How to do the Fatigue Analysis of Diesel Engine Piston???

Altair Forum User

Want to do fatigue analysis of diesel engine piston as the part of master's thesis.

 

 

Initially I have tried out a 2D fatigue analysis problem of a mild steel strip and got the results.

 

Then tried to do the fatigue analysis of piston using the same material and same method.

I got good VMS and displacement values for the static sub-case and the pictures are attached.

 

 

 

 

But for the fatigue sub-case didnt give the necessary results.

 

 

and

 

I have followed the same method of 2D problem,PSOLID element is used for the analysis of piston.

(higher order tetrahedron element-10noded element)

Hope the wrong result is caused due to the lack of adjustments in converting a

2D problem to a 3D problem,like the changes needed for defining CARDS etc.

 

Varying pressure with respect to crank angle,for 100 cycles is applied for this fatigue analysis of Piston.

Please Help...

 

Ayyappadas

 

Altair Forum User

Someone plz reply... 

Altair Forum User

Hi,

 

it is a complex subject and not easy to give a answer.

 

As i can see, you got damage at the right location (where the high stresses are located).

Normaly damage has to be smaller then 1 for fatique strength. The values on your legend are very high.

 

I can't see the problem, but i guess it is a problem of input parameters (especially for fatique).

 

Sry, Regards

Mario

Altair Forum User

Sir,

 

I have further modified the problem and obtained results as shown below.

Analysis is done for a  Single Cycle of pressure variation and values of life obtained are very low...

<?xml version="1.0" encoding="UTF-8"?>

 

damage

<?xml version="1.0" encoding="UTF-8"?>

 

Fatigue parameter CARD used also shown

<?xml version="1.0" encoding="UTF-8"?>

 

I have uploaded the complete analysis to Google Drive,and am happy to share the problem

by giving you the IDs...

 

ayyappadas73@gmail.com

This is my mail ID, I can send the ID and password of Google drive to your mail.

 

Please Help...

 

tinh

Altair Forum User said:

Hi,

 

it is a complex subject and not easy to give a answer.

 

As i can see, you got damage at the right location (where the high stresses are located).

Normaly damage has to be smaller then 1 for fatique strength. The values on your legend are very high.

 

I can't see the problem, but i guess it is a problem of input parameters (especially for fatique).

 

Sry, Regards

Mario

 

Hi Mario

Could you plz explain what 'damage (s)' means? what is it calculated from? what is '(s)'?    I cannot find in help