Square ligaments in perforated rolled plate

[MVI]

Dear all,

For a school research I am improving a certain silencer. This silencer is made according to ASME B31.1 in combination with ASME BPVC Section VIII. Basically the product is made of several layers of perforated pipe/plate of which the first pipes are drilled with a certain pattern. For this pattern Efficiency of BPVC Section VIII UG-53 is used.

For the last layer, a perforated and rolled plate is used but I would like to use square holes in this plate. I do have results of a FEM analysis, which shows that the plate with square holes is stronger than a comparable plate with round holes. But I would like to calculate the effiency of the square holes in some way. I have not found information about this problem in Section VIII, does anyone have experience with this?

 

[SnTMan]

Might try this site.

BTW, I'm a little skeptical about the square vs round holes thing, but then I'm no FEA person

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[EdStainless]

The square holes will need a generous corner radius or mechanical and thermal fatigue could be serious issues.
You don't often see square holes because the fraction of open area is less than with round holes.
You do see slots sometimes, it allows the ligaments to be oriented for the 'strong' direction.

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P.E. Metallurgy, Plymouth Tube

 

[MVI]

Thanks for the thoughts and link.

@SnTMan, what is the reason for your skepticism?

@EdStainless, the holes have a size of 15 mm square and a corner radius of 3 mm. It is not tested on fatigue, but for such a corner radius this should not be a big issue right? According to the FEA analysis a square hole pattern with a few % more open area should be stronger than the round hole pattern. Slots I have been thinking over, but these will have impact on the noise reduction of the product so I cannot use this.

 

[SnTMan]

MVI, don't know your definition of "stronger" but it just doesn't seem right. I don't really have a reason

The problem with sloppy work is that the supply FAR EXCEEDS the demand