0000000000434656
AUTHOR
Alexandre Loredo
Study and Simulation of Helicopter Gearboxes Noise
International audience; Main gearbox is one of the main noise sources in helicopter cabin. In order to improve the comfort of customers and reduce the health impact, acoustic and vibration mechanisms of gearboxes have to be understood and simulated during development phases. Thus, we first present the global methodology chosen to compute main gearboxes noise in helicopter cabins. Secondly, we described the way we compute mechanical excitation sources induced from gear mesh, static transmission error and meshing stiffness. Depending on the type of gear, we compute those using either analytical specially developed code or EC codes. Thirdly, we propose a modeling to compute dynamic loads on be…
Characterization of the Dynamic Interaction between Chassis and Powertrain of a Vehicle Using the Coupling Matrix
International audience; This study is concerned with the vibration transmission between two subsystems of a vehicle: the chassis which is considered as an elastic structure and the powertrain which is considered as a rigid body. The study is carried out based on a new coupling matrix constructed from equations of dynamic behavior of each subsystems. This matrix depends only on the impedance matrices of the two subsystems and the mechanical characteristics of the linking mounts. Under some assumptions, a simplified expression to obtain the overall behaviour of the entire system is proposed. Despite its sensitivity to the degree of coupling between the subsystems, this method can be applied t…
Transverse shear warping functions for anisotropic multilayered plates
In this work, transverse shear warping functions for an equivalent single layer plate model are formulated from a variational approach. The part of the strain energy which involves the shear phenomenon is expressed in function of the warping functions and their derivatives. The variational calculus leads to a differential system of equations which warping functions must verify. Solving this system requires the choice of values for the (global) shear strains and their derivatives. A particular choice, which is justified for cross-ply laminates, leads to excellent results. For single layer isotropic and orthotropic plates, an analytical expression of the warping functions is given. They invol…
Vibroacoustic Simulation of Heterogeneous Multilayer Composite Plates Involving Low Young's Modulus Viscoelastic Material
The vibroacoustic behavior of composite multilayered plates involving high Young’s modulus ratios between adjacent layers, like sandwich panels and passive constrained layer damped plates, is studied. As classical plate models give poor results with such structures, a specific model has been used. It is an equivalent single layer model, with a five unknown displacement field which takes into account a variation of transverse shear strains into the thickness. A classical sandwich structure is simulated, its natural frequencies are compared to those given by other models and a 3D finite element simulation which is taken as reference. A second study concerns a composite plate with a damping pa…
Dynamic Coupling Study between Substructures. Application to the Chassis-Powertrain Interaction
International audience