Dynamic Optimization of Steel Catenary Risers Based on Reliability Using Metamodel

2010 ◽  
Author(s):  
Wenqing Zheng ◽  
Hezhen Yang
Keyword(s):  
Dynamic Optimization ◽  
Computational Cost ◽  
Minimum Cost ◽  
Probabilistic Constraints ◽  
Optimization Approach ◽  
Element Analysis ◽  
Steel Catenary Riser ◽  
Reliability Based Design ◽  
Minimum Cost Design ◽  
Steel Catenary Risers

Reliability based design optimization (RBDO) of a steel catenary riser (SCR) using metamodel is investigated. The purpose of the optimization is to find the minimum-cost design subjecting to probabilistic constraints. To reduce the computational cost of the traditional double-loop RBDO, a single-loop RBDO approach is employed. The performance function is approximated by using metamodel to avoid time consuming finite element analysis during the dynamic optimization. The metamodel is constructed though design of experiments (DOE) sampling. In addition, the reliability assessment is carried out by Monte Carlo simulations. The result shows that the RBDO of SCR is a more rational optimization approach compared with traditional deterministic optimization, and using metamodel technique during the dynamic optimization process can significantly decrease the computational expense without sacrificing accuracy.

A Reliability-Based Design Method Using Simulation Techniques and Efficient Optimization Approach

2004 ◽  
Author(s):  
Tong Zou ◽  
Sankaran Mahadevan ◽  
Akhil Sopory
Keyword(s):  
Computational Cost ◽  
Nonlinear Problems ◽  
Side Impact ◽  
System Level ◽  
Optimization Approach ◽  
Sequential Approach ◽  
Model Based ◽  
Reliability Based Design ◽  
Reliability Method ◽  
Simulation Based

A novel reliability-based design optimization (RBDO) method using simulation-based techniques for reliability assessments and efficient optimization approach is presented in this paper. In RBDO, model-based reliability analysis needs to be performed to calculate the probability of not satisfying a reliability constraint and the gradient of this probability with respect to each design variable. Among model-based methods, the most widely used in RBDO is the first-order reliability method (FORM). However, FORM could be inaccurate for nonlinear problems and is not applicable for system reliability problems. This paper develops an efficient optimization methodology to perform RBDO using simulation-based techniques. By combining analytical and simulation-based reliability methods, accurate probability of failure and sensitivity information is obtained. The use of simulation also enables both component and system-level reliabilities to be included in RBDO formulation. Instead of using a traditional RBDO formulation in which optimization and reliability computations are nested, a sequential approach is developed to greatly reduce the computational cost. The efficiency of the proposed RBDO approach is enhanced by using a multi-modal adaptive importance sampling technique for simulation-based reliability assessment; and by treating the inactive reliability constraints properly in optimization. A vehicle side impact problem is used to demonstrate the capabilities of the proposed method.

Analytical Models for Seabed Interaction Effects on Steel Catenary Riser in Touchdown Zone

2013 ◽  
Author(s):  
Kosar Rezazadeh ◽  
Yong Bai ◽  
Jiwei Tang ◽  
Liang Zhang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
System Performance ◽  
Analytical Models ◽  
System Response ◽  
Complex Nature ◽  
Element Analysis ◽  
Steel Catenary Riser ◽  
Steel Catenary Risers ◽  
Seabed Interaction

The complex nature of seabed interaction with steel catenary risers (SCR) in touch down zone (TDZ) of SCRs makes serious difficulties for engineering design industry. Design must ensure that the curvature remains well within elastic limits, and that fatigue damage remains acceptable during the life. Analytical methods, despite it is limited in the accuracy because of idealizations of the system response, it offers a first step in assessing the system performance. The paper compares the results of different seabed interaction models with those from finite element analysis to evaluate the accuracy and consistency of solutions for initial design assumptions and fatigue assessment.

scholarly journals Applying Multiobjective Cost and Weight Optimization to the Initial Design of Turbine Disks

2007 ◽  
Vol 129 (12) ◽  
pp. 1303-1310 ◽  
Author(s):  
A. R. Rao ◽  
J. P. Scanlan ◽  
A. J. Keane
Keyword(s):  
Fatigue Life ◽  
Minimum Weight ◽  
Minimum Cost ◽  
Aircraft Engine ◽  
Integrated System ◽  
Structural Performance ◽  
Manufacturing Cost ◽  
Optimization Approach ◽  
Element Analysis ◽  
Conflicting Objectives

Aerospace design optimization typically explores the effects of structural performance and aerodynamics on the geometry of a component. This paper presents a methodology to incorporate manufacturing cost and fatigue life models within an integrated system to simultaneously trade off the conflicting objectives of minimum weight and manufacturing cost while satisfying constraints placed by structural performance and fatigue. A case study involving the design of a high pressure turbine disk from an aircraft engine is presented. Manufacturing cost and fatigue life models are developed in DECISIONPRO™, a generic modeling tool, whereas finite element analysis is carried out in the Rolls-Royce PLC proprietary solver SC03. A multiobjective optimization approach based on the nondominated sorting genetic algorithm (NSGA) is used to evaluate the Pareto front for minimum cost and volume designs. A sequential workflow of the different models embedded within a scripting environment developed in MATLAB™ is used for automating the entire process.

