Aeroelasticity and Structural Dynamics

Overview

The Aeroelasticity and Structural Dynamics IPT is responsible for the design, analysis and simulation of the main components of the aerostructure, using both numerical and experimental methods. Finite element models (FEM) are the most important tool for investigating the structural behaviour of the rocket. Our research focuses mainly on designing the lamination sequence of the composite parts, such as tanks manufactured using filament winding technology, and on understanding the structural response of the rocket through the analysis of its natural frequencies and sloshing, as well as its response to the engine and parachute loads. Particular attention is given to the flutter phenomenon, for which we developed a dedicated code to assess the structural integrity of the fins throughout the ascent phase.

Composite Design

We conduct CFD simulations across a spectrum of boundary conditions that represent various flight parameters, including velocity, pressure, and altitude. We examine different flight scenarios, such as steady-state flows, and consider both compressible and incompressible regimes, as well as subsonic and supersonic speeds. Additionally, our team performs plume simulations to analyze the behavior of motor exhaust and its interaction with external airflow, essential for understanding the overall aerodynamic performance. Upon completing the simulations, we evaluate convergence and perform detailed post-processing to extract aerodynamic coefficients, pressure distributions, and flow visualizations.

Parachute Loads

The pulling forces generated on the parachute deployment are the most critical situation in the descent phase. The rocket experiences a complex state of stress due to high axial forces and bending moments. Over the years we developed a code which incorporates a parachute opening model with a structural, simplified dynamic model of the rocket. This code is updated annually to refine the simulations and the opening forces peaks are then used in the finite element analyses of the rocket’s flanges.

Flutter

Flutter is a destructive phenomenon caused by the coupling between aerodynamic forces and deformation of the fins. Therefore, fins must be stiff enough to prevent the loss of the rocket. We analyze flutter in different ways: through a dedicated Matlab code called AeroElasticFins and through commercial softwares that exploit panel methods to model the aerodynamic forces. In both approaches, we ensure that any instability does not occur throughout the whole flight, in all Mach regimes.

Sloshing and Digital Twin

Dynamic phenomena might affect the rocket’s performance. Special attention is given to the analysis of the rocket’s natural frequencies, for which a complete numerical copy (called digital twin) is developed to calculate the structural response to different loading conditions. Another crucial aspect to be taken into account is sloshing: variations in the rocket’s center of gravity due to the movements of the fluids in the tanks might reduce stability. This kind of interaction is deeply investigated using both analytical and numerical approaches.

Requirements

Base

  • Theoretical knowledge of structural mechanics (with particular attention to composite materials)
  • Basic knowledge of aerodynamics
  • Basic knowledge of Matlab, Python or similar programming languages for scientific computing

Advanced

  • Solid knowledge of structural mechanics and dynamics
  • Solid knowledge of aeroelastic phenomena
  • Experience with finite element commercial softwares such as Abaqus, Femap, Nastran…