scholarly journals An EHL Extension of the Unsteady FBNS Algorithm

2021 ◽  
Author(s):  
Erik Hansen ◽  
Altay Kaçan ◽  
Bettina Frohnapfel ◽  
Andrea Codrignani
Keyword(s):  
Elastic Deformation ◽  
Hydrodynamic Pressure ◽  
Detailed Comparison ◽  
Elastic Deformations ◽  
Surface Textures ◽  
Discretization Schemes ◽  
Grid Points ◽  
Gap Height ◽  
Further Development ◽  
Ball On Disc

Abstract Many engineering applications rely on lubricated gaps where the hydrodynamic pressure distribution is influenced by cavitation phenomena and elastic deformations. To obtain details about the conditions within the lubricated gap, solvers are required that can model cavitation and elastic deformation effects efficiently when a large amount of discretization cells is employed. The presented unsteady EHL-FBNS solver can compute the solution of such large problems that require the consideration of both mass-conserving cavitation and elastic deformation. The execution time of the presented algorithm scales almost with N log(N) where N is the number of computational grid points. A detailed description of the algorithm and the discretized equations is presented. The MATLAB© code is provided in the supplements along with a maintained version on GitHub to encourage its usage and further development. The output of the solver is compared to and validated with simulated and experimental results from the literature to provide a detailed comparison of different discretization schemes of the Couette term in presence of gap height discontinuities. As a final result, the most favourable scheme is identified for the unsteady study of surface textures in ball-on-disc tribometers under severe EHL conditions.

The study of the elastic deformation of a flexible wheel by a cam wave generator

2020 ◽  
Vol 65 (1) ◽  
pp. 51-58
Author(s):  
Sava Ianici
Keyword(s):  
Numerical Simulation ◽  
Finite Element Method ◽  
Finite Element ◽  
Elastic Deformation ◽  
Theoretical Study ◽  
Elastic Field ◽  
The Finite Element Method ◽  
Elastic Deformations ◽  
Wave Generator ◽  
Two Stages

The paper presents the results of research on the study of the elastic deformation of a flexible wheel from a double harmonic transmission, under the action of a cam wave generator. Knowing exactly how the flexible wheel is deformed is important in correctly establishing the geometric parameters of the wheels teeth, allowing a better understanding and appreciation of the specific conditions of harmonic gearings in the two stages of the transmission. The veracity of the results of this theoretical study on the calculation of elastic deformations and displacements of points located on the average fiber of the flexible wheel was subsequently verified and confirmed by numerical simulation of the flexible wheel, in the elastic field, using the finite element method from SolidWorks Simulation.

PVD-Based Microstructuring Surface Techniques for Tribological Applications

2005 ◽  
Author(s):  
A. Alberdi ◽  
M. Marin ◽  
I. Etxeberria ◽  
G. Alberdi
Keyword(s):  
Vapour Deposition ◽  
Mineral Oil ◽  
Tribological Performance ◽  
Physical Vapour Deposition ◽  
Rectangular Grid ◽  
New Techniques ◽  
Surface Textures ◽  
Microstructured Surfaces ◽  
Set Up ◽  
Ball On Disc

Combined techniques of Physical Vapour Deposition (PVD), laser ablation and UV-Photolithography have been set up to produce well defined surface textures able to increase the seizure resistance of high loaded lubricated systems. Using these new techniques, different predefined surface textures, following rectangular grid and zigzag stripped patterns have been generated. The microstructured surfaces developed have been characterised with confocal microscopy, optical and scanning electron microscopy. Ball-on-disc tribological tests under progressively increased load have been carried out using mineral oil as lubricant to determine the influence of surface microtextures on seizure resistance. The influence of shape and size of texture patterns on the tribological performance of the surface have been also studied.

scholarly journals Method to Increase the Accuracy of Large Crankshaft Geometry Measurements Using Counterweights to Minimize Elastic Deformations

2020 ◽  
Vol 10 (14) ◽  
pp. 4722 ◽  
Author(s):  
Leszek Chybowski ◽  
Krzysztof Nozdrzykowski ◽  
Zenon Grządziel ◽  
Andrzej Jakubowski ◽  
Wojciech Przetakiewicz
Keyword(s):  
Elastic Deformation ◽  
Measurement System ◽  
Design Solution ◽  
Structural Elements ◽  
Elastic Deformations ◽  
Elastic Deflection ◽  
Reaction Forces ◽  
Geometry Measurement

Large crankshafts are highly susceptible to flexural deformation that causes them to undergo elastic deformation as they revolve, resulting in incorrect geometric measurements. Additional structural elements (counterweights) are used to stabilize the forces at the supports that fix the shaft during measurements. This article describes the use of temporary counterweights during measurements and presents the specifications of the measurement system and method. The effect of the proposed solution on the elastic deflection of a shaft was simulated with FEA, which showed that the solution provides constant reaction forces and ensures nearly zero deflection at the supported main journals of a shaft during its rotation (during its geometry measurement). The article also presents an example of a design solution for a single counterweight.

