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.

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.

Characterization of the Dynamical Response of a Micromachined G-Sensor to Mechanical Shock Loading

2007 ◽  
Author(s):  
Daniel E. Jordy ◽  
Mohammad I. Younis
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Squeeze Film ◽  
Dynamical Response ◽  
Mems Devices ◽  
Damping Coefficients ◽  
Squeeze Film Damping ◽  
Out Of Plane ◽  
Gap Width

Squeeze film damping has a significant effect on the dynamic response of MEMS devices that employ perforated microstructures with large planar areas and small gap widths separating them from the substrate. Perforations can alter the effect of squeeze film damping by allowing the gas underneath the device to easily escape, thereby lowering the damping. By decreasing the size of the holes, the damping increases and the squeeze film damping effect increases. This can be used to minimize the out-of-plane motion of the microstructures toward the substrate, thereby minimizing the possibility of contact and stiction. This paper aims to explore the use of the squeeze-film damping phenomenon as a way to mitigate shock and minimize the possibility of stiction and failure in this class of MEMS devices. As a case study, we consider a G-sensor, which is a sort of a threshold accelerometer, employed in an arming and fusing chip. We study the effect of changing the size of the perforation holes and the gap width separating the microstructure from the substrate. We use a multi-physics finite-element model built using the software ANSYS. First, a modal analysis is conducted to calculate the out-of-plane natural frequency of the G-sensor. Then, a squeeze-film damping finite-element model, for both the air underneath the structure and the flow of the air through the perforations, is developed and utilized to estimate the damping coefficients for several hole sizes. Results are shown for various models of squeeze-film damping assuming no holes, large holes, and assuming a finite pressure drop across the holes, which is the most accurate way of modeling. The extracted damping coefficients are then used in a transient structural-shock analysis. Finally, the transient shock analysis is used to determine the shock loads that induce contacts between the G-sensor and the underlying substrate. It is found that the threshold of shock to contact the substrate has increased significantly when decreasing the holes size or the gap width, which is very promising to help mitigate stiction in this class of devices, thereby improving their reliability.

Forming limit diagrams by including the M–K model in finite element simulation considering the effect of bending

2016 ◽  
Vol 232 (8) ◽  
pp. 625-636 ◽  
Author(s):  
Mostafa Habibi ◽  
Ramin Hashemi ◽  
Ahmad Ghazanfari ◽  
Reza Naghdabadi ◽  
Ahmad Assempour
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Metal Forming ◽  
Forming Limit Diagram ◽  
Element Model ◽  
Forming Limit ◽  
Finite Element Models ◽  
Element Simulation ◽  
Simple Tension ◽  
Out Of Plane

Forming limit diagram is often used as a criterion to predict necking initiation in sheet metal forming processes. In this study, the forming limit diagram was obtained through the inclusion of the Marciniak–Kaczynski model in the Nakazima out-of-plane test finite element model and also a flat model. The effect of bending on the forming limit diagram was investigated numerically and experimentally. Data required for this simulation were determined through a simple tension test in three directions. After comparing the results of the flat and Nakazima finite element models with the experimental results, the forming limit diagram computed by the Nakazima finite element model was more convenient with less than 10% at the lower level of the experimental forming limit diagram.

Tension and shear block failure of bolted gusset plates

2006 ◽  
Vol 33 (4) ◽  
pp. 395-408 ◽  
Author(s):  
Bino B.S Huns ◽  
Gilbert Y Grondin ◽  
Robert G Driver
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Test Results ◽  
Limit States ◽  
Gusset Plates ◽  
Gusset Plate ◽  
Current Design ◽  
Shear Block ◽  
The Finite Element Model

Despite the large database of test results for tension and shear block failure in gusset plates, the exact progression of the failure mechanism is not clear. Although current design equations predict the capacity of gusset plates fairly well, it is important for a design equation to not only predict the capacity reliably but also reflect the failure mode accurately. Recent experimental and numerical research has indicated that current design equations do not always predict the failure behaviour accurately. A finite element model was therefore developed to predict the sequence of events that leads to the tear-out of a block of material from a bolted gusset plate in tension. The model was developed to provide a useful tool for studying tension and shear block failure in gusset plates and other structural elements. This paper presents the development of the finite element model and procedure for prediction of tension and shear block failure in gusset plates. Making use of the finite element model, the database of test results is also expanded to include gusset plates with a larger number of transverse lines of bolts than what has been obtained experimentally. A reliability analysis is used to assess several design equations, including the equation adopted in CAN/CSA-S16-01 and a unified equation proposed recently for several types of bolted connections. From this work, a limit states design equation is proposed for gusset plates.Key words: gusset plate, limit states design, reliability, shear rupture, tension rupture, finite element analysis, failure criterion.

scholarly journals Performance of low rise concealed truss composite shear walls with external columns

2018 ◽  
Vol 38 (2) ◽  
pp. 131-142
Author(s):  
Dan Zhang ◽  
Zhong Tao ◽  
Lei Zhang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Experimental Studies ◽  
Shear Walls ◽  
Element Model ◽  
Monotonic Loading ◽  
Test Results ◽  
Flat Steel ◽  
Composite Shear ◽  
Constant Axial Load

A review on the previous studies shows that limited analytical or experimental studies on the low-rise concealed truss shear walls with external columns under monotonic loading have already been conducted. The combination of concealed truss was welded to I-shaped steel frame and flat steel support. Two different aspect ratio composite shear walls were tested under static monotonic loading, and the failure mode, bearing capacity, ductility and stiffness were explored. A finite element model was developed and used to simulate the composite shear walls under constant axial load and lateral loading. The comparison of test results confirmed that the finite element model could predict the behavior of composite shear walls accurately. Meanwhile, stress analyses of the specimens were studied to simulate stress distribution of reinforcement, and to analyze the steel of composite shear wall with external columns at different loading stages. Taken together, this study could be a basis for developing an accurately simplified model.

Riveted Hull Joint Design in RMS Titanic and Other Pre—World War I Ships

2003 ◽  
Vol 40 (02) ◽  
pp. 82-92
Author(s):  
Richard Woytowich
Keyword(s):  
Finite Element ◽  
World War I ◽  
Finite Element Model ◽  
Plate Thickness ◽  
Element Model ◽  
World War ◽  
Joint Construction ◽  
Riveted Joints ◽  
Riveted Joint ◽  
Out Of Plane

Beginning with an overview of riveted joint construction, this paper shows that the efficiency of riveted joints in pre-World War I ships decreased as plate thickness increased. In the case of the RMS Titanic, some of the joints involved in the iceberg impact were only about 27% as strong as the plates they connected. A finite element model is used to show how such a joint would respond to the sort of out-of-plane load that the iceberg would have applied. For one possible load configuration, the joint failure is recreated. Finally, although Titanic and her sisters were not built to class, the design of the riveted joints is examined in the context of relevant Lloyd's Register of Shipping Rules.

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