The analysis was carried out in two steps. The first was to pre-load the tool and indent the pipe, the indent varied depending on the pre-load. The Pocket component was fully fixed on the outside diameter with the pipe component being pulled to cause the ball to roll and create an indent on the pipe. This step was carried out for eight different indentation depths.
After pre-loading and achieving the required indentation, the torque was applied to the tool. This was applied as a rotation of 1.2 degrees.
The graph right shows the Torque vs. Rotation behaviour for different indentation depths. A logarithmic behaviour was observed, the higher the indentation the higher the maximum torque that could be applied.
The graph below right shows Max Torque vs. Initial Indentation. A best-fit curve was fitted to the eight points had been calculated and a 3rd order polynomial below was found to give very good correlation to the calculated points:
It was also found that the pulling force needed to produce the initial indentation, did not exhibit linear behaviour and it too followed a 3rd order polynomial curve. With indentations greater than 1.2mm pulling forces tend to keep constant.