Dynamic Model Development and Analysis of Multiple Rotors Coupled With Thrust Collars

2018 ◽  
Author(s):  
Kyungdae Kang
Keyword(s):  
Gear Tooth ◽  
Model Development ◽  
Element Model ◽  
Fe Model ◽  
Rotor Design ◽  
Force Direction ◽  
Vibration Responses ◽  
Frequency Components ◽  
Forced Vibration Analysis ◽  
Transmitted Frequency

The core model of integrally geared centrifugal compressor/expander equipped with thrust collars is developed using finite element model. Each rotor model is coupled through the equivalent stiffness due to thrust collar and the gear web. Subsynchronous vibration caused by the transmitted frequency components from other shafts is analyzed through forced vibration analysis. Unlike conventional frequency response function (FRF), directional FRF technique is adopted because rotordynamic analysis requires that forward and backward mode responses should be identified according to the rotational force direction exerted on the rotor. Previous analysis results utilizing 3D FE model of geared rotors equipped with thrust collars revealed that transmitted vibration level is mostly affected by thrust collars, rather than gear tooth. The rotordynamic model developed in this paper ensures reliability and efficiency in the multi-rotor design equipped with thrust collars providing a systematic way to analyze the multi-rotor vibration responses due to the transmitted forces from one shaft to the other.

Automated Segmentation of Swine Skulls for Finite Element Model Creation Using High Resolution μ-CT Images

2019 ◽  
Vol 16 (03) ◽  
pp. 1842012 ◽  
Author(s):  
Zimo Zhu ◽  
Donna C. Jones ◽  
G. R. Liu ◽  
Sajjad Soleimani ◽  
Xu Huang ◽  
...  
Keyword(s):  
Finite Element ◽  
Material Properties ◽  
Complex Structure ◽  
Model Development ◽  
Element Model ◽  
Fe Model ◽  
Micro Computed Tomography ◽  
Mineral Density ◽  
Detailed Model ◽  
Bone Mineral Density Loss

Finite element (FE) analysis has been widely used to investigate bone responses to mechanical loading. Research in long bones has been straight forward because modeling of these bones requires only two material properties. Such an FE model may provide an adequate approximation of the anatomy for many cases. However, a more detailed model of skull bones is needed to accurately capture its complex structure of multiple bone pieces and the various mineral densities distributed throughout these bone pieces. Unfortunately, FE model development incorporating both complex geometries and anatomically accurate material properties is both computationally and labor intensive. In this study, a method is proposed to automatically segment micro-computed tomography ([Formula: see text]-CT) scan images of bone pieces to build an FE model of a full swine hemi-skull. Using the Digital Imaging and Communications in Medicine (DICOM) files from scanned bones, the complete geometry of each bone piece is recreated through seven customized processing algorithms. After assembling the bone pieces to form the skull, experimentally derived Young’s modulus values are correlated to grayscale values to produce a detailed FE model for accurate simulation. This detailed skull model can be used to predict strain/stress patterns in response to various loading regimes to facilitate research questions in fracture healing and growth, as well as bone tissue engineering and bone mineral density loss (e.g., osteoporosis).

Vibrational and Acoustical Analysis of Trussed Railroad Bridge Under Moving Loads

2012 ◽  
Author(s):  
R. Daniel Costley ◽  
Henry Diaz-Alvarez ◽  
Mihan H. McKenna
Keyword(s):  
Structural Damage ◽  
Current Model ◽  
Element Model ◽  
Vehicle Suspension ◽  
Fe Model ◽  
Vibrational Modes ◽  
Moving Loads ◽  
Vehicle Loading ◽  
Vibration Responses ◽  
Railroad Bridge

A Finite Element model has been developed for a Pratt truss railroad bridge located at Ft. Leonard Wood, MO. This model was used to investigate the vibration responses of a bridge under vehicle loading. Modeling results have been obtained for a single axle with two wheels traversing the bridge at different speeds. The current model does not include the effects of vehicle suspension. Superposition of multiple axles has been used to represent a locomotive transiting the bridge. The output of the vibration response was used as an input to an acoustic FE model to determine which vibrational modes radiate infrasound. The vibration and acoustic models of the railroad bridge will be reviewed, and results from the analysis will be presented. Measurements from an accelerometer mounted on the bridge agree reasonably well with model results. Infrasound could potentially be used to remotely provide information on the capacity and number of the vehicles traversing the bridge and to monitor the bridge for significant structural damage.

