The inverse strength problem for evaluation of bending stresses in pipelines during ground movements

2021 ◽  
Vol 87 (9) ◽  
pp. 68-76
Author(s):  
V. M. Markochev
Keyword(s):  
Linear Interpolation ◽  
Design Stage ◽  
Equilibrium Equations ◽  
Ground Movements ◽  
Emergency Situations ◽  
Pipe Section ◽  
Geological Conditions ◽  
Bending Stresses ◽  
Pipeline Route ◽  
Angle Of Rotation

Three variants of the engineering solution of inverse problems regarding the strength of pipeline sections bent as a result of ground movements or during an earthquake are proposed. The feature of this approach consists in calculation of stresses not by the forces acting on the pipe, but by the displacements or deflections. Therefore, full-scale measurements of the detected deviation of the pipe position from the planned pipeline route should be taken as initial data for estimating the values of additional bending stresses. The first problem considered is the assessment of the risk of pipeline malfunction upon sagging or bulging of the supports of aboveground pipelines. The problem is solved in the beam approximation. The pipeline is considered a statically indeterminate beam, one of the supports of which is forcibly moved to a given distance. For a once statically indeterminate beam, a system of four equations — two equilibrium equations and two integral equations for deflections — was solved numerically. The calculated values of three reactions of the supports and the angle of rotation of the pipe section on the first support are used to calculate bending moments, stresses and deflection lines. The problem for a thrice statically indeterminate beam under strain loading was also solved. The second goal is to model the stress-strain state of the pipeline proceeding from the tables of experimental data on the values of pipe deflections and their coordinates. The problem was also solved numerically, using the procedures of smoothing, linear interpolation and sequential differentiation. It is shown that taking into account the possible ambiguous solution of the inverse problem, we should not rely on the calculated values of transverse forces and distributed loads. It is enough to limit ourselves to the second coordinate derivative of the deflection. The third goal is to prevent accidents at the design stage. It is proposed to create a list of normalized deflection functions for modeling possible emergency situations for pipeline sections placed in difficult ground-geological conditions and seismically dangerous zones. The examples of such functions are given.

Evaluation of Design Premises and Uncertainties on the Thermo-Mechanical Behavior of a Subsea Pipeline

2014 ◽  
Author(s):  
Bruno Reis Antunes ◽  
Rafael Familiar Solano ◽  
Alexandre Hansen
Keyword(s):  
Formation Process ◽  
Mechanical Design ◽  
Design Stage ◽  
Stress And Strain ◽  
Lateral Buckling ◽  
Friction Factors ◽  
Global Buckling ◽  
Pipeline Route ◽  
Seabed Bathymetry ◽  
Subsea Pipelines

Buckle formation process is a key subject for the design of subsea pipelines laid on the seabed and operating under high pressure and high temperature (HP/HT) conditions. When the controlled lateral buckling methodology is adopted triggers are placed along pipeline route in order to increase the buckle formation probability in specific locations, sharing pipeline expansion between these sites and reducing the level of stress and strain in each buckle. Despite of its importance, buckle formation process is influenced by several parameters such as the seabed bathymetry, engineered triggers, lateral out-of-straightness (OOS) and pipe-soil interaction. While the first two items above can be defined with reasonable accuracy at previous stages of design, lateral OOS will only be known with tolerable confidence after pipeline installation. The level of uncertainty related to pipe-soil interaction is also considerable since pipeline embedment and friction factors are estimated using equations that include empirical correlations and field collected data. In addition these parameters are influenced by the installation process. Due to these uncertainties, conservative premises are usually assumed in order to obtain a robust pipeline thermo-mechanical design. After pipeline installation and/or start of operation an investigation can be performed in order to confirm the assumptions considered in the design. This paper presents a comparison of premises adopted during design stage of a pipeline based on the controlled lateral buckling methodology and the feedback obtained with the post-lay survey performed. After a brief introduction, pipeline embedment, global buckling at crossings, lateral OOS and sleepers’ height are some of the subjects addressed. Finally, conclusions and recommendations are presented in order to support future similar projects.

scholarly journals Material Origins of Accelerated Operational Wear of RD-33 Engine Blades

2020 ◽  
Author(s):  
Adam Kozakiewicz ◽  
Stanislaw Jóźwiak ◽  
Przemysław Jóźwiak ◽  
Stanisław Kachel
Keyword(s):  
Chemical Composition ◽  
Construction Material ◽  
Operating Conditions ◽  
Design Stage ◽  
Strength Analysis ◽  
Jet Engine ◽  
Emergency Situations ◽  
Low Pressure Turbine ◽  
Propulsion Unit ◽  
Selection Of

