Need stress value of aluminium for project work

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Discussion Overview

The discussion revolves around the stress value of aluminium, specifically Aluminium 6061t, in the context of a project involving a sealed cylindrical vessel intended to operate underwater at a depth of 10 meters. Participants explore the implications of pressure on the material's deformation and structural integrity.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant requests the stress value of aluminium and cites specific dimensions and yield strength for their project.
  • Another participant questions the nature of the project and the need for citation, seeking clarification on the context.
  • A different participant asserts that some deformation is expected under load, particularly if there is a pressure differential between the inside and outside of the vessel.
  • Reference is made to "Roark’s Formulas for Stress and Strain" for formulas applicable to cylindrical pressure vessels under external pressure, with a mention of a Finite Element Analysis yielding a maximum von Mises stress of about 40 MPa.
  • One participant queries whether the aluminium vessel could withstand pressures at a depth of 4000 meters based on the previously mentioned stress analysis.
  • Another participant calculates the maximum depth the vessel could theoretically withstand without a safety factor, based on the yield strength of the material and the stress determined from the analysis.

Areas of Agreement / Disagreement

Participants express differing views on the deformation of aluminium under pressure, with some asserting that deformation will occur while others provide calculations suggesting potential depth limits for the vessel. The discussion does not reach a consensus on the stress values or the implications for the vessel's design.

Contextual Notes

The discussion includes assumptions about the pressure conditions and material properties, as well as references to specific analytical methods without resolving the mathematical steps involved. The implications of safety factors are also not fully addressed.

Hakuyu
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TL;DR
Im not a physics student but I really need to prove that aluminium will not deform 10m underwater
Summary: I am not a physics student but I really need to prove that aluminium will not deform 10m underwater

Hi I am doing a project of a product which will sink underwater.
It will be a sealed cylindrical vessel, length 2m, width 1m, thickness 0.02m.
Aluminium 6061t will be used with a yield strength of 276MPa.
Pressure of water 10m underwater will be 99kPa.

If you can provide me with the stress value of aluminium please also provide me with your designation as I need to cite it with your approval.

Thank you so much !
 
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Hakuyu said:
Summary: I am not a physics student but I really need to prove that aluminium will not deform 10m underwater

Summary: I am not a physics student but I really need to prove that aluminium will not deform 10m underwater

Hi I am doing a project of a product which will sink underwater.
It will be a sealed cylindrical vessel, length 2m, width 1m, thickness 0.02m.
Aluminium 6061t will be used with a yield strength of 276MPa.
Pressure of water 10m underwater will be 99kPa.

If you can provide me with the stress value of aluminium please also provide me with your designation as I need to cite it with your approval.

Thank you so much !
Is this for a school project? If so, which class?

If not, what is the overall project that you are working on? And what do you mean by "cite it with your approval"? Approval for whom?
 
Sorry to disappoint you, but there will be some deformation assuming that the pressure inside is different from that outside. Everything has some deformation under load.
 
In „Roark’s Formulas for Stress and Strain” book you can find formulas for stress in cylindrical pressure vessels subjected to external pressure. But I performed Finite Element Analysis assuming flat bottom and maximum von Mises stress result is about 40 MPa.
 
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1570796574071.png


Using the above graph can I assume his aluminium vessel is good to about 4000m depth?

FEAnalyst said:
In „Roark’s Formulas for Stress and Strain” book you can find formulas for stress in cylindrical pressure vessels subjected to external pressure. But I performed Finite Element Analysis assuming flat bottom and maximum von Mises stress result is about 40 MPa.
 
Spinnor said:
Using the above graph can I assume his aluminium vessel is good to about 4000m depth?

Based upon the the flat end closure plate's above determined 40 MPa stress at the 10 m depth and the stated maximum allowed S yield of 276 MPa for the material, the maximum depth = 10 x 276/40 = 69 m without any safety factor.
 
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