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Journal ArticleDOI

On the dependence of static flat seal efficiency to surface defects

01 Dec 2011-International Journal of Pressure Vessels and Piping (Elsevier)-Vol. 88, Iss: 11, pp 518-529
TL;DR: In this paper, the role of surface defects on static flat seal efficiency is investigated on synthetic "turned-like" surfaces generated by combinations of the first 50 vibrational eigen modes determined from modal discrete decomposition.
About: This article is published in International Journal of Pressure Vessels and Piping.The article was published on 2011-12-01. It has received 38 citations till now. The article focuses on the topics: Surface roughness.
Citations
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Journal ArticleDOI
TL;DR: In this paper, a model composed of state-of-the-art models for the contact mechanics between rough metal surfaces and for the liquid flow through the rough aperture in-between them was developed.

74 citations

Journal ArticleDOI
TL;DR: In this paper, an original procedure is proposed to systematically analyze and quantify the assembly of parts with form and position defects and deformable contact surfaces. But this procedure is based on the traditional assumption that surfaces have no form defects and are rigid under external loads.
Abstract: Tolerancing activity is usually based on the traditional assumptions that surfaces have no form defects and are rigid under external loads. These assumptions tend to simplify the tolerance analysis of mechanical assemblies and hence the allocation of geometrical specifications. The present paper proposes an original procedure to systematically analyze and quantify the assembly of parts with form and position defects and deformable contact surfaces. Based on this procedure, stochastic simulations are performed by modifying the ratio between the position defects and form defects of surfaces. Even if the form defects are limited, they can lead to a non-compliant assembly. Clearly, the engineer's traditional approach, where form defects are assumed to have no influence, is generally not appropriate if we are to ensure that the expected performance is to be achieved on assembly.

40 citations


Additional excerpts

  • ...5 Geometric parameters [38]...

    [...]

Journal ArticleDOI
Yiping Shao1, Yaxiang Yin1, Shichang Du1, Tangbin Xia1, Lifeng Xi1 
TL;DR: In this article, the authors proposed a series of surface leakage parameters including virtual gasket, contact area percentage (CAP), void volume (VVV), and relative void volume(SW void) as indicators.
Abstract: Leakage directly affects the functional behavior of a product in engineering practice, and surface topography is one of the main factors in static seal to prevent leakage. This paper aims at monitoring the leakage in static sealing interface, using three-dimensional (3D) surface topography as an indicator. The 3D surface is measured by a high definition metrology (HDM) instrument that can generate millions of data points representing the entire surface. The monitoring approach proposes a series of novel surface leakage parameters including virtual gasket, contact area percentage (CAP), void volume (VV), and relative void volume (SWvoid) as indicators. An individual control chart is adopted to monitor the leakage surface of the successive machining process. Meantime, based on the Persson contact mechanics and percolation theory, the threshold of leakage parameter is found using finite element modeling (FEM). Experimental results indicate that the proposed monitoring method is valid to precontrol the machining process and prevent leakage occurring.

24 citations

Dissertation
30 Nov 2011
TL;DR: In this article, the methode OIA (Observation-Interpretation-Agregation) is introduced as an indicateur de compromis entre performance and confiance for a solution de conception.
Abstract: En conception de produits, l'etape de conception dite architecturale doit aboutir a une solution decrivant les caracteristiques du produit, telles que les dimensions ou le choix de composants. Parmi les nombreuses solutions potentielles, il est necessaire d'effectuer un choix et de pouvoir le justifier de maniere rigoureuse. Ce choix doit en outre integrer l'eventuelle presence d'une solution de reference, pouvant par exemple etre issue de projets anterieurs, ou d'etudes preliminaires. Dans ce but, nos travaux presentent une methode d'aide a la decision en vue de selectionner une solution de conception ; nous la nommons methode OIA (Observation-Interpretation-Agregation). Cette methode emploie deux types de modele, l'un pour formaliser le comportement objectif du produit (Observation), l'autre pour les preferences subjectives du concepteur (Interpretation). Dans ces preferences, nous incluons le comportement attendu du produit, la satisfaction du concepteur ainsi que les compromis intrinsequement realises lors du processus de conception. Ces compromis sont realises au travers de strategies de conception et de logiques de ponderations (Agregation). La methode OIA est employee une premiere fois pour qualifier les solutions de conception en termes de performance. Cette methode est ensuite appliquee une seconde fois afin de qualifier la solution par rapport a la solution de reference, en termes de confiance accordee par le concepteur. Nous introduisons la notion d'arc-elasticite en conception comme un indicateur de compromis entre performance et confiance pour une solution de conception. Plusieurs algorithmes stochastiques d'optimisation sont compares comme methodes de recherche de solutions candidates pertinentes. Nous les detaillons, les comparons et proposons une methode de selection multicritere afin d'identifier l'algorithme le plus pertinent. Notre travail est applique au dimensionnement d'une jonction rivetee dans un contexte aeronautique industriel.

