In November 2024, news of an existing air leak on a Russian transfer tunnel on the International Space Station made the headlines. While the exact cause of this leak hasn’t been determined, many potential factors, including residual stress, have been mentioned.
Jeff Foust reported for SpaceNews about this structural issue on the orbiting laboratory, noting that the two countries disagree on the exact cause. Quoting Bob Cabana, former NASA astronaut and chair of the agency’s ISS Advisory Committee, Foust wrote:
“[Cabana] said Russian engineers believe the cracks are likely caused by ‘high cyclic fatigue’ from micro-vibrations. NASA, by contrast, believes several factors are at play, including pressure and mechanical stress, residual stress, material properties of the module and environmental exposure.”
A September report by NASA’s Office of Inspector General (OIG) stated that “both agencies have narrowed their focus to internal and external welds” as a cause of the leaks.
While we can’t say for certain what the cause of the module leak is, we can provide our readers with some insight into some of the topics presented in this story:
Weld joints are usually critical design locations and in a previous post, we discussed what happens to material when it is welded and the effects of the residual stress that develops in the region because of this process.
Fatigue is a failure mechanism that is activated by cyclic loading and unloading of a structure, which can be accelerated by the presence of tensile residual stress.
As more information is released about this issue on the ISS, we’ll return with an update.