The Investigation of the Mechanical Behavior of a Braided Parachute Suspension Line using a Mesomechanical Finite Element Model

Parachute suspension lines shed vortices during descent, and these vortices develop oscillating aerodynamic forces that can induce forced parasitic vibrations of the lines that have an adverse impact on the parachute system. Understanding the line’s mechanical behavior can assist in comprehending the vibrations that are experienced by the suspension lines. A well calibrated structural model of the suspension line could be used to help identify how the braid’s architecture contributes to its mechanical behavior and to explore if and how a suspension line can be designed to mitigate these parasitic vibrations. In the current study, a mesomechanical finite element model of a polyester braided parachute suspension line was constructed. The line geometry was built in the Virtual Textile Morphology Suite (VTMS), and a user material model (UMAT) was implemented in LS-DYNA® release 14 to describe the material behavior of the individual tows. The results of the experimental tension tests that were performed on the individual tows of the braid served as a starting point to calibrate the material properties to achieve good correlation between the mesomechanical model and the experimental tension tests of the physical suspension line. The calibrated model of the braided cord was then twisted in torsion, and the model was found to show good correlation with dynamic and static experimental torsion test data. The availability of virtual models of suspension lines can ultimately assist in the design of suspension lines that mitigate flow-induced vibration.