Searching for compressive stress of silica aerogels

[lavalite]

I have no formal training in any type of engineering, so if my request is confusing, I apologize.

I believe I am seeking data on the ultimate internal stress of various silica aerogels in compression mode.

I found a paper published by Dylan J. Boday where CVD of cyanoacrylates was used to reinforce the aerogels (1). A three-point compression analysis and rupture strength is discussed, but not internal stress. Is it possible to calculate the internal stress from the listed rupture strengths?

(1) Boday, D. et al.; chemistry of materials, 2008, 2009, 2847

 

[jrmichler]

You apparently want to find the compressive strength of various silica aerogels from the three point bending strength in that paper. Not possible, because they are measured differently and measure different properties.

The specimen in a three point bending test typically fails in tension, in which case the test measures the tensile strength in the presence of surface defects. Compressive tests are normally not sensitive to surface defects, so compressive strength can be greater than the result of a three point bending test. This is material dependent. Steel, for example, has compressive strength close to tensile strength, while concrete has tensile strength about 8% of compressive strength.

Good search terms to learn more are mechanical properties aerogel.

 

[lavalite]

Ok thanks a lot, I appreciate your reply and help.

 

[lavalite]

You apparently want to find the compressive strength of various silica aerogels from the three point bending strength in that paper. Not possible, because they are measured differently and measure different properties.

The specimen in a three point bending test typically fails in tension, in which case the test measures the tensile strength in the presence of surface defects. Compressive tests are normally not sensitive to surface defects, so compressive strength can be greater than the result of a three point bending test. This is material dependent. Steel, for example, has compressive strength close to tensile strength, while concrete has tensile strength about 8% of compressive strength.

Good search terms to learn more are mechanical properties aerogel.

I have attempted to use the search term that you suggested but I'm still having difficulty finding the information that I'm trying to find. I really wish I could find a chart that had information like type, density, and compressive strength. Does anybody know where I can find charts that have that information?

 

[Tom.G]

Your question is a bit like asking "How Strong is Wood", there are a huge variety of both! Anyhow...

Try this search (some results are behind a pay-wall):

https://scholar.google.com/scholar?...f+aerogel&hl=en&as_sdt=0&as_vis=1&oi=scholart

Cheers,
Tom

 

[lavalite]

I'll check that out, thanks for the link Tom!

 

[lavalite]

WARNING: Assumptions and approximations ahead!

The compressive strength at failure of cyanoacrylate reinforced composite silica aerogel (1) may be as high as 166,084pa at a density of 0.22g/cm^3 if;

• The sample can support 3200 times its own weight in true compression.
• The sample is cylindrical.
• The sample is twice as tall as its diameter.
• The sample is 2.3 times its unreinforced mass of 0.262g.

Sadly, if this approximation is even close to correct, then this material is 60 times weaker than I'd hoped for it to be. I guess it's back to the drawing board.

(1) Boday D.J.; et al Applied Materials & Interfaces, 2009, 1365-1366