I am doing my FEA project for machining. As far as I know, holistically, after some stages (transient state) when our field variable graph acts with a little range of change we achieve the steady state answer. But there are some vague points to me:
1- The first one is about "determination of transient and steady state cutting simulation" I mean, Is there any relationship for recognition of the steady state condition? for example, a certain amount of time and so on. OR, is there any certain tolerance for change?
2- How I can set the total time for my simulation? I mean, if I want to work with time increment, lagrangian formulation re-meshing, how I can set my general simulation duration?
thanks for your time.
In relation to the point two, you need to know the feed speed of process to define a total time for your simulation.
Feed speed is, for example in turning, the feed (mm/v) x rpm (number of revolution per minute).
Dear Daniel Martinez Krahmer,
Thank you for your reply.
For a certain amount of feet rate, how these parameters could be connected? ( let's take it: 0.2 mm/rev OR in the case of number of revolution 375 Rev/min)
P.S: We can find the total time of cutting a 2D-sample: the length of the workpiece/ cutting velocity. So, I think it is better to clarify my inquiry like this:
How to select the appropriate length of the workpiece in 2D cutting FEM Simulation?
The feed speed is equal to: 0,2 mm/rev x 375 rev/min = 75 mm/min, then, the tool moves 75mm of length each minute or 1,25 mm/s.
I think if you take 5mm to 10mm you have an good simulation process.
Attach you have a little video made by Third Advantage. In this case, the video have 2-3 seconds.
Dear Dr. Daniel Martinez Krahmer,
I really appreciate you and I think, I got your idea. Actually, it is required to verify different feed rate with the other researcher. Therefore, I was wondering about formula or practical solution to choose the suitable length like what you already said (5-10mm).
I.e. how did you decide to choose 5-10 mm for the length of this (75mm/min) case?
Tons of thanks.
Hi Sajad. If the tool move in relation to the material at rate of 75mm/min = 1,25mm/s , then, (5 to 10) mm are equivalent in time to (4 - 8) s.In this sense, I think that this time quantity is good for reproduce the machining process.
thank you all
I found a few approaches with strong resources:
1- 2-3 mm of the chip
2- 4 MiliSec.
3- length> 5* Feed rate
4-length> 20* undercut chip thickness
Well, you have to do a sensitivity analysis to know when will the cutting simulation reach steady state. let's say you are doing a 2D model so you would start with a 2mm workpiece for example. Run your simulation for a step time calculated as length of WP/ cutting speed. To judge steady state you need to look at temperatures generated in the primary, secondary and tertiary zones. If they vary a little from each time increment to the next then you have reached steady state.
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