Spatial Rigid-Flexible-Liquid Coupling Dynamics of Towed System Analyzed by a Hamiltonian Finite Element Method

Huaiping Ding,Xiaochun Yin,Qiao Wang,Wei Hu

doi:10.3390/jmse9111157

Abstract

An effective Hamiltonian finite element method is presented in this paper to investigate the three-dimensional dynamic responses of a towed cable-payload system with large deformation. The dynamics of a flexible towed system moving in a medium is a classical and complex rigid-flexible-liquid coupling problem. The dynamic governing equation is derived from the Hamiltonian system and built-in canonical form. A Symplectic algorithm is built to analyze the canonical equations numerically. Logarithmic strain is applied to estimate the large deformation effect and the system stiffness matrix will be updated for each calculation time step. A direct integral solution of the medium drag effect is derived in which the traditional coordinate transformation is avoided. A conical pendulum system and a 180° U-turn towed cable system are conducted and the results are compared with those retraced from the existing Hamiltonian method based on small deformation theory and the dynamic software of Livermore software technology corp. (LS-DYNA). Furthermore, a circularly towed system is analyzed and compared with experimental data. The comparisons show that the presented method is more accurate than the existing Hamiltonian method when large deformation occurred in the towed cable due to the application of logarithmic strain. Furthermore, it is more effective than LS-DYNA to treat the rigid-flexible-liquid coupling problems in the costs of CPU time.

Highlights

There are many applications in which payloads are towed by three-dimensional airborne platforms: towed remotely operated vehicles (ROVs) [1], flexible aerial refueling hose system [2], aircraft-towed cables [3], and tethered satellite systems [4]
The dynamics of cable-payload systems have been of major interest for several decades due to their nonlinear features caused by the flexible cable and airflow drag, the prediction of the nonlinear dynamic responses of cable-payload systems has become to be an active field of investigations
This paper aims at the three-dimensional rigid-flexible-liquid coupling dynamic problems of the towed cable-payload systems, a numerical model based on Hamiltonian theory is proposed and solved by finite element method, in which the large strain influence, the damping effect, and the aerodynamic effect are taken into consideration

Summary

Introduction

There are many applications in which payloads are towed by three-dimensional airborne platforms: towed remotely operated vehicles (ROVs) [1], flexible aerial refueling hose system [2], aircraft-towed cables [3], and tethered satellite systems [4]. The dynamics of cable-payload systems have been of major interest for several decades due to their nonlinear features caused by the flexible cable and airflow drag, the prediction of the nonlinear dynamic responses of cable-payload systems has become to be an active field of investigations. The towed systems moved in the fluid medium will be subject to fluid resistance such as airflow drag force and water resistance, coupling with the rigid payload and flexible cables, it will become to be classical and complex rigid-flexible-liquid coupling problems. Researchers proposed many numerical methods to analyze the towing process dynamics, mainly including lumped mass method, finite difference method, and finite element method

Objectives

Methods

Findings

Conclusion