Finite Element Analysis of the Distributed Vibration Absorbers for Structural Noise Control

2005 ◽  
Author(s):  
Ashwini Gautam ◽  
Chris Fuller ◽  
James Carneal
Keyword(s):  
Finite Element ◽  
Numerical Model ◽  
Base Plate ◽  
Element Model ◽  
Fe Model ◽  
Vibration Absorbers ◽  
Element Analysis ◽  
Poroelastic Media ◽  
Hexahedral Elements ◽  
Component Models

This work presents an extensive analysis of the properties of distributed vibration absorbers (DVAs) and their effectiveness in controlling the sound radiation from the base structure. The DVA acts as a distributed mass absorber consisting of a thin metal sheet covering a layer of acoustic foam (porous media) that behaves like a distributed spring-mass-damper system. To assess the effectiveness of these DVAs in controlling the vibration of the base structures (plate) a detailed finite elements model has been developed for the DVA and base plate structure. The foam was modeled as a poroelastic media using 8 node hexahedral elements. The structural (plate) domain was modeled using 16 degree of freedom plate elements. Each of the finite element models have been validated by comparing the numerical results with the available analytical and experimental results. These component models were combined to model the DVA. Preliminary experiments conducted on the DVAs have shown an excellent agreement between the results obtained from the numerical model of the DVA and from the experiments. The component models and the DVA model were then combined into a larger FE model comprised of a base plate with the DVA treatment on its surface. The results from the simulation of this numerical model have shown that there has been a significant reduction in the vibration levels of the base plate due to DVA treatment on it. It has been shown from this work that the inclusion of the DVAs on the base plate reduces their vibration response and therefore the radiated noise. Moreover, the detailed development of the finite element model for the foam has provided us with the capability to analyze the physics behind the behavior of the distributed vibration absorbers (DVAs) and to develop more optimized designs for the same.

scholarly journals Bond Behaviour of Near-Surface Mounted Strips in RC Beams—Experimental Investigation and Numerical Simulations

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4362
Author(s):  
Renata Kotynia ◽  
Hussien Abdel Baky ◽  
Kenneth W. Neale
Keyword(s):  
Concrete Strength ◽  
Element Model ◽  
Steel Reinforcement ◽  
Reinforcement Ratio ◽  
Experimental Program ◽  
Fe Model ◽  
Bond Behaviour ◽  
Near Surface ◽  
Cfrp Laminates ◽  
Near Surface Mounted

This paper presents an investigation of the bond mechanism between carbon fibre reinforced polymer (CFRP) laminates, concrete and steel in the near-surface mounted (NSM) CFRP-strengthened reinforced concrete (RC) beam-bond tests. The experimental program consisting of thirty modified concrete beams flexurally strengthened with NSM CFRP strips was published in. The effects of five parameters and their interactions on the ultimate load carrying capacities and the associated bond mechanisms of the beams are investigated in this paper with consideration of the following investigated parameters: beam span, beam depth, longitudinal tensile steel reinforcement ratio, the bond length of the CFRP strips and compressive concrete strength. The longitudinal steel reinforcement was cut at the beam mid-span in four beams to investigate a better assessment of the influence of the steel reinforcement ratio on the bond behaviour of CFRP to concrete bond behaviour. The numerical analysis implemented in this paper is based on a nonlinear micromechanical finite element model (FEM) that was used for investigation of the flexural behaviour of NSM CFRP-strengthened members. The 3D model based on advanced CFRP to concrete bond responses was introduced to modelling of tested specimens. The FEM procedure presents the orthotropic behaviour of the CFRP strips and the bond response between the CFRP and concrete. Comparison of the experimental and numerical results revealed an excellent agreement that confirms the suitability of the proposed FE model.

Finite Element Model of Human Cochlea Considering of the Helicotrema Size

2013 ◽  
Vol 456 ◽  
pp. 576-581 ◽  
Author(s):  
Li Fu Xu ◽  
Na Ta ◽  
Zhu Shi Rao ◽  
Jia Bin Tian
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Basilar Membrane ◽  
Round Window ◽  
Element Model ◽  
Oval Window ◽  
Fe Model ◽  
Cochlear Duct ◽  
Human Cochlea ◽  
Set Up

A 2-D finite element model of human cochlea is established in this paper. This model includes the structure of oval window, round window, basilar membrane and cochlear duct which is filled with fluid. The basilar membrane responses are calculated with sound input on the oval window membrane. In order to study the effects of helicotrema on basilar membrane response, three different helicotrema dimensions are set up in the FE model. A two-way fluid-structure interaction numerical method is used to compute the responses in the cochlea. The influence of the helicotrema is acquired and the frequency selectivity of the basilar membrane motion along the cochlear duct is predicted. These results agree with the experiments and indicate much better results are obtained with appropriate helicotrema size.

