geometrical nonlinearities
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Structures ◽  
2021 ◽  
Vol 33 ◽  
pp. 1967-1986
Author(s):  
Behzad Mohammadzadeh ◽  
Young Jong Kang ◽  
Seungjun Kim ◽  
Marina MS Cabral-Pinto ◽  
Zahra Derakhshan Nejad

Actuators ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 21
Author(s):  
Andrea Opreni ◽  
Nicolò Boni ◽  
Roberto Carminati ◽  
Attilio Frangi

In this work, we address the simulation and testing of MEMS micromirrors with hardening and softening behaviour excited with patches of piezoelectric materials. The forces exerted by the piezoelectric patches are modelled by means of the theory of ferroelectrics developed by Landau–Devonshire and are based on the experimentally measured polarisation hysteresis loops. The large rotations experienced by the mirrors also induce geometrical nonlinearities in the formulation up to cubic order. The solution of the proposed model is performed by discretising the device geometry using the Finite Element Method, and the resulting large system of coupled differential equations is solved by means of the Harmonic Balance Method. Numerical results were validated with experimental data collected on the devices.


AIAA Journal ◽  
2019 ◽  
Vol 57 (8) ◽  
pp. 3524-3533 ◽  
Author(s):  
A. Pagani ◽  
E. Carrera ◽  
R. Augello

Author(s):  
Anthony Picou ◽  
Evangéline Capiez-Lernout ◽  
Christian Soize ◽  
Moustapha Mbaye

Abstract This work concerns the nonlinear numerical analysis of mistuned blades for a rotating detuned bladed-disk structure with geometrical nonlinearities. The detuning phenomenon is taken into account through a deterministic approach by modifying material properties of some blades. A nonlinear reduced-order model is obtained by setting up a basis using a double projection method. The mistuning uncertainties are implemented through a nonparametric probabilistic approach for which the level of uncertainties is controlled by a hyperparameter. A numerical application is carried out on a bladed-disk structure made up of 24 blades whose finite element model has about 800,000 dofs exhibiting complex dynamic behaviors.


2019 ◽  
Vol 123 (1264) ◽  
pp. 912-946 ◽  
Author(s):  
E. M. Amato ◽  
C. Polsinelli ◽  
E. Cestino ◽  
G. Frulla ◽  
N. Joseph ◽  
...  

AbstractExperimental and numerical investigations into the linear and nonlinear aeroelastic behaviour of very flexible High Altitude Long Endurance (HALE) wings are conducted to assess the effect of geometrical nonlinearities on wings displaying moderate-to-large displacement. The study shows that the dynamic behaviour of wings under large deflection, and specifically the edgewise and torsion natural frequencies and modal characteristics, are largely affected by the presence of geometrical nonlinearities. A modular wing structure has been manufactured by rapid prototyping and it has been tested to characterise its dynamic and aeroelastic behaviour. At first, several simple isotropic cantilever beams with selected crosssections are numerically investigated to extract their modal characteristics. Experiments are subsequently conducted to validate the geometrically nonlinear dynamics behaviour due to high tip displacement and to understand the influence of the beam cross-section geometry. The structural dynamics and aeroelastic analysis of a very flexible modular selected wing is then investigated. Clean-wing wind-tunnel tests are carried out to assess flutter and dynamic response. The wind-tunnel model display interesting aeroelastic features including the substantial influence of the wing large deformation on its natural frequencies and modal characteristics.


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