The structural and strength analysis of the material used to construct such an important engine element as the turbine is of great significance, both at the design stage as well as during tests and expertises related to emergency situations. Bearing in mind the conditions above mentioned, the paper presents the results of research on the chemical composition, morphology and phased structure of the metallic construction material used to produce the blades of the high and low pressure turbine of the RD-33 jet engine, which is the propulsion unit of the MiG-29 aircraft. The data obtained as a result of the material tests of the blades allowed, on the basis of the analysis of chemical composition and phased structure, to determine the grade of the alloy used to construct the tested elements of the jet engine turbine. The structural stability of the material was found to be lower in comparison with engine operating conditions, which manifested itself as a clear decrease in the resistance properties of the blade material. The results obtained can be used as a basis for analyzing the life span of an object or a selection of material replacements, which enable to produce the analyzed engine element.

scholarly journals Peculiarities of using classification indicators of the coal metamorphism degree for predicting the hazardous coal seams properties

2020 ◽  
Vol 201 ◽  
pp. 01014
Author(s):  
Mykola Antoshchenko ◽  
Elvira Filatieva ◽  
Vladyslav Yefimtsev ◽  
Vadym Tarasov
Keyword(s):  
Spontaneous Combustion ◽  
Chemical Activity ◽  
Mining Engineering ◽  
Coal Seams ◽  
Mining Operations ◽  
Emergency Situations ◽  
Specific Composition ◽  
Geological Conditions ◽  
Definition Of ◽  
Mining Coal

Currently, there is no reliable regulatory framework for determining the hazardous properties of coal seams, including the propensity of coal for spontaneous combustion. Under relatively identical mining engineering and geological conditions for mining coal seams, the probability of emergency situations is determined to a large extent by the genetic properties of coal. The research methodology is based on the classical definition of metamorphism, which characterizes the change in the composition and properties of coal. The analysis involves indicators that directly or indirectly characterize the elemental composition of organic and mineral mass, chemical activity and physico-mechanical properties. This will allow to establish a specific composition and properties that contribute to the manifestation of certain hazardous properties of coal seams during mining operations. It is shown that the modern industrial classification does not take into account the change in the organic and mineral constituents of coal, which does not make it possible to use it unchanged to predict the hazardous properties of coal seams.

scholarly journals Geological Conditions at Preliminary Tunnel Design Stage and Construction Stage: An Evaluation and Assessment.

2000 ◽  
pp. 33-43 ◽  
Author(s):  
Koji NAKAGAWA ◽  
Tetsuharu YASUOKA ◽  
Haruo KITAMURA ◽  
Sigeru MIKI ◽  
Mutsumi FUJIMOTO ◽  
...  
Keyword(s):  
Design Stage ◽  
Construction Stage ◽  
Geological Conditions ◽  
Tunnel Design ◽  
Evaluation And Assessment

Application of rock cover alteration ratio concept in preliminary design of unlined pressure tunnels

2011 ◽  
Vol 48 (11) ◽  
pp. 1674-1682
Author(s):  
André J. Rancourt ◽  
Hani Mitri
Keyword(s):  
Field Measurements ◽  
Shear Zones ◽  
Design Criterion ◽  
Design Stage ◽  
Preliminary Design ◽  
Rock Cover ◽  
Geological Conditions ◽  
Preliminary Design Stage ◽  
Minimum Stress ◽  
Hydraulic Jacking

Unlined pressure tunnels were first driven by the Norwegians into hard granitic rock, which is the ideal material for this type of structure. However, the increase in demand for electric power has propelled the industry to develop projects at sites all over the world with less favourable geological conditions. The paper places emphasis on the preliminary design phase when no field measurements are available. A recent study by Rancourt (published in 2010) has investigated the spatial distribution of the minimum stress that is required to control hydraulic jacking around unlined pressure tunnels. Various surface topographic profiles including slopes, hills, and valleys; the rock cover to tunnel diameter ratio; as well as the presence of geological features such as shear zones and dykes were investigated with numerical modelling. Effective rock cover predictions are compared to those given by the well-known Norwegian design criterion, and a correction factor called cover alteration ratio (CAR) has been introduced. In this paper, a design methodology is proposed for use of CAR at the preliminary design stage in the form of a factor of safety against hydraulic jacking to be used in conjunction with the Norwegian criterion. Limitations on the use of the Norwegian criterion are highlighted.

Advances in the Use of Spaceborne InSAR for Application to Pipeline Route Selection and Integrity Management

2004 ◽  
Author(s):  
Corey R. Froese ◽  
Marco van der Kooij ◽  
Keith Kosar
Keyword(s):  
Ground Subsidence ◽  
Archival Data ◽  
Route Selection ◽  
Movement Rates ◽  
Ground Movements ◽  
Long Time ◽  
Integrity Management ◽  
Pipeline Route ◽  
Time Periods ◽  
Ongoing Monitoring

Spaceborne Synthetic Aperature Radar (InSAR) is a technique that has been used to measure ground movements associated with slope movements and subsidence since the mid-90’s. Previous applications had utilized either dry terrain with no vegetation cover or have relied on the use of articial targets to quanitify deformations. Recent advances in the processing technology have allowed for sub-millimetre level accuracy movements tracking over long time periods and for detection of movements as small as 2 mm/month in vegetated slopes in northern Canada. The archival data and the active aquisitions allow engineers working in the pipeline industry to both review previous movement rates and patterns for planning of pipeline routes and provides a tool for ongoing monitoring of deformations due to ground subsidence or slope movement for operational pipelines.

