scholarly journals LUMPED-ELEMENT ANALYSIS OF AN ELECTROSTATIC SQUEEZE-FILM MEMS DROPLET EJECTOR

2010 ◽  
Author(s):  
E.P. Furlani ◽  
H.V. Panchawagh ◽  
T.L. Sounart
Keyword(s):  
Squeeze Film ◽  
Element Analysis ◽  
Lumped Element ◽  
Droplet Ejector

Wear Characteristics of Conventional and Squeeze-Film Artificial Hip Joints

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
S. Boedo ◽  
S. A. Coots
Keyword(s):  
Implant Design ◽  
Squeeze Film ◽  
Linear Wear ◽  
Wear Depth ◽  
Element Analysis ◽  
Wear Characteristics ◽  
Wear Rates ◽  
Cycle Loading ◽  
Artificial Hip Joints ◽  
Elastic Elements

This paper investigates the wear characteristics of a novel squeeze-film hip implant design. Key features of the design are elastic elements attached to the cup which provide a mechanical means for ball separation during the swing phase of the gait loading cycle. An Archard-based wear formulation was implemented utilizing the ansys finite element analysis program which relates contact pressure and sliding distance to linear wear depth. It is found that low-modulus elastic elements with bonded high-modulus metal coatings offer significant predicted improvement in linear and volumetric wear rates when compared with conventional implant geometries for gait cycle loading and kinematic conditions found in practice.

Lumped‐element analysis of a fluid‐loaded pipe‐hull coupling

2000 ◽  
Vol 107 (5) ◽  
pp. 2800-2800
Author(s):  
Jayme J. Caspall ◽  
Minami Yoda ◽  
Peter H. Rogers
Keyword(s):  
Element Analysis ◽  
Lumped Element

Squeeze film dampers supporting high-speed rotors: Rotordynamics

2020 ◽  
pp. 135065012092208
Author(s):  
Sina Hamzehlouia ◽  
Kamran Behdinan
Keyword(s):  
Finite Element ◽  
Steady State ◽  
Gas Turbines ◽  
High Speed ◽  
Squeeze Film ◽  
Jet Engines ◽  
Transient Vibration ◽  
Element Analysis ◽  
Squeeze Film Damper ◽  
The Time Domain

This work develops a finite element based multi-mass flexible rotor model for theoretical investigation of the influence of the squeeze film damper lubricant inertia on the unbalance-induced steady-state and transient vibration amplitudes of high speed turbomachinery. The rotordynamic model is developed by applying the principles of finite element analysis to discretize the rotor components, including the rotor shaft and disk, into local elements with mass, stiffness, and gyroscopic matrices. Subsequently, the local matrices are assembled together to develop the global model of the rotordynamic system. The influence of squeeze film damper lubricant inertia is incorporated into the model by using short-length cavitated damper models with retaining springs executing circular-centered orbits. Additionally, the rotordynamic model incorporating the nonlinear squeeze film damper models is iteratively solved in the time domain by applying a predictor-corrector transient modal integration numerical method and the steady-state and transient motions of the rotor system are investigated under different rotor and squeeze film damper parameters. The results of the study verify the substantial influence of squeeze film damper lubricant inertia on attenuating the vibrations of high-speed turbomachinery. Furthermore, the developed rotordynamic model delivers an efficient and powerful platform for the analysis of high-speed turbomachinery, including jet engines and gas turbines.

