The superconductivity technology has been receiving a great concern in engineering application. It enables to produce high magnetic field because of very high Jc density, and this high magnetic field can be utilize in various engineering field. However, as magnets become larger and larger with high current, many engineering problems have rised. Among all problems, mechanical disturbance is one of the most important problem to give strong effects on stability of superconducting magnets. Hence, the analysis of the mechanical behavior of the winding structure of superconducting magnets is of great importance, In this report, the strain behavior was measured on coils where the magnetic force by excitation was simulated by the distributed forces along the inside surface. The result is that the strain distribution showed some anomalies compared with theoretical result. The strain of the outer turn was smaller than that by theoretical analysis. It is because initial misfit (non-uniform distribution of winding of remaining stress, micro crack or spallings of binder epoxy between each windings). The misfit became larger and larger with increase of load cycle. This misfit prevented the stress transmission from inside to outside turn. It is also found that the mechanism of the degradation of coil rigidity can be a resultant of these processes.