A coupled FE model for the joint resolution of the shallow water and the groundwater flow equations

2014 ◽  
Vol 24 (7) ◽  
pp. 1553-1569 ◽  
Author(s):  
H.G. Rábade ◽  
P. Vellando ◽  
F. Padilla ◽  
R. Juncosa
Keyword(s):  
Groundwater Flow ◽  
Shallow Water ◽  
Free Surface Flow ◽  
Element Model ◽  
Surface Flow ◽  
Fe Model ◽  
Content Type ◽  
Flow Equations ◽  
Natural Watersheds ◽  
Joint Resolution

Purpose – A new coupled finite element model has been developed for the joint resolution of both the shallow water equations, that governs the free surface flow, and the groundwater flow equation that governs the motion of water through a porous media. The paper aims to discuss these issues. Design/methodology/approach – The model is based upon two different modules (surface and ground water) previously developed by the authors, that have been validated separately. Findings – The newly developed software allows for the assessment of the fluid flow in natural watersheds taking into account both the surface and the underground flow in the way it really takes place in nature. Originality/value – The main achievement of this work has dealt with the coupling of both models, allowing for a proper moving interface treatment that simulates the actual interaction that takes place between surface and groundwater in natural watersheds.

Dynamic – Thermal Analyses of a Structurally Reconfigured Electronics Package Onboard Mini Satellite

2014 ◽  
Vol 592-594 ◽  
pp. 2117-2121 ◽  
Author(s):  
P. Veeramuthuvel ◽  
S. Jayaraman ◽  
Shankar Krishnapillai ◽  
M. Annadurai ◽  
A.K. Sharma
Keyword(s):  
Finite Element ◽  
Printed Circuit Board ◽  
Thermal Environment ◽  
Thermal Analyses ◽  
Simulation Models ◽  
Element Model ◽  
Circuit Board ◽  
Element Analysis ◽  
Transfer Path ◽  
Vibration Responses

The electronics package in a spacecraft is subjected to a variety of dynamic loads during launch phase and suitable thermal environment for the mission life. The dynamic and thermal analyses performed for a structurally reconfigured electronics package. Two different simulation models are developed to carry out the analyses. This paper discusses in two parts, in part-1, the vibration responses are determined at various critical locations, including on the Printed Circuit Board (PCB) for the vibration loads specified by launch vehicle using Finite Element Analysis (FEA). The mechanical properties of PCB are determined from the test specimens, which are then incorporated in the finite element model. In part-2, the steady-state temperature distributions on the components and on the PCB are determined, to check the effectiveness of heat transfer path from the components to the base of the package and to verify the predicted values are within the acceptable temperature limits specified. The predicted temperature values are then compared with on-orbit observations.

scholarly journals Planetary Gearbox Dynamic Modeling Considering Bearing Clearance and Sun Gear Tooth Crack

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2638
Author(s):  
Xianhua Chen ◽  
Xingkai Yang ◽  
Ming J. Zuo ◽  
Zhigang Tian
Keyword(s):  
Dynamic Model ◽  
Dynamic Modeling ◽  
Failure Modes ◽  
Gear Tooth ◽  
Working Environment ◽  
The Sun ◽  
Planetary Gearbox ◽  
Bearing Clearance ◽  
Vibration Responses ◽  
Planet Gear

Planetary gearbox systems are critical mechanical components in heavy machinery such as wind turbines. They may suffer from various failure modes, due to the harsh working environment. Dynamic modeling is a useful method to support early fault detection for enhancing reliability and reducing maintenance costs. However, reported studies have not considered the sun gear tooth crack and bearing clearance simultaneously to analyze their combined effect on vibration characteristics of planetary gearboxes. In this paper, a dynamic model is developed for planetary gearboxes considering the clearance of planet gear, sun gear, and carrier bearings, as well as sun gear tooth crack levels. Bearing forces are calculated considering bearing clearance, and the dynamic model equations are updated accordingly. The results reveal that the combination of bearing clearances can affect the vibration response with sun gear tooth crack by increasing the kurtosis. It is found that the effect of planet gear bearing clearance is very small, while the sun gear and carrier bearing clearance has clear impact on the vibration responses. These findings suggest that the incorporation of bearing clearance is important for planetary gearbox dynamic modeling.

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