Session: 02-05-01: Experimental Studies in Structural Dynamics

Paper Number: 161969

161969 - A Multi-Mode Vibration-Based Technique for Impact Dynamics Reconstruction 

In space engineering, the study of impacts between bodies is crucial for understanding and mitigating the effects of high-velocity collisions encountered by flight hardware during space operations. The study of impacts between bodies and the reconstruction of the resulting forces are pivotal both for estimating the in-flight environment harshness (micro-meteoroids, space debris etc.) and for designing and testing safe, reliable, and efficient systems. Impact events, either between solid objects, components, or structures, are common especially in the form of high-speed collisions or sudden loading conditions, frequently triggering structural vibrations. These events can range from minor collisions to catastrophic accidents, and understanding the forces involved is essential to designing systems that can deal with such incidents. The nature of these impacts depends on factors such as relative velocity, material properties, structural characteristics and constraints of the bodies involved.

The measurement of an impactive force is a challenging task, which has to cope with the complex dynamic response of the impacted structure, involving  stress waves travelling through the body. Advanced methodologies, such as inverse problem solving, sensor fusion techniques and machine learning algorithms are increasingly used to enhance the accuracy and reliability of force reconstruction methods. These methodologies, however, either rely on the impacted body transfer function (whose experimental prediction requires extensive sensor networks and calibration tests), either are significantly affected by the noise level and by the number of sensors used to reconstruct the driving force or require a large amount of labeled data to train machine learning algorithms effectively.

The force reconstruction technique hereby presented exploits the multi-mode response of the impacted body, accounting for its deformation and non-linearities. The technique includes a  FE model of the impacted body to estimate its modal parameter, and an optimal filter to estimate its mode oscillation amplitudes after the impact event. Each vibration mode corresponds to a dynamical system whose steady-state oscillations are ruled by the shape, magnitude and duration of the impactive force.  As more vibration modes are detected, the accuracy of force reconstruction improves. However, even when only a few modes are considered, it is still possible to accurately estimate the momentum exchanged during the impact and the duration of the event. The technique does not require the estimation of the sensing body transfer function, nor any prior knowledge of the impactive force and does not include any additional constraints on the impacted body model. The technique can also be easily adapted to situations where the impacted body is initially constrained, as well as to the estimation of the momentum acquired by a body following the relaxation of an initial preloading.

The technique is first evaluated through simulations, where impacts are tested on a space-related case study. Following this, a dedicated experimental setup is developed at the University of Trento to conduct a comprehensive campaign using a real-world case study, accounting for measurement uncertainties. Finally, the results are presented and future development discussed.

Presenting Author: Edoardo Dalla Ricca University of Trento

Presenting Author Biography: Edoardo Dalla Ricca is a postdoctoral fellow at the University of Trento (Italy). His main research interests include the development of mechatronic technologies for Gravitational Reference Systems and the characterization of adhesion between gold surfaces in space environment.

He has also served as a Visiting Researcher at Texas A&M University (USA) and has a Ph.D. in Mechatronics and Systems Engineering.