ICOs, the next generation of IPOs

2019 ◽  
Vol 46 (6) ◽  
pp. 761-783 ◽  
Author(s):  
Mohammad Hashemi Joo ◽  
Yuka Nishikawa ◽  
Krishnan Dandapani
Keyword(s):  
Initial Public Offering ◽  
Future Development ◽  
Design Methodology ◽  
Detailed Comparison ◽  
Content Type ◽  
Blockchain Technology ◽  
Capital Funding ◽  
The Future ◽  
Public Offering ◽  
Further Development

Purpose The purpose of this paper is to recognize the benefits of the initial coin offering (ICO) as a way of raising funds and to present a detailed comparison between the ICO and the initial public offering to realize the future possibilities that this new funding method holds. Design/methodology/approach It is an exhaustive review of the ICO, the mechanism of crowdfunding, the blockchain technology behind it, benefits and current shortcomings of the ICO, and the potential future development of the ICO as a convenient and efficient way of raising capital. Findings ICOs have brought billions of dollars of funding to startups and projects worldwide in less than two years. Concurrently, many successful ICOs yielded extremely high returns to investors and believers of this new way of funding businesses. Research limitations/implications While the ICO is a revolutionary vehicle for business funding, it has raised concerns among users as well as potential investors about its risk and lack of regulation. The future of this innovative funding method highly depends on further development and placement of appropriate regulatory supervision, better understanding of risk and benefits and attaining the confidence of users. Originality/value This is a review of the advantages and drawbacks of the ICO. If the current fraud, market and cybersecurity risks can be mitigated and standardized regulations are developed, the ICO has a future to become an established way of capital funding or even replace the existing options, regardless of the size and age of companies.

New Deployable Structures Based on an Elastic Origami Model

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
Kazuya Saito ◽  
Akira Tsukahara ◽  
Yoji Okabe
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Simple Model ◽  
Elastic Deformation ◽  
Initial Strain ◽  
New Method ◽  
The Finite Element Method ◽  
Deployable Structures ◽  
Elastic Deformations ◽  
Plate Models

Traditionally, origami-based structures are designed on the premise of “rigid folding,” However, every act of folding and unfolding is accompanied by elastic deformations in real structures. This study focuses on these elastic deformations in order to expand origami into a new method of designing morphing structures. The authors start by proposing a simple model for evaluating elastic deformation in nonrigid origami structures. Next, these methods are applied to deployable plate models. Initial strain is introduced into the elastic parts as actuators for deployment. Finally, by using the finite element method (FEM), it is confirmed that the proposed system can accomplish the complete deployment in 3 × 3 Miura-or model.

Computation of the flow between two rotating coaxial disks: multiplicity of steady-state solutions

1981 ◽  
Vol 108 ◽  
pp. 227-240 ◽  
Author(s):  
M. Holodniok ◽  
M. Kubí[cscr ]ek ◽  
V. Hlavá[cscr ]ek
Keyword(s):  
Reynolds Number ◽  
Steady State ◽  
Detailed Comparison ◽  
Continuation Methods ◽  
Rotating Disks ◽  
Angular Velocities ◽  
Newton Raphson ◽  
Grid Points ◽  
Steady State Solutions ◽  
Number Of Branches

A numerical investigation of the problem of rotating disks is made using the Newton-Raphson and continuation methods. The numerical analysis of the problem was performed for a sequence of values of the Reynolds number R and the ratio of angular velocities of both disks s. It was shown that for higher values of the Reynolds number it is necessary to use a large number of grid points. Continuation of the solution with respect to the parameter s indicated that a number of branches may exist. A detailed discussion for three selected values of s (s = -1, s = 0, s = 1) is presented together with a detailed comparison of our calculations with results already published in the literature.

