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Re: Steel vs. Aluminum

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Posted By<" ">david schenken on March 14, 2002 at 00:13:04:

In Reply to: Steel vs. Aluminum posted byPat Ryan on March 06, 2002 at 16:08:12:

: I am a prototype technician for an international designer and manufacturer of portable tradeshow displays. ...

The ratio of tensile strength to weight of high grade aluminum is about the same as for good grade steel. For tensile applications it is therefore a wash.

For bending applications, aluminum can win. For a plate in bending the strength of the plate is related to the cube of the thickness. Aluminum being about 1/3 the density of steel can be at a 9 times advantage based on thickness, which offsets the 1/3 third in strength. So a tube could have a more dent resistant wall in aluminum than steel for the same weight.

For compression applications there is a similar, though not as pronounced, trend to improvement.

The one thing steel does have over aluminum is that there is a load below which steels have an indefinite fatigue life. It is pretty low. Foe aluminum that number is pretty close to zero. Any repeated load, after enough (billions??) of cycles will fatigue aluminum. Steel could persevere.

I think if you look to bicycle manufacture (truss, loaded!!) you'll see that steel is the cost winner, with aluminum, titanium, carbon fiber being at various price points in the higher performance.

Perhaps composites would be your edge - providing attach points were hardened for mounting screws.

Follow Ups

Re: Re: Steel vs. Aluminum Neil Moran 04:45:42 3/15/2002 (1)
- Re: Re: Re: Steel vs. Aluminum Dave Schenken 23:49:13 4/04/2002 (0)

Subject: Re: Re: Steel vs. Aluminum

Comments:: : I am a prototype technician for an international designer and manufacturer of portable tradeshow displays. ... : The ratio of tensile strength to weight of high grade aluminum is about the same as for good grade steel. For tensile applications it is therefore a wash. : For bending applications, aluminum can win. For a plate in bending the strength of the plate is related to the cube of the thickness. Aluminum being about 1/3 the density of steel can be at a 9 times advantage based on thickness, which offsets the 1/3 third in strength. So a tube could have a more dent resistant wall in aluminum than steel for the same weight. : For compression applications there is a similar, though not as pronounced, trend to improvement. : The one thing steel does have over aluminum is that there is a load below which steels have an indefinite fatigue life. It is pretty low. Foe aluminum that number is pretty close to zero. Any repeated load, after enough (billions??) of cycles will fatigue aluminum. Steel could persevere. : I think if you look to bicycle manufacture (truss, loaded!!) you'll see that steel is the cost winner, with aluminum, titanium, carbon fiber being at various price points in the higher performance. : Perhaps composites would be your edge - providing attach points were hardened for mounting screws.

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