Toroidal uniformly stressed pressure vessel shell formed by the meridian and ring filament winding

2021 ◽  
Author(s):  
M.A. Komkov
Keyword(s):  
High Pressure ◽  
Cross Section ◽  
Pressure Vessel ◽  
Filament Winding ◽  
Industrial Workers ◽  
Equilibrium Equations ◽  
Emergency Situations ◽  
Breathing Apparatus ◽  
Composite Pressure Vessel ◽  
Toroidal Shells

The paper outlines the prospects for the use of composite toroidal high-pressure cylinders for the breathing apparatus of the Ministry of Emergency Situations, fire brigades, industrial workers, which are more ergonomic in comparison with their cylindrical counterparts. Relying on the analytical solution of the equilibrium equations, we determined the shape of the cross-section of toroidal shells reinforced along the meridians and representing intersecting loop-like curves that form an infinitely long corrugated pipe. The study introduces a solution for a toroidal composite pressure vessel formed by the intersection of the upper and lower branches of the shell, reinforced along the meridians, and a profiled ring layer of filaments installed at the point of their intersection. The parameters of the toroidal uniformly stressed pressure vessel shell made by ring and meridian filament winding are calculated.

The Relevance of Damper Pre-Optimization and its Effectiveness on the Forced Response of Blades

2017 ◽  
Author(s):  
Chiara Gastaldi ◽  
Teresa M. Berruti ◽  
Muzio M. Gola
Keyword(s):  
Turbine Blades ◽  
Time Integration ◽  
Optimization Procedure ◽  
Forced Response ◽  
Contact Forces ◽  
Design Stage ◽  
Geometrical Parameters ◽  
Test Case ◽  
Equilibrium Equations ◽  
Contact Points

The paper presents a calculation procedure for the design of turbine blades with underplatform dampers. The procedure involves damper “pre-optimization” before the coupled calculation with the blades. The pre-optimization procedure excludes, since the early design stage, all those damper configurations leading to low damping performance. Pre-optimization involves plotting a design “damper map” with forbidden areas, corresponding to poorly performing damper geometries and admissible design areas, where effective solutions for the damper shape can be explored. Once the candidate damper configurations have been selected, the damper equilibrium equations are solved by using both the multi-harmonic balance (MHB) method, and the direct time integration method (DTI). Direct time integration of the damper dynamic equations is implemented in order to compute the trend of the contact forces in time and the shape of the hysteresis cycles at the different contact points. Based on these trends, the correct number of Fourier terms to represent the contact forces on the damper is chosen. It is shown that one harmonic term together with the static term, are enough in the MHB calculation of a pre-optimized damper. The proposed method is applied to a test case of a damper coupled with two blades. Experimental forced response functions of the test case with a nominal damper are available for comparison. The purpose of this paper is to show the effectiveness of the “damper maps” in excluding all those damper configurations, leading to undesirable damper behavior and to highlight the strong influence of the blades mode of vibration on the damper effectiveness. From the comparison of dampers with different geometrical parameters, the pre-optimized damper proved to be not only the most effective, in terms of damping capability, but also the one that leads to a faster and more flexible calculation of the damper, coupled with the blades.

Rotating Moderately Thick Annular Disks via an Extension to Classical Theory

2012 ◽  
Vol 28 (2) ◽  
pp. 355-360 ◽  
Author(s):  
A. M. Zenkour
Keyword(s):  
Classical Theory ◽  
Order Theory ◽  
Equilibrium Equations ◽  
Annular Disk ◽  
First Order ◽  
First Order Theory ◽  
Distributed Load ◽  
Vertical Displacements ◽  
Bending Stresses ◽  
Annular Disks

AbstractThe problem of rotating annular disk subjected to a uniformly distributed load is treated in two ways. Stress is divided into a rotating part because of the angular velocity and a bending part due to force loading. New set of equilibrium equations with small deflections is developed. Solutions for radial displacement, deflection, forces and moment resultants, and the rotating and bending stresses of the first-order theory are presented in terms of corresponding quantities of annular disks based on the classical theory. The boundary conditions at the edges of the annular disk are roller supported, clamped or free. Several examples are presented to illustrate the use and accuracy of these relationships. The effects of several parameters on the radial and vertical displacements and rotating and bending stresses are studied. It is observed that the classical theory is sufficient to study the problem of rotating annular disks. However, the inclusion of the effect of shear deformation is necessary to study precisely the curvature of moderately thick annular disks.

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