Out-of-Plane Bending (Opb) Test of Large Diameter Mooring Chains

2021 ◽  
Author(s):  
m.r. Karimi ◽  
J. Braun ◽  
E. Gooijer ◽  
P. Barros ◽  
E. Carlberg ◽  
...  
Keyword(s):  
Large Diameter ◽  
Out Of Plane ◽  
Plane Bending

Stress and flexibility factors for multi-mitred pipe bends subjected to internal pressure combined with external loadings

1972 ◽  
Vol 7 (2) ◽  
pp. 97-108 ◽  
Author(s):  
M P Bond ◽  
R Kitching
Keyword(s):  
Internal Pressure ◽  
Large Diameter ◽  
Pipe Bend ◽  
Bending Tests ◽  
Bending Load ◽  
Out Of Plane ◽  
Thin Walled ◽  
Plane Bending ◽  
Internal Pressures ◽  
Stress Patterns

The stress analysis of a multi-mitred pipe bend when subjected to an internal pressure and a simultaneous in-plane or out-of-plane bending load has been developed. Stress patterns and flexibility factors calculated by this analysis are compared with experimental results from a large-diameter, thin-walled, three-weld, 90° multi-mitred bend which was subjected to in-plane bending tests at various internal pressures.

Stress and flexibility factors for multi-mitred bends subjected to out-of-plane bending

1971 ◽  
Vol 6 (4) ◽  
pp. 213-225 ◽  
Author(s):  
M P Bond ◽  
R Kitching
Keyword(s):  
Theoretical Analysis ◽  
Maximum Stress ◽  
Large Diameter ◽  
Stress Distributions ◽  
Factors Associated ◽  
Out Of Plane ◽  
Thin Walled ◽  
Plane Bending ◽  
Stress Ratios

A theoretical analysis has been developed to predict stress distributions and flexibility factors associated with out-of-plane bending of multi-mitred pipe bends. The estimated range of validity of the analysis is sufficient to include most practical multi-mitred pipe bends. Tests on a large-diameter, thin-walled, three-weld right-angled multi-mitred bend were undertaken and the results closely agreed with computations based on the analysis. Predictions for both flexibility factors and overall maximum-stress ratios from the analysis were almost identical with those given by an in-plane bending theory that had been developed from a similar method of approach.

Out-of-Plane Bending (OPB) Test of Large Diameter Mooring Chains

2020 ◽  
Author(s):  
P. Barros ◽  
E. Carlberg ◽  
I. S. Høgsæt ◽  
M. R. Karimi ◽  
J. Braun ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Large Diameter ◽  
Element Model ◽  
Maximum Diameter ◽  
Test Results ◽  
Test Setup ◽  
Out Of Plane ◽  
Plane Bending ◽  
A Chain

Abstract Chevron Corporation and Bluewater Energy Services (BES) performed a chain out-of-plane bending (OPB) test, called OPB MAX hereafter, at DNV GL’s laboratory in Høvik-Norway. The test was performed to study the OPB phenomenon for a chain diameter which was larger than the maximum diameter tested by the OPB JIP. The goal was to understand chain OPB physics for such a large diameter, measure interlink stiffness and maximum sliding moments and validate BES’ in-house finite element model. The current study is a collaboration between all involved parties and the results will be presented in three papers. The first paper summarizes the test setup and instrumentation. The second paper describes the test results, compares them with the OPB JIP estimations and tries to describe the chain OPB physics. The third and the last paper presents the FEA results performed by BES’ in-house finite element model. This paper is the first of the three and focuses on the test setup and instrumentation. The testing machine has been developed by DNV GL and is capable of applying tensions up to 350 t and interlink rotations in the range of ±3 degrees. Two 7-link chain specimens of R4 and R4s grades, both with the nominal diameter of 168 mm were tested at five tension levels from 150, to 350 t. Testing was performed in both wet and dry conditions. Twenty strain gauges were used to measure 3 OPB and 2 IPB moments at 5 mid-link positions. Twelve strain gauge rosettes were used on 3 links to evaluate SCF’s on the OPB hotspots. Seven inclinometers were used to monitor link rotations. DNV GL utilized a digital image processing tool to capture relative movements of chain links and developed a specific data processing tool to calculate the interlink stiffness, perform statistical analysis and provide several levels of data evaluation and comparison between the tests. The paper will provide a description of the test matrix and test objectives are given with the background of the previously performed OPB tests. Next a detailed description of the test rig is presented including the utilized instrumentation. Finally, an explanation of the implemented real-time test monitoring and the performed post-processing on the readings, in line with the test objectives is mentioned. The initial test results are briefly provided at the end.

