You use expansion joints like these: https://en.wikipedia.org/wiki/File:Flanged_Rubber_Bellows.jpg https://en.wikipedia.org/wiki/File:Flanged_Rubber_Bellows.jp.

You use expansion joints like these: https://en.wikipedia.org/wiki/File:Flanged_Rubber_Bellows.jpg https://en.wikipedia.org/wiki/File:Flanged_Rubber_Bellows.jp... They're made of rubber, fiberglass and other flexible but strong materials. I don't know how well they'd handle the vacuum stresses but I don't think it'd be too extreme.