Master thesis and internship[BR]- Master's thesis : Nonlinear vibrations in a piccolo tube: Study of the correspondence between experimental and numerical results[BR]- Integration Internship

Abstract

Nonlinear behaviours are inherent to today’s aerospace industry due in part to the many contemporary constraints. This master thesis focuses on the study of such a nonlinearity by investigating the behaviour of a piccolo tube subjected to different types of external excitations. For this purpose, experimental tests are conducted on the corresponding physical structure on the one hand. On the other hand, similar results are attempted to be obtained using NI2D, a numerical simulation software adapted to the study of nonlinearities. This study is also in the continuation of results obtained in previous analyses. To this purpose, the structure is studied when subjected to sine sweep and randoms excitations. Methods are also implemented to extract and compare the stress levels to which the tube is subjected. The obtained results confirm the previous sine sweep findings. The methods used also allow a good correspondence between the two types of results for random excitations. Limitations must, however, be taken into account, in this case, when nonlinearity is reached due to a numerical over-representation of harmonics triggering. Finally, similar stress levels can be achieved for numerical tests and simulations outside resonance peaks. However, due to discrepancies, other numerical methods should be considered to obtain the stresses in the frequency band of the resonance peak, such as directly computing this data on a whole time signal. This could moreover allow the correspondence of the two types of stress results for random excitation.