17 citations

Journal ArticleDOI
TL;DR: In this article, the second-order slip-corrected Reynolds model is derived, which is shown to be secondorder-accurate in the local slope of the roughness asperities.
Abstract: The slightly compressible flow of a gas in the slip regime within a rough fracture featuring a heterogeneous aperture field is analysed in depth in this work. Starting from the governing Navier–Stokes, continuity and gas state law equations together with a first-order slip boundary condition at the impermeable walls of the fracture, the two-dimensional slip-corrected Reynolds model is first derived, which is shown to be second-order-accurate in the local slope of the roughness asperities while being first-order-accurate in the Knudsen number. Focusing the interest on the flow-rate to pressure-gradient relationship over a representative element of the fracture, an upscaling procedure is applied to the local Reynolds equation using the method of volume averaging, providing a macroscopic model for which the momentum conservation equation has a Reynolds-like form. The effective macroscopic transmissivity tensor, which is characteristic of the representative element, is shown to be given by a closure problem that is non-intrinsic to the geometrical structure of the fracture only due to the slip effect. An expansion to the first order in the Knudsen number is carried out on the closure, yielding a decomposition of the effective transmissivity tensor into its purely viscous part and its slip correction, both being given by the solution of intrinsic closure subproblems. Numerical validations of the solution to the closure problem are performed with analytical predictions for simple fracture geometries. Comparison between the macroscopic transmissivity tensor, obtained from the solution of the closure problem, and its first-order approximation is illustrated on a randomly rough correlated Gaussian fracture.

16 citations

References
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Book
01 Jan 1966
TL;DR: In this article, the Straight Line Case is used to fit a straight line by least squares, and the Durbin-Watson Test is used for checking the straight line fit.
Abstract: Basic Prerequisite Knowledge. Fitting a Straight Line by Least Squares. Checking the Straight Line Fit. Fitting Straight Lines: Special Topics. Regression in Matrix Terms: Straight Line Case. The General Regression Situation. Extra Sums of Squares and Tests for Several Parameters Being Zero. Serial Correlation in the Residuals and the Durbin--Watson Test. More of Checking Fitted Models. Multiple Regression: Special Topics. Bias in Regression Estimates, and Expected Values of Mean Squares and Sums of Squares. On Worthwhile Regressions, Big F's, and R 2 . Models Containing Functions of the Predictors, Including Polynomial Models. Transformation of the Response Variable. "Dummy" Variables. Selecting the "Best" Regression Equation. Ill--Conditioning in Regression Data. Ridge Regression. Generalized Linear Models (GLIM). Mixture Ingredients as Predictor Variables. The Geometry of Least Squares. More Geometry of Least Squares. Orthogonal Polynomials and Summary Data. Multiple Regression Applied to Analysis of Variance Problems. An Introduction to Nonlinear Estimation. Robust Regression. Resampling Procedures (Bootstrapping). Bibliography. True/False Questions. Answers to Exercises. Tables. Indexes.

18,952 citations

Journal ArticleDOI
TL;DR: In this article, the authors proposed a new theory of elastic contact, which is more closely related to real surfaces than earlier theories, and showed how the contact deformation depends on the topography of the surface, and established the criterion for distinguishing surfaces which touch elastically from those which touch plastically.
Abstract: It is usually assumed that the real area of contact between two nominally flat metal surfaces is determined by the plastic deformation of their highest asperities. This leads at once to the result that the real area of contact is directlyproportional to the load and independent of the apparent area-a result with many applications in the theories of electric contacts and friction. Archard pointed out that plastic deformation could not be the universal rule, and introduced a model which showed that, contrary to earlier ideas, the area of contact could be proportional to the load even with purely elastic contact. This paper describes a new theory of elastic contact, which is more closely related to real surfaces than earlier theories. We show how the contact deformation depends on the topography of the surface, and establish the criterion for distinguishing surfaces which touch elastically from those which touch plastically. The theory also indicates the existence of an 'elastic contact hardness', a composite quantity depending on the elastic properties and the topography, which plays the same role in elastic contact as the conventional hardness does in plastic contact. A new instrument for measuring surface topography has been built; with it the various parameters shown by the theory to govern surface contact can be measured experimentally. The typical radii of surface asperities have been measured. They were found, surprisingly, to be orders of magnitude larger than the heights of the asperities. More generally we have been able to study the distributions of asperity heights and of other surface features for a variety of surfaces prepared by standard techniques. Using these data we find that contact between surfaces is frequently plastic, as usually assumed, but that surfaces which touch elastically are by no means uncommon in engineering practice.

5,371 citations

Book
01 Jan 1978

5,151 citations

Journal ArticleDOI
TL;DR: In this paper, a class of incomplete three level factorial designs useful for estimating the coefficients in a second degree graduating polynomial are described and the designs either meet, or approximately meet, the criterion of rotatability and for the most part can be orthogonally blocked.
Abstract: A class of incomplete three level factorial designs useful for estimating the coefficients in a second degree graduating polynomial are described. The designs either meet, or approximately meet, the criterion of rotatability and for the most part can be orthogonally blocked. A fully worked example is included.

3,194 citations