# Flexural Strength of Aluminum 6061?

1. Sep 14, 2010

### mcouch

Hi all,

I've got a pressure vessel that is just an aluminum cylinder with flat caps welded to the ends. Currently, I doing some FEA to properly size those flat caps for a certain factor of safety. Since the pressure in the tank will cause a uniformly distributed load on the wetted surface of the cap, I understand I'm dealing with bending stresses. My plan was to calculate the Von Mises Stress and compare it to the bending strength (or flexural strength), but I can't seem to find that strength property for aluminum 6061 anywhere!

Is there a reason this isn't a well documented material property? Or, if I've gone down a wrong path here, can someone help guide me back onto the right one?

Any help is appreciated!

2. Sep 14, 2010

### nvn

mcouch: Because your aluminum 6061 material is isotropic and linearly-elastic, the flexural yield strength is the tensile yield strength.

3. Sep 14, 2010

### Khowe9

There are a few different types of 6061, Annealed or Tempered/Heat Treated (T4 and T6).

Yield Stength is:
6061-O temper is 55 MPa (8 ksi)
6061 T6 is about 275-276 MPa (40 ksi)

Source: Fundamentals of Materials Science and Engineering by William Callister , Jr.

4. Sep 14, 2010

### Q_Goest

Pressure vessels should comply with the codes applicable in your country. For example, in the US this might fall under either a piping code or the boiler and pressure vessel code, depending on size and pressure rating. Those codes have an allowable stress listed depending on the temperature the vessel is exposed to.

5. Sep 23, 2010

### CaptainofIron

This is a good post

I would check into ASME BPVC Section II Part D, OR go to Battelle MMPDS-04

In some cases the materials are not very well characterized, or testing hasnt been done, in these cases you will not find any specifications

I recently had to calculate an allowable stress (I used ASME B31.3 basic rules) for 15-5 Stainless Steel because no Code I could find had one