Reliability Based Design of Femoral Locking Plate Systems

2016 ◽  
Author(s):  
A. Sherif El-Gizawy ◽  
Laurent Eap ◽  
Xuewei Ma
Keyword(s):  
Finite Element ◽  
Locking Plate ◽  
Three Dimensional ◽  
Element Model ◽  
Probabilistic Methods ◽  
Implant Design ◽  
Optimization Approach ◽  
Element Analysis ◽  
Walking Gait ◽  
Reliability Based Design

Reliability based design and optimization approach is developed for femoral locking plate systems. The new approach encompasses finite element analysis, advanced probabilistic analysis, and robust design methodology. A three dimensional finite element model of a locking plate system with a supracondylar femoral fracture will be generated to investigate the device performance. The model will include all physiological loading conditions-hip contact, knee contact, and muscle forces-associated with a normal walking gait cycle. In conjunction with probabilistic methods, Taguchi design optimization will be used to optimize implant design to minimize the probability of failure.

A novel optimization approach for minimum cost design of trusses

2007 ◽  
Vol 85 (23-24) ◽  
pp. 1782-1794 ◽  
Author(s):  
Prakash Kripakaran ◽  
Abhinav Gupta ◽  
John W. Baugh
Keyword(s):  
Minimum Cost ◽  
Optimization Approach ◽  
Minimum Cost Design

A Reliability Index Based Decoupling Method for Reliability-Based Design Optimization

2012 ◽  
Vol 544 ◽  
pp. 223-228 ◽  
Author(s):  
Zhen Zhong Chen ◽  
Hao Bo Qiu ◽  
Hong Yan Hao ◽  
Hua Di Xiong
Keyword(s):  
Design Optimization ◽  
Reliability Index ◽  
Computational Cost ◽  
Probabilistic Constraints ◽  
Reliability Based Design Optimization ◽  
Decoupling Method ◽  
Practical Applications ◽  
Reliability Based Design ◽  
Structure Reliability ◽  
Comparison Results

Reliability-based design optimization (RBDO) evaluates variation of output induced by uncertainties of design variables and results in an optimal design while satisfying the reliability requirements. However, its use in practical applications is hindered by the huge computational cost during the evaluation of structure reliability. In this paper, the reliability index based decoupling method is developed to improve the efficiency of probabilistic optimization. The reliability index is used to calculate the shifting vector in the decoupling process, due to its efficiency in evaluating violated probabilistic constraints. The computation capability of the proposed method is demonstrated using two examples, which are widely used to test RBDO methods. The comparison results show that the proposed method has the same accuracy as the existing methods, and it is also very efficient.

A Moving Morphable Component Based Topology Optimization Approach for Rib-Stiffened Structures Considering Buckling Constraints

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
Weisheng Zhang ◽  
Ying Liu ◽  
Zongliang Du ◽  
Yichao Zhu ◽  
Xu Guo
Keyword(s):  
Topology Optimization ◽  
Degrees Of Freedom ◽  
Computational Cost ◽  
Base Plate ◽  
Optimization Approach ◽  
Element Analysis ◽  
Buckling Constraints ◽  
Design Variables ◽  
Stiffened Structures ◽  
Stiffening Ribs

Stiffened structures are widely used in industry. However, how to optimally distribute the stiffening ribs on a given base plate remains a challenging issue, partially because the topology and geometry of stiffening ribs are often represented in a geometrically implicit way in traditional approaches. This implicit treatment may lead to problems such as high computational cost (caused by the large number of design variables, geometry constraints in optimization, and large degrees-of-freedom (DOF) in finite element analysis (FEA)) and the issue of manufacturability. This paper presents a moving morphable component (MMC)-based approach for topology optimization of rib-stiffened structures, where the topology and the geometry of stiffening ribs are explicitly described. The proposed approach displays several prominent advantages, such as (1) both the numbers of design variables and DOF in FEA are reduced substantially; (2) the proper manufacture-related geometry requirements of stiffening ribs can be readily satisfied without introducing any additional constraint. The effectiveness of the proposed approach is further demonstrated with numerical examples on topology optimization of rib-stiffened structures with buckling constraints.

A Simplified Design Model for Modular Steel Buildings Subject to Vapor Cloud Explosions (VCEs)

2020 ◽  
Vol 14 ◽  
Author(s):  
Osama Bedair
Keyword(s):  
Dynamic Response ◽  
Minimum Cost ◽  
Design Parameters ◽  
Front Wall ◽  
Steel Buildings ◽  
Element Analysis ◽  
Analysis And Design ◽  
Vapor Cloud ◽  
Building Components ◽  
Analytical Expressions

Background: Modular steel buildings (MSB) are extensively used in petrochemical plants and refineries. Limited guidelines are available in the industry for analysis and design of (MSB) subject to accidental vapor cloud explosions (VCEs). Objectives: The paper presents simplified engineering model for modular steel buildings (MSB) subject to accidental vapor cloud explosions (VCEs) that are extensively used in petrochemical plants and refineries. Method: A Single degree of freedom (SDOF) dynamic model is utilized to simulate the dynamic response of primary building components. Analytical expressions are then provided to compute the dynamic load factors (DLF) for critical building elements. Recommended foundation systems are also proposed to install the modular building with minimum cost. Results: Numerical results are presented to illustrate the dynamic response of (MSB) subject to blast loading. It is shown that (DLF)=1.6 is attained at (td/t)=0.4 for front wall (W1) with (td/T)=1.25. For side walls (DLF)=1.41 and is attained at (td/t)=0.6. Conclusions: The paper presented simplified tools for analysis and design of (MSB) subject accidental vapor cloud blast explosions (VCEs). The analytical expressions can be utilized by practitioners to compute the (MSB) response and identify the design parameters. They are simple to use compared to Finite Element Analysis.

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