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Old 02-13-2016, 02:03 PM
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Mucci Mucci is offline
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Tubing strength & weight comparison chart?

I'm curious, is there a chart that compares things like tubing material, size, strength and weight?

i.e. if I wanted to replace a steel tube subframe with aluminum I could use this chart to figure out what diam/wall tube I would need to be comparable in strength and if there would be any weight savings in doing so.

Thanks for any help. I'm an Industrial Designer attempting to teach myself structural engineering on the internet
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Old 02-13-2016, 03:18 PM
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entropy entropy is offline
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I've never seen such a table but I sure would like to!!

I know that on the boats there was zero advantage in weight for comparable strength Roll cages, the DOM/CrMo cages weighed far less the the Aluminum.

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Old 02-15-2016, 08:51 AM
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Graham08 Graham08 is offline
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It's not really a simple analysis to do, because there are a number of other factors in play besides material strength. For example, the construction method to get the most out of one material may be completely different than another, so the parts would look completely different. The best example offhand is that with steel, the loss in strength due to welding is a much less significant factor than it is with the higher strength aluminum alloys (if welding is even possible). So, with steel, a tubular structure with welded joints may be the way to go, where with aluminum, to get the best strength/weight, you might fabricate a structure from sheet metal with riveted joints.

Another thing to keep in mind is stiffness, if it's important for the application. For most metals, the stiffness relative to steel is proportional to the weight relative to steel. So, for aluminum, it's approximately 1/3 the weight of steel for the same volume, but also about 1/3 the stiffness in the same geometry. Titanium is about half (really 56%) the weight of steel, but also half the stiffness. So, again, an exact duplicate of the steel structure in a lighter material isn't going to perform the same way, which may or may not be important to your application.

As with all good engineering questions, the answer is "it depends".

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Old 02-15-2016, 02:03 PM
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Mucci Mucci is offline
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Quote:
Originally Posted by Graham08 View Post

As with all good engineering questions, the answer is "it depends".

I figured as much! Thanks for laying that out
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Old 02-15-2016, 10:01 PM
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deaner deaner is offline
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Quote:
Originally Posted by Graham08 View Post
It's not really a simple analysis to do, because there are a number of other factors in play besides material strength. For example, the construction method to get the most out of one material may be completely different than another, so the parts would look completely different. The best example offhand is that with steel, the loss in strength due to welding is a much less significant factor than it is with the higher strength aluminum alloys (if welding is even possible). So, with steel, a tubular structure with welded joints may be the way to go, where with aluminum, to get the best strength/weight, you might fabricate a structure from sheet metal with riveted joints.

Another thing to keep in mind is stiffness, if it's important for the application. For most metals, the stiffness relative to steel is proportional to the weight relative to steel. So, for aluminum, it's approximately 1/3 the weight of steel for the same volume, but also about 1/3 the stiffness in the same geometry. Titanium is about half (really 56%) the weight of steel, but also half the stiffness. So, again, an exact duplicate of the steel structure in a lighter material isn't going to perform the same way, which may or may not be important to your application.

As with all good engineering questions, the answer is "it depends".

Excellent answer, thanks for your contribution.
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