Jack,

Not to harp but the biggest problem for E/G in terms of making a vacuum chamber is the fact that E/G's normal failure mode is brittle failure through crack propagation. While it is true that metals can also fail by cracking, they usually fail in a ductile mode when fatigue is not an issue according to my understanding. Also, the exact position of mesh reinforcement in the part will have enormous consequences.

Keep in mind that the flexural strength of E/G is only about 3ksi whereas aluminum is at least 30 depending on the alloy and heat treatment. Also keep in mind that because the material is created by a random process that it doesn't necessarily have perfectly known or consistent material properties. B.W. Staynes in his 1975 paper suggested that an overall safety factor of at least 2 be used for load carrying designs and given the brittle nature of the material my handbooks suggest that 4 is probably the appropriate safety factor.


Nothing is impossible but I'd want to do some pretty rigorous engineering before being within the event horizon of an E/G vacuum chamber.

Sorry I haven't had a chance to do more calculations on fracture properties and thanks to new poster dilbert for the estimate of voids.

Regards all,

Cameron