We numerically study a one-dimensional,nonlinear lattice model which in the linear limit is relevant to the study of bending (flexural) waves.In contrast with the classic one-dimensional mass-spring system,the linear dispersion relation of the considered model has different characteristics in the low frequency limit.By introducing disorder in the masses of the lattice particles,we investigate how different nonlinearities in the potential (cubic,quadratic,and their combination)lead to energy delocalization,equipartition,and chaotic dynamics.We excite the lattice using single site initial momentum excitations corresponding to a strongly localized linear mode and increase the initial energy of excitation.Beyond a cer-tain energy threshold,when the cubic nonlinearity is present,the system is found to reach energy equipartition and total delocalization.On the other hand,when only the quartic nonlinearity is activated,the system remains localized and away from equipartition at least for the energies and evolution times considered here.However,for large enough energies for all types of nonlinearities we observe chaos.This chaotic behavior is combined with energy delocalization when cubic non-linearities are present,while the appearance of only quadratic nonlinearity leads to energy localization.Our results reveal a rich dynamical behavior and show differences with the relevant Fermi-Pasta-Ulam-Tsingou model.Our findings pave the way for the study of models relevant to bending (flexural) waves in the presence of nonlinearity and disorder,anticipating different energy transport behaviors.

Nonlinear Dynamics and Chaos Group,Department of Mathematics and Applied Mathematics,University of Cape Town,Rondebosch 7701,South Africa;Laboratoire d'Acoustique de l'Université du Mans (LAUM),UMR 6613,Institut d'Acoustique-Graduate School (IA-GS),CNRS,Le Mans Université,France

[1]Arnold Ngapasare;Georgios Theocharis;Olivier Richoux;Vassos Achilleos;Charalampos Skokos-.Energy spreading,equipartition,and chaos in lattices with non-central forces)[J].中国物理B（英文版）,2022(02):131-141

quartic

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