Pipe bending simulation


#1

Dear All,

I would like to do a simulation as described:

there is a 2 point support system, and a tube we want to bend with the top cylinder moving down then hold the load then release for a bit, and again this cycle until it passes plasticity (simulating fatigue in the same time),
using the time and force is given in a table.
please see attached load and time chart for more understanding.

I was able to set up this layout for static analysis and with 1 load, but was not able to do it for dynamic analysis.
or shall I use static simulation
with -non linear analysis ?

https://www.simscale.com/projects/tenshinshoden/pipe_bending_2/

thanks a lot,

Regards,
Richard


#2

dear @jousefm , you did many ‘similar’ simulations.

many thanks for your time :slight_smile:


#3

Hi @tenshinshoden!

You could do a .csv upload of your load over time sheet and do a nonlinear static analysis if you like - that should work.

I am tagging @BenLewis, @cjquijano and @ggiraldo here, maybe they can give you some more input.

Best,

Jousef


#4

Bruno kindly helped me to set up the simulation, but it is not working with ‘the load over time table’


#5

Hi,
Could you link here the latest project that @bdelatti shared with you, so we do not need to start from scratch?
Best,
Richard


#6

Hi,

This is my replica of his help but put the time dependent load on it

https://www.simscale.com/projects/tenshinshoden/pipe_bending_3/

Thanks


#7

Hi @tenshinshoden,

I took a quick look at your setup and I noticed two things.

  1. Your running a Static analysis so time is not relevant (think of it more as solution steps not actual time). Your simulation runs from 0 to 1 with .1 time step. Your load table goes from 0 to 214. One issue is that the table can not have a 0 time in it, but the other issue is that your simulation is over before any load is really applied. I modified you table as shown below and then I ran the simulation from 0 to 8 with a step of .5.

  1. The other issue I saw is when the solution starts, initially the pressing rod is unstable. I added an elastic support to this part.

Let me know if this helps at all.

Good Luck!
Christopher


#8

Hello @cjquijano,

Many thanks for the reply. Will have a look at it tonorrow

So how could I simulate the Time-load diagramm stated in the first post?

Thanks

Richard


#9

Hi @tenshinshoden,

If you need to run the loading for 214 seconds then your only option will be a Dynamic analysis. I am not sure what you will gain when you are just sitting at each load for 30-45 seconds. Typically a timed based Dynamic analysis is for when you want to capture vibration, inertia loads, or some type of quick load/unload scenario.

Christopher


#10

Dear @cjquijano ,

this real test been done in a test laboratory for the pipe specimen and I need to make the simulation according to that time-load chart.

basically they meant to represent some fatigue behaviour with these steps as 1 cycle:

-load up
-keep the load
-reduce load
-keep the load

then again the same process.

thanks a lot


#11

Hi @tenshinshoden,
a few comments:

  • Is there any reason why you do not want to use symmetry in your model? The model that @bdelatti shared with you works and uses quarter symmetry, which reduces the runtime by at least a factor of 8 and also simplifies the simulation setup and reduces numerical difficulties. Please move on from this project: https://www.simscale.com/projects/rszoeke/pipe_bending_-_simscale_support/
  • Regarding your load history. If you use a static analysis without any strain-rate dependent material model or creep, there is no need to replicate the exact load curve from the lab test. As the load changes very slow, I do not expect any dynamic effects playing a significant role. Thus you can simplify your load curve to a simple “saw tooth” curve:

    Most importantly you do not need to calculate 1000 time steps, just use the one that are needed to capture the simplified curve + nonlinearities correctly.
  • Finally, do you have a nonlinear stress-strain curve for the pipe material - without that, there is no point in doing this load cycles at all.

Hope this helps.

Best,
Richard


#12

dear @rszoeke,

-I started it with that quarter model
-I tried to specify the load over time and getting error results.
(can you give me an example how would you do it for the above diagram /the ‘saw tooth’ curve)
It seems I am really missing here something :pensive:

I managed to upload the stress strain curve, and seem top be working for a simple 0.175t function (for the displacement Y direction as Bruno did it)

thanks,


#13

Hi @tenshinshoden,

You can control your load profile with a formula rather than a table. I find this more convenient in most cases because you can make changes on the fly without having to generate a new table each time.

For example, the following equation will produce the load profile you require.

-1 * SIN(2 * 3.14 / 100 * t) - 0.01 * t - 4

The general form is:

A \times sin(2\pi/T \times t) + m \times t + c

where:
A = amplitude [N]
T = period [s]
m = slope [N/s]
c = inital offset [N]


#14

sorry, cannot see the table properly.

thanks


#15

wow,
thanks a lot, like your solution!

how do I set up the 600sec simulation time?

thank,s

richard


#16

hi,

how would you set up that time steps and the saw tooth lines?
I am really struggling with it.

thanks


#17

dear @BenLewis ,

I cannot get it done even for a small pipe bending simulation

:persevere:


#18

To terminate the simulation after 600 sec go to Simulation Control > Timestep definition > Details and set Simulation interval to 600 seconds.


#19

Hi @tenshinshoden,

This project demonstrates how to use the load profile formula.

https://www.simscale.com/projects/BenLewis/pipe_bending/

Here is the displacement plot.

Note, I had to reverse the signs in my original formula, as the load was going in the wrong direction.


#20

thanks a lot.

Just a question,
Why did you use local force?

Thanks