Nonlinear Identification of a Capacitive Dual-Backplate MEMS Microphone

2005 ◽  
Author(s):  
Jian Liu ◽  
David T. Martin ◽  
Karthik Kadirvel ◽  
Toshikazu Nishida ◽  
Mark Sheplak ◽  
...  
Keyword(s):  
Nonlinear System Identification ◽  
Nonlinear Least Squares ◽  
Order System ◽  
Multiple Time Scales ◽  
Model Parameters ◽  
Multiple Time ◽  
Element Analysis ◽  
System Parameters ◽  
Lumped Element ◽  
Mems Microphone

This paper presents the nonlinear system identification of model parameters for a capacitive dual-backplate MEMS microphone. System parameters of the microphone are developed by lumped element modeling (LEM) and a governing nonlinear equation is thereafter obtained with coupled mechanical and electrostatic nonlinearities. The approximate solution for a general damped second order system with both quadratic and cubic nonlinearities and a non-zero external step loading is explored by the multiple time scales method. Then nonlinear finite element analysis (FEA) is performed to verify the accuracy of the lumped stiffnesses of the diaphragm. The microphone is characterized and nonlinear least-squares technique is implemented to identify system parameters from experimental data. Finally uncertainty analysis is performed. The experimentally identified natural frequency and nonlinear stiffness parameter fall into their theoretical ranges for a 95% confidence level respectively.

scholarly journals Sensitivity and Performances Analysis of a Dynamic Pressure Narrow-Band Electrodynamic Micro-Sensor

2020 ◽  
Vol 25 (1) ◽  
pp. 17-26
Author(s):  
Mohamed Hadj Said ◽  
Fares Tounsi ◽  
Libor Rufer ◽  
Brahim Mezghani ◽  
Laurent A. Francis
Keyword(s):  
Resonant Frequency ◽  
Dynamic Pressure ◽  
Dynamic Performance ◽  
Element Model ◽  
Element Analysis ◽  
Lumped Element ◽  
Sensitivity Curves ◽  
Micro Sensor ◽  
Lumped Element Model ◽  
Different Diameters

This paper presents analytic and numerical modelling of a MEMS electrodynamic micro-sensor of dynamic pressure. Two coaxial planar inductors of different diameters are used in the proposed micro-sensor design. Using finite element analysis, the diaphragm resonant frequency and dynamic displacements are evaluated for different diaphragm thicknesses. Then, the total sensitivity is deduced by coupling different physical domains which contribute in the micro-sensor operation. A lumped element model is built in order to study the micro-sensor sensitivity and define the dynamic performance for different resonant frequencies. This model shows that the best sensitivity, within the mV/Pa range, is obtained around the resonant frequency when operation in the audible frequency range, and decreases to the uV/Pa range for ultrasonic frequencies. The obtained sensitivity curves prove that the undamped inductive micro-sensor can offer high pressure sensitivity within a narrow frequency bandwidth.

Squeeze Film Damper Bearing With Double-Ended Beam Centering Springs: Part I — Design and Analysis

2020 ◽  
Author(s):  
Wei Li ◽  
Christopher Braman ◽  
Brian Hantz ◽  
Manish Thorat ◽  
Brian Pettinato
Keyword(s):  
Dynamic Performance ◽  
Squeeze Film ◽  
Spring Stiffness ◽  
Element Analysis ◽  
Squeeze Film Damper ◽  
Wide Range ◽  
Bearing Design ◽  
Parametric Finite Element Analysis ◽  
Rotor Dynamic ◽  
Additional Safety

Abstract Squeeze film damper (SFD) bearings are widely used in industry to enhance rotor dynamic stability in super-critical applications. This study examines an SFD bearing design with double-ended beam centering springs placed external to the squeeze film and in parallel with O-ring seals. The purpose of the new SFD bearing design is to minimize the use of O-rings as a support and centering device, instead relying on compact external springs that can be independently adjusted to ensure centered operation. The new design is applicable to a wide range of bearing sizes and rotor weights with variable spring stiffness, damping value and envelope dimensions. Spring stiffness and stress coefficients were generated for 3.5-inch bearing and SFD assembly from a parametric finite element analysis (FEA). High cycle fatigue of the springs was evaluated using the Soderberg criterion with an additional safety factor. Rotor-dynamic performance of the new design was analyzed using an historical rotor applying both π-film and full-film models. To evaluate the design, the same 3.5 inch SFD bearing presented in this study was manufactured and tested in succeeding work.

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