Challenger O Ring Material

The joint failed because at cold temperatures the silicone o ring material lost its resilience and took a set.

Challenger o ring material.

Feynman now believed that he had the solution but to test it he dropped a piece of the o ring material squeezed with a c clamp to simulate the actual conditions of the shuttle into a glass of ice water. The temperature at the time of the challenger liftoff was 32 degrees f. The disaster of challenger mission sts 51 l was the result of human engineering. Feynman s famous c clamp experiment.

November 1981 o ring erosion discovered after second shuttle flight. Number of o ring incidents vs. Joint temperature incidents when o rings failed source. Report of the presidential commission on the space shuttle challenger accident 6 june 1986 volume 1 page 145 link color added.

Then when the the booster was lit and is casing expanded the o rings retained their cold compressed shapes and allowed hot gas from inside the casing to spurt out the resulting gap in the seal. The material of the failed o ring was fkm which was specified by the shuttle motor contractor morton thiokol. January 24 1985 shuttle flight that exhibited the worst o ring blowby. Fkm is the short form for the fluoroelastomer category according to the american standard astm.

In the parker o ring handbook ord 5700 paragraph 4 0 says it has been said that o rings are the finest static seals ever developed perhaps the prime reason for this is because they are almost human proof. July 1985 thiokol orders new steel billets for new field joint design.