Deflection reduction of the guideway of aerial PRT systems by horizontal supports

Abstract

Controlling the deflection of the aerial personal rapid transit (PRT) structure is crucial to the system’s riding comfort and energy efficiency. A nonlinear elastic analysis of a beam under combined axial and transverse loads is conducted to show a new mechanism to stiffen the PRT structure by using horizontal support. Although the classic beam theory often neglects the effect of the tensile axial force, when the deflection caused by the transverse load is large, the tensile axial force may significantly contribute to the mitigation of overall deflection, particularly for thin, long beams. Using the governing equation of beam with an axial force, the Green’s function is obtained for different boundary conditions. To demonstrate and validate the theory, three-point bending tests have been conducted for three boundary conditions: (1) two roller supports with a varying horizontal load; (2) two clamped supports with a varying horizontal load; and (3) two fixed supports with rigid constraints, which passively induce a tensile force by the transverse load. The formulation captures the nonlinear elastic behavior of the beams with horizontal constraints or axial forces, which shows that the maximum deflection of the 11 beams can reduce 38%–87% under the elastic load range. The Green’s function can be applied to arbitrary transverse loads in structural design. A smart cushion system is invented to provide horizontal support to the guideway of a lightweight, stiffened aerial PRT structure.