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Determining the tightening load of bolted flange assemblies is essential to ensure both joint tightness and the mechanical strength of the components. Classical calculation methods generally evaluate sealing and strength conditions separately and do not always provide a global view of the admissible tightening range. The TBSS method (Tight Between Seal and Strength) proposes an integrated approach in which these conditions are expressed as equivalent tightening loads. This formulation makes it possible to define two tightening limits framing the operational tightening load. This article is the third and final part of a series devoted to bolted flange connections.
The design of bolted flange connections requires ensuring both leak tightness and the mechanical resistance of their components. Design codes generally define flanges, gaskets and bolting through pressure classes or standardized dimensions, without directly providing the tightening force to be applied. This article presents the mechanical framework used to analyze such assemblies: calculation assumptions, flange modelling based on the Taylor Forge method, effective gasket area, bolt preload and the loadings to be considered. It also introduces the resistance criteria applicable to flanges, gaskets and bolts. This article is the second part of a three-article series devoted to bolted flange assemblies.
Bolted flange connections are widely used in industrial installations handling pressurized fluids, particularly in the nuclear, petrochemical, offshore drilling and naval industries. Their function is to ensure both the structural continuity of the circuit and the sealing of the pressure boundary. The reliability of these assemblies relies on the interaction between three main components: the flanges, the gasket and the bolting. This article presents the main characteristics of these components, their respective functions, and the principles ensuring their compatibility in the design of leak-tight joints. It also introduces the tightening control approach and the TBSS method (Tight Between Seal and Strength). It is a first part of a series devoted to bolted flange connections.
This article deals with the issue of the dimensioning of thin plane parts. It focuses on the case of shear and bearing stress under static loading up to rupture. These structures are characterized by the fact that they are generally composed of several rows of bolts and that the resistance of the assembly is not determined by that of the most loaded bolt but by that of each assembled part. This article presents the behavior of such assemblies under static stress and notably deals with the complex problem of calculating the load-distribution on the various fastening rows of a fish-plating.
The first airplanes had no brakes. They didn't need them; their weight and take-off speed were low enough. Then, as engines became more powerful, planes got bigger and faster. Their wheels were then fitted with brakes extrapolated from those used on automobiles, i.e. drum brakes with independent control for each side, which also enabled them to take turns at low speed. The propellers of piston engines, or even later turboprop engines, were equipped with variable pitch and even pitch reversal, making them easy to slow down. With jet engines, brakes became critical, as they were virtually the only truly effective means of slowing down.
What is sealing? Tightness is the quality of a closed enclosure that does not allow any fluid to pass through its walls. Obtaining and maintaining such a property is, in reality, a gradation of operations, and the hermeticity of an enclosure must be considered, even from a theoretical point of view, as illusory. A perfectly homogeneous structure can be permeated by gases, due to sorption and desorption at the solid's interfaces, and solution and diffusion within it. This complex process, known as permeation, varies greatly according to the nature of the elements involved. Gas permeation through metals, for example, is not usually likely to affect sealing, whereas gas permeation through elastomers can lead to ambiguities in leak detection.
The welding of metal materials for assembly can result in modification of the isostatic lines and the local mechanical behavior of the material through the ties made.This article specifies the methodologies applicable to the calculation of assemblies subjected to variable loading, and the verification of the harmfulness of the defects outside the usual manufacturing tolerances. This presentation, which particularly concerns steels and aluminum alloys, and which makes extensive use of normative documents from the field of construction, endeavors to be complete, explanatory and up-to-date.
The aim of this article is to explain the behavior of axially loaded screw joints. A prestressed joint subjected to an external stress carried by the bolt axis is provided: prestressing, loading the joint and joining. Following, the determination of stiffness is presented, such as the distribution of constraints, the axial stiffness of the bolt or the stiffness of the assembled parts. Thermal stresses are then addressed: general expression, specific case, calculation of constraints, and so forth. The article concludes with discussions concerning the distance between two successive bolts or screws.
The modeling of laminated composite structures can appear complex due to the heterogeneity and anisotropy of these materials, as well as the wide variety of stacking sequence combinations. Classical laminate theory provides a convenient and insightful representation of composite behavior, from the ply to the full laminate, but it is insufficient for designing complex structures. This article presents the behavior of the elementary ply, methodologies adapted to composite structures, and advanced optimization approaches, illustrated through three application cases using finite element modeling.
Mechatronics isa domain at the interface of mechanics, electronics and computation. This synergy action aims at improving the functionalities of a product. Mechatronic devises are used in order to pilot systems and retroact in order to adapt to the varying conditions of functioning. This article presents the integration process of the various domains (mechanical, control, electronic, software) as well as the components used in order to optimize a product. Mechatronics has gradually spread in many industrial sectors as presented in this paper. The prospects for mechatronic systems applications are immense.
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