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Hollow steel pipe is stronger or solid steel rod?

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Question ajoutée par Alex Al Yazouri , General Manager , Al Mushref Cooperative Society
Date de publication: 2015/01/12
Utilisateur supprimé
par Utilisateur supprimé

Hollow steal pipes mor strength than others

Vinod Jetley
par Vinod Jetley , Assistant General Manager , State Bank of India

For a given material, and given outer dimensions, the maximum strength is achieved if the rod is solid (not hollow), but this also takes a lot of weight.

 

For a given material, and given weight, the maximum strength is achieved by a hollow cylinder, that is of larger diameter than the solid rod of that weight.

 

Most of the strength of a cylinder comes from the outer portions. I think the contribution goes like the cube of the radial position. So, if you took a solid rod and drilled out a half the volume from the center, you do not lose half the strength. You only lose about10% of the strength, but you've saved on half the weight.

 

So, strength to weight ratio is better for a hollow pipe than a solid rod.

LABIB KOOLI
par LABIB KOOLI , Director of the Sectoral Center for Training in Hotel Technologies at Southern Hammamet , Tunisian Vocational Training Agency (ATFP)

I guess a solid steel rod is stronger than a hollow steel pipe 

Cause the second moment  of a rod area is superior than that of a pipe 

Solid Circular Cross Section

area moment of inertia circular section

Ix = π r4 /4

    = π d4 /64         (4)

where

r = radius

d = diameter

 

Iy = π r4 /4

    = π d4 /64         (4b)

Hollow Cylindrical Cross Section

area moment of inertia cylindrical section

Ix = π (do4 - di4) /64         (5)

where

do = cylinder outside diameter

di = cylinder inside diameter

 

Iy = π (do4 - di4) /64   

Alex Al Yazouri
par Alex Al Yazouri , General Manager , Al Mushref Cooperative Society

On a per pound basis, steel pipe is stronger in bending and is less likely to buckle in axial compression.

muhammad atif  Siddiq
par muhammad atif Siddiq , Supervisor , CHANI GHOT

Hollow steel pipe

جعفر هندي زين السقاف
par جعفر هندي زين السقاف , "Certified trainer by the Yemeni Engineers Syndicate." , Engineers Syndicate

Agreed with the answer given by Mr. Alex Al Yazouri.

Elke Woofter
par Elke Woofter , Project Assistant , American Technical Associates

 

4down vote

http://www.physicsforums.com/archive/index.php/t-37701.html says

"Most of the strength of a cylinder comes from the outer portions. I think the contribution goes like the cube of the radial position. So, if you took a solid rod and drilled out a half the volume from the center, you do not lose half the strength. Strength to weight ratio is better for a hollow pipe than a solid rod."

The definition for the second moment of inertia Ic for a filled and hollow cylinder can be found onhttp://en.wikipedia.org/wiki/Second_moment_of_area:

Ic=Ay2dxdy=R02π0r2dϕ rdr=πr44

 

The surface area of the filled cylinder is:

A=πr2

 

Compare filled and hollow cylinder of equal mass:

sc=IcA=r24 , cylinder with fractional internal radius ri=xro and x<1: sh=IhA=r4(1x4)4r2(1x2)=r2(1x2)(1+x2)4(1x2)=r2(1+x2)4>sc .

 

This means a hollow cylinder is stronger than a rod of equal mass and the same material. A hollow cylinder with a bigger inside diameter is better. In the limit x1 the hollow cylinder is twice as strong. Note that this limit isn't physically viable as it would be an cylinder with infinite radius and infinitesimally thin wall. However it is useful to define the upper limit of the second moment of inertia. I didn't expect the increase in strength only a factor of two.

 

Kaamila Tahseen
par Kaamila Tahseen , Change Management Team Manager , cognizant technology solutions

Sorry I dnt knw this one, bt i jus googled and many say Hollow steel...

Wolf Klaas Kinsbergen
par Wolf Klaas Kinsbergen , Managing Director, Designer , ingenieursbureau KB International NV

Depends on steel quality, diameter, and thickness of the pipe and solis pipe. With these three you can determine the mechanical values (A, W, I) and see what is stronger and why.

Tarique dahri
par Tarique dahri , Assistant Engineer , nawabshah medical university

Hollow steel pipe is stronger if the length and weight are the same because it is harder to strain a denser object that less dense. 

solid rod is stronger than hollow rod in all of load cases

but we are Engineers , we use stronger and economic so if load is axial load we use solid rod as it more stronger than hollow rod but if shear load we use hollow in safe side as it more economic   

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