Perforated Metal Sheet - Solid sheet approach 1

[simaonobrega]

Hello everyone,

Framework

I am currently working, for the first time, with perforated metal sheets. I am using them to create tubes and also curved panels.
To analyse my structure, I tried using FEM but I didn't succeed since my NX wasn't able to support the huge amount of holes (I have panels with approximately 3m x 1.5m). After searching for alternative ways to evaluate this case, I came across the possibility of replacing the perforated metal sheet by an equivalent solid panel with corrected values for the Modulus of Elasticity, E, and Poisson’s ratio, v (approach detailed at

http://www.iperf.org/perforating/knowledge-center/perf-handbook/strength-perforated-metals/)

My questions are then:

[ol 1]
[li]Assuming a solid body means that I am neglecting the stress concentration around the perforated holes. How do you normally account for this effect?[/li]
[li]I have seen corrections for the Young's modulus, yield strength and Poisson's ratio. Nevertheless, I have never seen corrections for bulk and shear modulus. Do you normally assume the same values for the latter two?[/li]
[li]Is there any reliable bibliography for the material properties detailed in point 2, as a function of material and hole pattern?[/li]
[/ol]

Thank you in advance!

 

[structure567]

I think you should cross post this onto the mechanical engineering general discussion forum.

 

[dhengr]

Simaonobrega:
I would want to talk with the engineering dept., one of their good/smart engineers, not the sales dept., with a company which produces this type of plate, to be sure how to apply the design info. their handbook provides. I would also ask them for a list of ref. mat’ls., textbooks, test reports, etc. etc., for my own further reading and edification. I suspect the graphed ratios, etc. have been developed by much testing of typical products. The stress concentration situation around the holes has been accounted for in the testing, so you shouldn’t have to account for this a second time. But, I would not stretch this thinking to a real fatigue situation, that would take some further thought, study and research. Corrections for bulk and shear modulus are probably not particularly important in the way this info. is intended to be used. But, some adjustment factors for bending stress/action (Fy*/Fy) in both short span (strongest spanning direction) and long span (weaker direction) directions, and modulus of elasticity adjustment factor (E*/E) and Poisson's Ratio (ν*) are needed for this approx. solution. Note also, that this whole approach assumes/contemplates that “effective elastic constants presented herein are for plane stress conditions and apply to the in-plane loading of the thin perforated sheets of interest,” and this may be thin pl. bending, stretching or biaxial action, thus the need for ν*. I would then use my normal textbooks and methods for first order analysis of thin plates to check bending and combined stresses and deflection, and some biaxial conditions, and then factor my results the by the graphic factors.

 

[simaonobrega]

Hello Dhengr,

Thank you for your feedback.
I agree with your detailed approach and I will contact the supplier to be able to clarify the points that you have accurately mentioned!

P.s. thanks structure567 for the advice.