Advanced multibody dynamics formulations for space applications: from theory to implementation

Recently, the interest of the space agencies in missions involving the soft-landing of a spacecraft on the surface of moons, planets, asteroids and comets is growing. Modern CAE tool can extensively improve the design of such complex systems. Nevertheless few multibody codes are tailored for space applications. DCAP is a multibody software widely used by the European Space Agency over the last 30 years and specifically produced for the dynamic analysis of space mechanisms. In order to perform a dynamic analysis of a soft-landing of a spacecraft, particular features need to be available. The focus of this thesis is the development, from theory to implementation, of innovative features for the multibody DCAP software in order to extend its simulation capabilities. DCAP is established on a recursive multibody formulation based on Maggi-Kane’s equations. Quaternions have been implemented in DCAP code in order to avoid the gimbal lock singularity generated from the use of the Euler angles. A modern numerical integrator with variable step size and variable order has been studied and added to the DCAP solver options. Three different contact types have been formulated and implemented and an extensive review of the most widespread dry friction force models has been accomplished. A multibody simulation of a soft-landing of a spacecraft on the surface of an asteroid is reported to highlight the benefits of the developments implemented. A second numerical simulation has been investigated to illustrate a modelling approach for studying multiple closed loop topology systems