Mechanical characteristics of reinforced soft tubes under combined internal pressure and thermal loads

Reinforced polytetrafluoroethylene (PTFE) soft tubes are subjected to high internal pressure and thermal loads during operation. These conditions pose significant challenges to their structural reliability and the safety of aircraft piping systems. To investigate the mechanical characteristics of the reinforced soft tubes under internal pressure and thermal loads, a high-precision finite element model is developed. Firstly, the effects of braiding angle and diameter-to-thickness ratio on the load-bearing capacity of the reinforced soft tubes are examined. Subsequently, the mechanical responses under varying ambient temperatures are analyzed in conjunction with thermal loads. Finally, the accuracy of the simulation model and methodology is validated through a pressure resistance test at 21 MPa. The results indicate that 54.7°is the optimal braiding angle for the reinforced soft tubes, and a smaller diameter-to-thickness ratio enhances the pressure resistance of the tubes. The metal-reinforced layer serves as the primary structural support, with its stress increasing by 109.76% as oil pressure rises from 10.5 MPa to 21 MPa. Additionally, high temperatures induce stress concentration in the metal-reinforced layer, while extreme temperature differences result in severe deformation of the inner tube. Experimental validation demonstrates that the maximum stress error of the finite element model is within 12.22%. These findings provide crucial insights into the design and optimization of the reinforced soft tubes, emphasizing how material properties and structural configurations can improve the safety and reliability of aircraft piping systems under complex flight conditions.