# NONLINEAR DYNAMIC STUDY OF A SIMPLIFIED SOLAR SAIL STRUCTURE

## Palavras-chave:

Nonlinear Dynamic Analysis, Nonlinear truss, Solar Sail## Resumo

We propose a nonlinear dynamic study of a solar sail model, to understand the structural

response of large lightweight appendages in space environment and to set an adequate procedure to

simulate one. Initially, a static linear/nonlinear analysis is carried out using the commercial software

ABAQUS® and an implemented nonlinear algorithm to determine the limit conditions of this structure.

After that, we perform a dynamic simulation in order to determine the real impact of the nonlinear

assumption in the final response of this lightweight model. The numerical algorithm is written in

MATLAB® language and based on a ‘composite scheme’, where the first sub-step solution is obtained

via the trapezoidal rule, and for the second sub-step solution, a 3-point Euler backward formula is

employed. The dynamic equilibrium at each load step is achieved via a path following methodology,

seeking to solve the nonlinear systems of equations derived from the time integration procedure. The

proposed 450m2

solar sail is modelled as a kite-shape structure, consisting of four-swallow lattice

members kept in the cross configuration by guyed cables, each one modeled with nonlinear space truss

elements. To represent working conditions, solar wind pressure is applied at the upmost elements of

the lattice members in conjunction with a set of concentrated forces at the corners of the cross

configuration to represent the cables linking the appendage to a supposed mother spacecraft/satellite.