fig1

Figure 1. The mechanical analysis of the bar in “wine-rack” structures for the two conditions of the angle between the bar and principal axis (i-axis). (A) The condition for the angle smaller than 45°, in which the hydrostatic pressure results in a torque to drive the bar rotate toward the i-axis; (B) The condition for an angle larger than 45°, in which the hydrostatic pressure results in a torque to drive the bar rotate to be away from the i-axis. The rotation direction of the bar is highlighted by yellow arrows.