The dimensional reduction or shortening of the face-to-face parallel length of the joint measured along the longitudinal axis.
The dimensional increase or lengthening of the face-to-face parallel length of the joint measured along the longitudinal axis.
Lateral deflection is movement perpendicular to the axial plane of the expansion joint. It is a shear motion on the bellows.
The movement of the joint due to vibrations which are effectively intercepted and insulated against transmission to the remainder of the system.
The displacement of the longitudinal axis of the joint from its initial straight line position (a combination of axial elongation and axial compression).
The twisting of one end of the expansion joint with respect to the other end about its longitudinal axis.