Nonlinear reduced-order model for vertical sloshing by employing neural networks

Marco Pizzoli,Franco Mastroddi,Jon Martinez-Carrascal,Francesco Saltari,Leo M González-Gutiérrez

doi:10.1007/s11071-021-06668-w

Marco Pizzoli, Franco Mastroddi + Show 3 more

Open Access

https://doi.org/10.1007/s11071-021-06668-w

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Abstract

The aim of this work is to provide a reduced-order model to describe the dissipative behavior of nonlinear vertical sloshing involving Rayleigh–Taylor instability by means of a feed forward neural network. A 1-degree-of-freedom system is taken into account as representative of fluid–structure interaction problem. Sloshing has been replaced by an equivalent mechanical model, namely a boxed-in bouncing ball with parameters suitably tuned with performed experiments. A large data set, consisting of a long simulation of the bouncing ball model with pseudo-periodic motion of the boundary condition spanning different values of oscillation amplitude and frequency, is used to train the neural network. The obtained neural network model has been included in a Simulink® environment for closed-loop fluid–structure interaction simulations showing promising performances for perspective integration in complex structural system.

Highlights

Vertical sloshing is a phenomenon that occurs on structures that undergo strong vertical accelerations
The goal of this paper was to study and provide a reduced-order model to describe the dissipative behavior of nonlinear vertical sloshing of fuel-inside-wing tanks by means of a feed forward neural network
The data used to build an equivalent mechanical model (EMM) was provided by an experimental study about the coupling between fluid sloshing and a 1-DoF system performed at Universidad Politécnica de Madrid (UPM)

Summary

Introduction

Vertical sloshing is a phenomenon that occurs on structures that undergo strong vertical accelerations. The jolt of fuel generally stowed in the wings caused by vertical accelerations is coupled with the structural dynamics of the aircraft. This type of sloshing is well known to provide a noticeable increase in structural damping but remains generally not modeled in the design phase of modern aircraft. Vertical slosh dynamics is one of the possible dynamics of the fluid stowed in the tanks which, when it occurs, manifests different characteristics compared to the classic sloshing, generally occurring with rotations and lateral motion of the tank The latter generates standing waves inside the cavity that provide dynamic coupling with structure and possible modification of flutter margins.

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