CORC® cables or wires are composed of helical wound HTS REBCO tapes in multiple layers with high flexibility. However, compared with traditional multi-filament cables, the helical tape structure also brings new challenges to predicting the CORC® will be subjected to radial extrusion and circumferential stretching due to the electromagnetic force's action during operation. In this study, starting with the cabling process, the deformation of the tape, the normal contact force and friction distribution between the tape and the core are described. The effect of different winding parameters, such as core radius and winding helix angle, are obtained by combining theory and Finite Element Method (FEM) simulation. Then axial tensile loading of the multilayer CORC® is simulated and compared with the experimental curve including its critical current degradation. The results describe the interaction between tape and core that occurs during the tensile loading. The tape and the core are extruded and friction is generated, directly causing critical current degradation. The developed analytical and FE models can predict the mechanical and electrical properties of CORC® cables.