Reliability-Based Design of Torpedo Anchors

2010 ◽  
Author(s):  
Lui´s Volnei Sudati Sagrilo ◽  
Jose´ Renato Mendes de Sousa ◽  
Edison Castro Prates de Lima ◽  
Elisabeth Campos Porto ◽  
Jane Vieira Volota˜o Fernandes ◽  
...  
Keyword(s):  
Finite Element ◽  
Bearing Capacity ◽  
Prediction Models ◽  
Experimental Tests ◽  
Structural Safety ◽  
Safety Factors ◽  
Reliability Based Design ◽  
Numerical Tools ◽  
Offshore Oil Industry ◽  
Offshore Oil

The use of powerful numerical tools based on the finite element method has been improving the prediction of the ultimate bearing capacity of fixed anchors applied in the offshore oil industry. One of the main achievements of these numerical tools is the reduction of the uncertainty related to the bearing capacity prediction of these anchors. Therefore, it is possible to reduce the design safety factors values that have been calibrated based on prediction models with higher uncertainty, without impairing the original level of the structural safety. This paper presents a reliability-based safety factors calibration study for the design of torpedo anchors considering the statistical model uncertainty evaluated using the results from some experimental tests performed by PETROBRAS and their correspondent finite-element based numerical estimates.

scholarly journals A Study on the Holding Capacity Safety Factors for Torpedo Anchors

2012 ◽  
Vol 2012 ◽  
pp. 1-18 ◽  
Author(s):  
Luís V. S. Sagrilo ◽  
José Renato M. de Sousa ◽  
Edison C. P. Lima ◽  
Elisabeth C. Porto ◽  
Jane V. V. Fernandes
Keyword(s):  
Finite Element ◽  
Experimental Tests ◽  
Structural Safety ◽  
Safety Factors ◽  
Resistance Factors ◽  
Numerical Predictions ◽  
Load And Resistance Factors ◽  
Capacity Calculation ◽  
Offshore Oil Industry ◽  
Offshore Oil

The use of powerful numerical tools based on the finite-element method has been improving the prediction of the holding capacity of fixed anchors employed by the offshore oil industry. One of the main achievements of these tools is the reduction of the uncertainty related to the holding capacity calculation of these anchors. Therefore, it is also possible to reduce the values of the associated design safety factors, which have been calibrated relying on models with higher uncertainty, without impairing the original level of structural safety. This paper presents a study on the calibration of reliability-based safety factors for the design of torpedo anchors considering the statistical model uncertainty evaluated using results from experimental tests and their correspondent finite-element-based numerical predictions. Both working stress design (WSD) and load and resistance factors design (LRFD) design methodologies are investigated. Considering the WSD design methodology, the single safety is considerably lower than the value typically employed in the design of torpedo anchors. Moreover, a LRFD design code format for torpedo anchors is more appropriate since it leads to designs having less-scattered safety levels around the target value.

Finite Element Analysis of Well Pads in Basra Province

2019 ◽  
Vol 7 (1) ◽  
pp. 73-86
Author(s):  
Haider Saad Al-Jubair ◽  
Hiba Abdul Hussein Saheb
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Bearing Capacity ◽  
Contact Pressure ◽  
Cohesionless Soil ◽  
Soil Profiles ◽  
The Finite Element Method ◽  
Safety Factors ◽  
Drilling Rigs ◽  
Element Method

After the year 2003, the oil / gas sector evolved and gained investment. International companies of different origins utilized heavy drilling rigs (to achieve high drilling depths) and entered our region. Meanwhile, some drilling problems were recorded, accompanied by well-pad failure cases. This research aims to study the behavior of well-pads with different geometric configurations, under the effects of drilling rigs with various characteristics, within the Basra province. Four case studies have been selected to represent four fields, namely: Siba, Zubair, West Qurna-2, and Zubair-Mishrif fields. The finite element method is utilized to conduct a stress analysis process, adopting an elastic–plastic constitutive relation for soil, based on Drucker-Prager's yield criterion. The maximum contact pressure applied on soil (under the working loads) is compared to its bearing capacity. When a rigid method is used to calculate the contact pressure, it is compared with the ultimate soil-bearing capacity, as calculated by Reddy and Srinivasan's method for cohesive soils, with allowable bearing capacity taken from the Peck, Hanson, and Thornburn's method for cohesionless soils. The contact pressure calculated via the finite element method is compared with the ultimate soil-bearing capacity calculated using the same method, based on a settlement of 50 mm. The extreme values of the bending moments and shear forces developed in the well-pad sections (under the factored loads), are compared with the section capacities calculated by using the ultimate strength design method. Regarding the geotechnical side, the results indicate insufficient safety factors against soil shear failure for some cases, especially for cohesive soil profiles.  For cohesionless soil profiles, the provided safety factors are sufficient. The finite element method reveals higher contact pressures compared to the conventional rigid method. For cohesionless soil profiles, the Peck, Hanson, and Thornburn's method, gives a bigger safety margin than the finite element method. The immediate settlement values are almost tolerable. Regarding the structural side, it has been identified that a uniform section is adopted for all locations of each pad, for individual wells. In most cases, the provided reinforcing steel is less than the minimum code requirement. This leads to a violation of the section capacity of bending, at least near the cellar. The beam shear capacity is rarely violated. Using strip footings beneath the rig skids, permits utilizing a heavy section that satisfies the requirements of structural safety, without violating the economic considerations.