Hydroelastic Behavior of Air-Supported Flexible Floating Structures

2002 ◽  
Author(s):  
Tomoki Ikoma ◽  
Koichi Masuda ◽  
Hisaaki Maeda ◽  
Chang-Kyu Rheem
Keyword(s):  
Pressure Distribution ◽  
Energy Absorption ◽  
Elastic Deformation ◽  
Wave Energy ◽  
Distribution Method ◽  
Elastic Deformations ◽  
Floating Structures ◽  
Air Chamber ◽  
Air Cushion ◽  
Offshore Field

A pontoon type very large floating structure has elastic deformations in ocean waves. The deformation is larger than that of a semi-submergible type one. Thus, a pontoon type one will be installed to tranquil shallow water field enclosed by breakwaters. Moreover, a semi-submergible one will be applicable to development at offshore field. The authors has developed a pontoon type VLFS with an OWC (oscillating water column) type wave energy absorption system. This can be install to offshore field being deep water relatively. Such VLFS can reduce not only the elastic deformation but also the wave drifting forces. However, it is very difficult to reduce the wave drifting forces effectively because an effect of the reduction depends on the wave energy absorption. Therefore, the authors propose an air supported type VLFS. This idea has been already proposed. However, it wasn’t handled a flexible structure. Such an air-supported structure makes to transmit many waves. Therefore, the wave drifting forces may not increase. In addition, the elastic deformation may decrease because pressure distribution due to the incident waves becomes constant at the bottom of the structure, i.e. the pressure is constant in a same air chamber. We develop the program code for the analysis of the hydrodynamic forces on the VLFS with the air cushion. The potential flow theory is applied and the pressure distribution method is used to the analysis of the wave pressures. The zero-draft is assumed in this method. The pressure and volume change of the air cushion are linearized. In this paper, basic characteristics of the elastic deformations of the air-supported flexible floating structures are investigated. We confirm the effectiveness, and discuss behaviors of the water waves in air chamber areas.

In Situ Observation of Microwedge Effect on Liquid Lubrication

2004 ◽  
Vol 126 (4) ◽  
pp. 690-696 ◽  
Author(s):  
Sy-Wei Lo ◽  
Bo-Qi Zhou ◽  
Ching-Feng Fang ◽  
Yu-Sheng Lu
Keyword(s):  
Elastic Deformation ◽  
Average Velocity ◽  
Contact Region ◽  
Hydrodynamic Pressure ◽  
The Other ◽  
In Situ Observation ◽  
Sliding Velocity ◽  
Surface Separation ◽  
Tool Surface

The influence of the minute elastic deformation of tool surface, named the “microwedge,” on the asperity crushing in liquid lubrication is investigated experimentally. The microwedge plays a role so dominant that although increasing the average velocity of the lubricant can alleviate the asperity deformation; such efforts will be overwhelmed by the microwedge effect if the relative sliding velocity between tool and workpiece is also enhanced concurrently. For all roughness patterns, the asperities show multidirectional expansions of the contact region; an important feature of the microwedge effect. The microwedge effect also creates distributions of surface separation and hydrodynamic pressure neither expected nor explainable by the other models.

Elastohydrodynamic lubrication analysis of metal-on-metal hip prostheses under steady state entraining motion

2001 ◽  
Vol 215 (6) ◽  
pp. 531-541 ◽  
Author(s):  
M Jagatia ◽  
Z M Jin
Keyword(s):  
Film Thickness ◽  
Elastic Deformation ◽  
Hip Prosthesis ◽  
Elastohydrodynamic Lubrication ◽  
Hydrodynamic Pressure ◽  
Acetabular Cup ◽  
Spherical Coordinate ◽  
Hip Prostheses ◽  
General Methodology ◽  
Metal On Metal

The elastohydrodynamic lubrication problem of metal-on-metal hip joint replacements was considered in this study. A simple ball-in-socket configuration was used to represent the hip prosthesis. The Reynolds equation in a spherical coordinate was adopted for the fluid-film lubrication analysis, to account for the ball-in-socket geometry. The corresponding elastic deformation was calculated by means of the finite element method in order to consider the complex ball-in-socket geometry as well as the backing materials underneath the acetabular cup. Both the Reynolds and the elasticity equations were solved simultaneously using the Newton-Raphson finite difference method. The general methodology developed was then applied to a recent experimental prototype metal-on-metal hip implant. It was shown that the backing materials underneath the acetabular cup had little influence on the predicted contact pressure and the elastic deformation at the bearing surfaces for this particular example. Both the film thickness and the hydrodynamic pressure distributions were obtained under various loads up to 2500 N. The predicted minimum lubricating film thickness from the present study was compared with a simple estimation using the Hamrock and Dowson formulae based upon an equivalent ball-on-plane model and excellent agreement was found. However, it was pointed out that for some forms of metal-on-metal hip prostheses with a thin acetabular cup, a polyethylene inlay underneath a metallic bearing insert or a taper connection between a bearing insert and a fixation shell, the general methodology developed in the present study should be used and this will be considered in future studies.

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