ASME Section VIII Div.2 | Strain range vs no. of cycles

[shiraz883]

Hi,

I am trying to find out the no. of cycles an equipment can withstand with respect to the strain range (in %).

So I have simulated (in ANSYS) full load (temp.) and then unload (ambient) for 5 loops i.e 5 loading and 5 unloading which makes 10 steps.

Now I want to see the plot of strain range vs time so that I can calculate the conservative strain range for the cycle of load and compare it with the graph of strain range vs no of cyles to determine the equipment's ability to withstand the number of cycles.

My question is : this strain range is the equivalent plastic strain or von-mises plastic strain (Ansys has options of plotting eqv. plastic strain and also von-mises plastic strain)?



Shiraz
Sr. Engineer

 

[MrPDes]

"Equivalent" is the same as "Von Mises" and "Intensity" is the same as "Tresca".

The options I have are equivalent elastic strain, equivalent plastic strain and equivalent Total strain (and equivalent thermal and creep strain).

I'm guessing the two options you are referring to are equivalent plastic strain and equivalent Total strain.

Equivalent Total strain = equivalent Plastic strain + equivalent Elastic strain (plus equivalent thermal and creep strain if they are present)

Plot them and sum the maximum strains in each plot to see for yourself.

 

[shiraz883]

Hi,

If you go to post processing -->Plot results-->Contour Plot--> Nodal Solution (powergraphics off)--> plastic strain

Under plastic strain you have two options which are Von-Mises plastic strain and Equivalent plastic strain.



Shiraz
Sr. Engineer

 

[shiraz883]

btw I am using Ansys 18.2

Shiraz
Sr. Engineer

 

[TGS4]

Follow the rules as written in 5.5.4. You will be performing the vaccinations on the component strain ranges, not on the equivalent strain range.