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[TowerTalk] Steel vs Aluminum

To: <>
Subject: [TowerTalk] Steel vs Aluminum
From: (John D. Farr)
Date: Fri, 30 Mar 2001 22:18:23 -0600

Thanks for the response. I was hoping for a reference to an actual standard
such as the Building Code Requirements for Structural Concrete by the ACI or
Manual of Steel Construction by the AISC. The page in Marks that addresses
the subject is quite enough to understand fatigue, but it does not contain
near enough information to actually do a design in aluminum.

In recent years, have taken all of the undergraduate civil engineering
courses from the local university that pertain to structures. Aluminum has
not been mentioned once since I took a sophomore course in basic mechanics
of materials many years ago. This course was strictly theoretical. I'm now
looking for a book that contains design procedures and constraints in
aluminum design. The ACI and the AISC provide this for concrete and steel.
Isn't there a standard somewhere for aluminum design? Seems like it would be

thanks again
-----Original Message-----
[]On Behalf Of
Sent: Friday, March 30, 2001 9:39 AM
Subject: RE: [TowerTalk] Steel vs Aluminum

     This information can be found in any book on "Engineering of
Materials".  Another source of good engineering information is the
"Marks Standard Handbood for Mechanical Engineers."
     All the talk here about failure on beam can be explained but,
it would take several semesters of Statics, Dynamics, Strength of
Materials, and Vibration Analysis.
     If you live close to any College you can get a good deal
on used text books at the end of semesters.  Also, a library will have
a used book sale and sometimes that include technical books for


Joseph D. Mowery
Firefighter / EMT
Heavy Tactical Rescue

|        |          "John D.     |
|        |          Farr"        |
|        |          <johnfarr@ro.|
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|        |          03/29/01     |
|        |          07:41 PM     |
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  |       To:,
  |       cc:     (bcc: Joseph Mowery/N13/N10/NDept/NSWCDD)
  |       Subject:     RE: [TowerTalk] Steel vs Aluminum


Joe: This looks like you have found some sort of specification on designing
with aluminum. Could you tell me which ones this info is found in?
thanks, John KC4ZXX

-----Original Message-----
[]On Behalf Of
Sent: Thursday, March 29, 2001 1:34 PM
Subject: Re: [TowerTalk] Steel vs Aluminum

     The property that you are trying to describe in Aluminum is
fatigue.  Fatigue failures typically occur in three stages.  First, a tiny
crack initiates at the surface, often at a time well after loading begins.
Next, the crack gradually propagates as the load continues to cycle.
Finally, sudden fracture of the material occurs when the remaining
cross-section of the material is too small to support the applied load.
     There are three design criteria when dealing with Aluminum
and fatigue.

Endurance limit, which is the stress below which there is a 50%
probability that failure by fatigue will never occur.

Fatigue life which tells up how long a component survives at a
particular stress.

Fatigue Strengh is the maximun stress for which fatigue will not occur
within a particular number of cycles.

Endurance ratio is equal to endurance limit divided by tensile strength
and is approximately 0.5

Good DX,

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