Out-of-Plane Bending (OPB) Test of Large Diameter Mooring Chains: Test Results

2021 ◽  
Author(s):  
M. R. Karimi ◽  
P. Barros ◽  
E. Carlberg ◽  
P. Vargas
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Large Diameter ◽  
Element Model ◽  
Maximum Diameter ◽  
Test Results ◽  
Out Of Plane ◽  
Dry Conditions ◽  
Plane Bending ◽  
A Chain

Abstract Chevron Corporation and Bluewater Energy Services performed a chain out-of-plane bending (OPB) test campaign, called OPB MAX hereafter, at DNV’s laboratory in Høvik-Norway. The test was performed to study the OPB phenomenon for a chain diameter which was larger than the maximum diameter tested by the OPB JIP [12]. The goal was to understand chain OPB physics for such a large diameter, measure interlink stiffness and maximum sliding moments and validate Bluewater’s in-house finite element model. The current study is a collaboration between all involved parties and the results are presented in three papers. The first paper, Barros et al. [1], summarized the test setup, initial observations and the assumptions used in the post-processing. The current paper describes some of the test results, compares them with the OPB JIP estimations and describes the observed chain OPB physics. The third and the last paper will present the FEA results done by Bluewater’s in-house finite element model. Two seven-link chain specimens of R4 and R4S grades, both with the nominal diameter of 168 mm were tested. Five tension levels of 150, 200, 250, 300 and 350 t were used throughout the tests. Chain sliding was performed in both wet and dry conditions. Twenty strain gauges were attached to five links of each specimen except for the two end-links to measure three OPB and two IPB moments at mid-link. Twelve strain gauge rosettes were used on three links to evaluate SCF on the OPB hotspots. Seven inclinometers were used to monitor link rotations. DNV’s ARAMIS image processing tool was utilized to capture chain movements. A handheld temperature sensor gun monitored the interlink area’s temperature. Interlink stiffness was measured at both ends of each specimen and four intermediate links. Several sensitivity studies were conducted to investigate the effect of loading speed, initial interlink angle and acquisition frequency. The interlink stiffness values that were initially found based on tests at small interlink angles (±0.2 °) were quite consistent and repeatable. Further tests that were performed at large interlink angles (±2.5 °) showed that interlink moment vs. angle hysteresis changes over time and is not unique. This was attributed to deformations observed at the interlink areas that had happened during the tests. The mentioned deformations directly influenced the hysteresis and the associated interlink stiffness values. The nature of deformations and stiffness variations was different during dry and wet tests at large angles. Furthermore, the interlink stiffness values measured on the R4S specimen were quite close to R4 results.

Comparison of Failure Modes of Piping Systems With Wall Thinning Subjected to In-Plane, Out-of-Plane, and Mixed Mode Bending Under Seismic Load: An Experimental Approach

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Izumi Nakamura ◽  
Akihito Otani ◽  
Masaki Shiratori
Keyword(s):  
Dynamic Behavior ◽  
Failure Modes ◽  
Seismic Load ◽  
Piping System ◽  
Shake Table ◽  
Shake Table Tests ◽  
Wall Thinning ◽  
Piping Systems ◽  
Out Of Plane ◽  
Plane Bending

Pressurized piping systems used for an extended period may develop degradations such as wall thinning or cracks due to aging. It is important to estimate the effects of degradation on the dynamic behavior and to ascertain the failure modes and remaining strength of the piping systems with degradation through experiments and analyses to ensure the seismic safety of degraded piping systems under destructive seismic events. In order to investigate the influence of degradation on the dynamic behavior and failure modes of piping systems with local wall thinning, shake table tests using 3D piping system models were conducted. About 50% full circumferential wall thinning at elbows was considered in the test. Three types of models were used in the shake table tests. The difference of the models was the applied bending direction to the thinned-wall elbow. The bending direction considered in the tests was either of the in-plane bending, out-of-plane bending, or mixed bending of the in-plane and out-of-plane. These models were excited under the same input acceleration until failure occurred. Through these tests, the vibration characteristic and failure modes of the piping models with wall thinning under seismic load were obtained. The test results showed that the out-of-plane bending is not significant for a sound elbow, but should be considered for a thinned-wall elbow, because the life of the piping models with wall thinning subjected to out-of-plane bending may reduce significantly.

Stresses in Curved, Circular Thin-Wall Tubes

1963 ◽  
Vol 30 (1) ◽  
pp. 134-135
Author(s):  
E. A. Utecht
Keyword(s):  
Thin Wall ◽  
Bending Moments ◽  
Circular Tubes ◽  
Out Of Plane ◽  
Thin Walled ◽  
Plane Bending

Curves are presented which give stress intensification factors for curved, thin-walled circular tubes under various combinations of in-plane and out-of-plane bending moments.

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