The Stress Analysis and Experimental Research of Tubular K-Joints With Overlap

1987 ◽  
Vol 109 (4) ◽  
pp. 375-380
Author(s):  
Tie-yun Chen ◽  
Wei-min Chen

The geometry of overlapping tubular joints, the equations of intersection curves and the coordinate of the intersection point are introduced first. The variational method for simple tubular joints is extended to the stress analysis of tubular K-joints with overlap. The computer program is compiled. The stress concentration factor and the position of the hot spot of an overlapping joint are found. For the sake of proving the feasibility of our analysis and program, the computed results are compared with experimental data of our photoelastic experiment and other experiments.

1984 ◽  
Vol 106 (1) ◽  
pp. 43-45
Author(s):  
T. Y. Chen ◽  
B. Z. Chen ◽  
Y. Q. Wang

An analytical method for the stress analysis of tubular joints of T, Y, K type is presented in this paper. The stress distribution and stress concentration factor of the joints are calculated. Numerical results are in good agreement with the experimental results.


Author(s):  
Nathalia Paruolo ◽  
Thalita Mello ◽  
Paula Teixeira ◽  
Marco Pérez

Abstract In the oil and gas industry, fixed platforms are commonly applied in shallow water production. In-place environmental conditions generates cyclic loads on the structure that might lead to structural degradation due to fatigue damage. Fatigue is one of the most common failure modes of offshore structures and is typically estimated when dimensioning of the structure during design phase. However, in times when life extension of existing offshore structures is being a topic in high demand by industry, mature fields may represent an interesting investment, especially for small companies. Concerning fixed platforms, composed mainly by welded tubular joints, the assessment of hot spot stresses is considered to predict structure fatigue. The estimation of welded joint hot spot stresses is based on the stress concentration factors (SCFs), which are given by parametric formulae, finite element analysis (FEA) or experimental tests. Parametric formulae may be defined as a fast and low-cost method, meanwhile finite elements analysis may be time consuming and experimental tests associated with higher costs. Given these different characteristics, each method is applied according to the study case, which will rely on the joint geometry and associated loads. Considering simple joint geometries several sets of parametric equations found in the literature may be applied. On the other hand, the SCFs calculation of non-studied yet complex joints consider known formulae adapted according to the under load joint behavior and geometry. Previous analysis shows that this adaptation may furnish different results compared to those obtained by FEA. Furthermore, it is observed that even for simple joints the results derived from the different methods may differ. Given their importance for the oil and gas industry, since they are the basis for the assessment of the fatigue life of welded tubular joints which may impact on additional costs related to maintenance and inspection campaigns, the estimation of SCFs must be the most accurate as possible. Therefore, this paper intends to investigate the differences between results derived from parametric formulae and different FEA studies.


Author(s):  
Kris Hectors ◽  
Hasan Saeed ◽  
Wim De Waele

Abstract A new fatigue lifetime assessment approach for offshore jacket structures is presented. It combines a previously developed numerical framework for automated determination of stress concentration factors in tubular joints and a multidimensional finite element modelling approach. The approach is explained based on a case study of an OC4 type offshore jacket. To determine the fatigue life, a directional wave spectrum is combined with the JONSWAP spectrum. The fatigue life of the jacket is assessed for two different sea states. Based on the fatigue analysis the most fatigue critical wave direction is identified. The hot spot stresses in one of the most critical joints are determined and compared to stresses obtained with the Efthymiou equations. The shortcomings of these equations are highlighted and it is shown how the numerical framework can be used to improve the current fatigue design philosophy for offshore jackets which relies on the Efthymiou equations for stress concentration factors in the welded tubular joints.


Author(s):  
R. M. Andrews ◽  
S. Wheat ◽  
M. Brown ◽  
C. Fowler

Parametric formulae derived for offshore structural tubular joints have been assessed for potential use for estimating stress intensification factors for pipe stress analysis. The background to these equations is given and comparisons made for a range of typical geometries. Despite the absence of a “plug” of material in a pipe joint, the tubular joint equations appear suitable for the estimation of stress intensification factors for fabricated tees subjected to moment loading of the branch. It is considered that this approach should be investigated further by code developers.


1985 ◽  
Vol 107 (4) ◽  
pp. 473-478
Author(s):  
T.-Y. Chen ◽  
B.-Z. Chen ◽  
Y.-Q. Wang

The relationship between the geometric parameters of α, β, γ and τ of tubular T joints and chord stress concentration factor, SCF, has been investigated. With the use of calculated values as well as experimental data tables were compiled for a wide variety of cases when axial loading on the branch is applied. Finally, a probability analysis is given as to the reliability of using a particular SCF value.


1985 ◽  
Vol 107 (1) ◽  
pp. 60-67
Author(s):  
S. Dharmavasan ◽  
W. D. Dover

The available data on hot spot stress for tubular welded joints has been reviewed and a database established. Stress analysis techniques in general use for the design of offshore structures and parametric equations have been assessed against this database to determine their accuracy. A set of equations to predict the stress distributions for simple joints has been proposed and has been used to predict mixed mode stress concentration factors. Results obtained from a complex K joint have been examined in detail and the importance of the stress state, when predicting the mixed mode stress concentration factors, is demonstrated.


2019 ◽  
Vol 286 ◽  
pp. 02004
Author(s):  
E. Chouha ◽  
S.E. Jalal ◽  
Z. El Maskaoui ◽  
A. Chouaf

The welded tubular joints can be used in several industrial fields including, metallic bridges, telecommunication tripods, oil platforms and pipelines. These structures can be damaged by concentrated stresses located in the toe weld vicinity. Semi-parametric formulas, currently available in the literature, can be used to predict the value of the stress concentration factor without given the hot spot location. In this work, a Finite Elements modeling was carried out for a T-joint, in order to have the concentrated stress value around the weld toe. This work was investigated for a series of combined loads.


2020 ◽  
Vol 213 ◽  
pp. 03014
Author(s):  
Kai Zhou ◽  
Jingjing Zuo ◽  
Wenhua Wang ◽  
Shiliu Bao

The support structure for an offshore wind turbine is subjected to combined hydrodynamic loads and aerodynamic loads. The tubular joints are the weakest component leading to fatigue failure of the whole structure. Based on the multi-pile foundation structure which is used widely in China, the typical threeplanar tubular Y-joints is selected to study stress concentration factor (SCF). Then, the load types subjected to axial loadings of three-planar tubular Y-joints are determined. The finite element models of three-planar tubular Y-joints are established and used to calculate hot spot stresses. The stress concentration factors along the weld of the three-planar tubular Y-joints under the axial forces are obtained. The effects of geometrical parameters on SCFs are studied.


Author(s):  
Ivelin Kostov

In the work brought some experimental data of kinematic parameters of movement of cars forced idle, as the software product was used to diagnose 900 ATS, which recorded kinematic parameters of vehicle. On the basis of the conducted experimental research results are shown tabulated and analysed.


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