Fundamental mechanisms of winding motions during charging superconducting test coils are discussed under coil simulation conditions. The winding motion is detected by AE techniques and plane strains of the thin layer test coils. The plane strains can be divided into the tensile strain which is along a circumferential direction of the coil and the compressive strain which is in the axial direction of it.
Mechanical dissipation energy densities in both the directions are estimated and compared with AE energy. It is found that the compressive strain is an influential source on the AE signal and the coil instability.