transient profile you can do transient simulation, It is more realistic compare to steady state.
Hi, at 36:05 what is the Se = Saltk*Max(Efc/Et,1) calculation? I cant see it in the code. I assume the author is using 5.5.3.2. Once you have the alternating stress, you can calculate damage factor and permissible cycles directly.
When calculating the stress range should you subtract principal and shear stresses individually for each load case and then combined into the equivalent von mises equation?
Hi Sir, Your videos are amazing and very informative. Please tell me when you will start your course as you were needed 100 persons. is it free or paid?
Nice explanation! Do we need to input the cyclic loads in multiple load cases like 200 cycles in ansys (i e consumed cycles) or we just input the one peak and one valley to get stresses?
Sure, if possible will try to upload the seperate video. We are working on PV FEA course there we have included this;; you can subscribe once it is available.
You can use Ncode or ASYS fatigue module or else do hand calculation. Just simulate peak and valley condition in ansys and do postporcessing with hand calculations.