Design and Research of Double-Drum Winch with Anti-Pressure Wheel

2012 ◽  
Vol 479-481 ◽  
pp. 1709-1713
Author(s):  
Kai An Yu ◽  
Tao Yang ◽  
Chang Zhi Gong
Keyword(s):  
Finite Element ◽  
Bearing Capacity ◽  
Finite Element Methods ◽  
Design Method ◽  
New Method

In view of the problems of large stress and severe bearing heating in double-drum winch at present, this paper adopted a new method to enhance bearing capacity for double-drum winch by adding anti-pressure wheels between two drums. Finite element methods were used to analyze the strength of 4000kN-traction double-drum winches with anti-pressure wheels and without anti-pressure wheels respectively. The results of the analysis revealed that the stress of the cylinder bearing decreased from 264MPa to 167MPa. The new method by adding anti-pressure wheels had remarkably improved the endurance of the bearing. Therefore, the design method can be widely used in large-traction double-drum winch.

scholarly journals Numerical Evaluation of Structural Safety of Linear Actuator for Flap Control of Aircraft Based on Airworthiness Standard

Aerospace ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 104
Author(s):  
Dong-Hyeop Kim ◽  
Young-Cheol Kim ◽  
Sang-Woo Kim
Keyword(s):  
Numerical Analysis ◽  
Analytical Method ◽  
Safety Evaluation ◽  
Experimental Tests ◽  
Structural Safety ◽  
Linear Actuator ◽  
The Finite Element Method ◽  
Margin Of Safety ◽  
Verification Methodology ◽  
The Given

Airworthiness standards of Korea recommend verifying structural safety by experimental tests and analytical methods, owing to the development of analysis technology. In this study, we propose a methodology to verify the structural safety of aircraft components based on airworthiness requirements using an analytical method. The structural safety and fatigue integrity of a linear actuator for flap control of aircraft was evaluated through numerical analysis. The static and fatigue analyses for the given loads obtained from the multibody dynamics analysis were performed using the finite element method. Subsequently, the margin of safety and vulnerable area were acquired and the feasibility of the structural safety evaluation using the analytical method was confirmed. The proposed numerical analysis method in this study can be adopted as an analytical verification methodology for the airworthiness standards of civilian aircraft in Korea.

Influence Coefficient of Filler Plates in Built-Up Cruciform Section Members Formed by Two Equal-Leg Angles

2011 ◽  
Vol 243-249 ◽  
pp. 584-591
Author(s):  
Long Yu Yang ◽  
Zheng Liang Li
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Bearing Capacity ◽  
High Voltage ◽  
Cross Sections ◽  
Radius Of Gyration ◽  
Influence Coefficient ◽  
Transmission Towers ◽  
Minimal Radius ◽  
Extra High Voltage

The built-up cruciform section formed by two equal-leg angles has been widely applied in extra high voltage(EHV) transmission towers, however, domestic codes provide structure requirement and overlook the influence of multi filler plates to members’ bearing capacity. For the purpose of this, a pin end experiment covering 3 different cross sections(Q420, L160*12, L160*14 and L160*16) and 7 different slendernesses(25~55) has been run. This experiment contains totally 21 specimens. Furthermore, large amounts of models have been analysis by finite element method whose parameters contain variety b/t, λ, filler plate intervals and forms, amount of bolts in filler plate. A recommended formula is given for evaluating the influence of filler plates. The results show: multi filler plates enhance bearing capacity slightly for members with λ less than 35, and the better interval for filler plates is 10i-40i(i is the minimal radius of gyration); filler plates do not work well when b/t of the member is extreme large or small, a propositional b/t range for this kind of member is 11-16; the amount of bolts in filler plate has tiny influence on members’ bearing capacity; the recommended formula is applicable and feasible for design.

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