Numerical Modelling of Floating Breakwaters and Shape Optimization Using a Nonlinear Programming Method

2007 ◽  
Author(s):  
Ghassan Elchahal ◽  
Rafic Younes ◽  
Pascal Lafon
Keyword(s):  
Shape Optimization ◽  
Information Technologies ◽  
Optimization Procedure ◽  
Sqp Method ◽  
Mechanical Constraints ◽  
Mathematical Expressions ◽  
Numerical Tools ◽  
Floating Breakwaters ◽  
Geometrical Dimensions ◽  
Nonlinear Programming Method

In this paper, shape optimization is addressed through sequential quadratic programming (SQP). The recent increase in information technologies dedicated to optimal design, associated with the progress of the numerical tools, allows significant improvement in the design optimization of floating breakwaters. First of all, the physical and mechanical constraints, related to the environment of floating breakwaters, are expressed in terms of the geometrical dimensions of the latter in form of mathematical expressions. Then, the optimization procedure is developed based on SQP method and satisfactory results are obtained demonstrating the capability of this work.

Structural Shape Optimization Wth Error Control

1994 ◽  
Author(s):  
Pierre Duysinx ◽  
WeiHong Zhang ◽  
HaiGuang Zhong ◽  
Pierre Beckers ◽  
Claude Fleury
Keyword(s):  
Shape Optimization ◽  
Computer Aided Design ◽  
Adaptive Mesh Refinement ◽  
Error Control ◽  
Optimization Procedure ◽  
Adaptive Mesh ◽  
Structural Shape ◽  
Structural Shape Optimization ◽  
Design Variables ◽  
Recent Developments

Abstract A robust and automatic shape optimization procedure is presented in this paper, which incorporates recent developments in the field of computer-aided design (CAD) of mechanical structures, such as geometric modelling, automatic selection of independent design variables, sensitivity analysis using reliable mesh perturbation schemes, error estimation and adaptive mesh refinement. A numerical example is given to show the efficiency of the procedure.

Robust Shape Optimization of Uncertain Dense Gas Flows Through a Plane Turbine Cascade

2011 ◽  
Author(s):  
Samuel J. Hercus ◽  
Paola Cinnella
Keyword(s):  
Robust Optimization ◽  
Shape Optimization ◽  
Flow Behavior ◽  
Computational Cost ◽  
Optimization Procedure ◽  
System Stability ◽  
Dense Gas ◽  
Turbine Cascade ◽  
The Mean ◽  
Inlet Conditions

A robust shape optimization procedure based on a multi-objective genetic algorithm coupled to a non-intrusive uncertainty quantification analysis was applied to a transonic inviscid flow of a dense gas over a plane turbine cascade. The goal was to simultaneously improve the mean turbine performance and the system stability under fluctuating thermodynamic inlet conditions. Despite an elevated computational cost, the optimization procedure was capable of generating a Pareto front of turbine geometries which improved the mean isentropic turbine efficiency μ(ηs) over the baseline profile, while limiting the solution variability in terms of the coefficient of variation of the power output CV(P2D). In addition to demonstrating an excellent parallel scalability over 1600 processors, the robust optimization revealed that variability of CV(P2D) depends more on the variation of inlet conditions than turbine geometry. A posteriori stochastic analyses on selected optimized turbine geometries allowed an investigation of flow behavior variability, as well as propositions for the improved selection of robust optimization cost criteria in future simulations.

An Energy Formulation for Parametric Size and Shape Optimization of Compliant Mechanisms

1999 ◽  
Vol 121 (2) ◽  
pp. 229-234 ◽  
Author(s):  
J. A. Hetrick ◽  
S. Kota
Keyword(s):  
Shape Optimization ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Optimization Procedure ◽  
Stress Constraints ◽  
Optimization Techniques ◽  
Mechanical Transmission ◽  
Dimensional Synthesis ◽  
Size And Shape ◽  
Mechanical Devices

Compliant mechanisms are jointless mechanical devices that take advantage of elastic deformation to achieve a force or motion transformation. An important step toward automated design of compliant mechanisms has been the development of topology optimization techniques. The next logical step is to incorporate size and shape optimization to perform dimensional synthesis of the mechanism while simultaneously considering practical design specifications such as kinematic and stress constraints. An improved objective formulation based on maximizing the energy throughput of a linear static compliant mechanism is developed considering specific force and displacement operational requirements. Parametric finite element beam models are used to perform the size and shape optimization. This technique allows stress constraints to limit the maximum stress in the mechanism. In addition, constraints which restrict the kinematics of the mechanism are successfully applied to the optimization problem. Resulting optimized mechanisms exhibit efficient mechanical transmission and meet kinematic and stress requirements. Several examples are given to demonstrate the effectiveness of the optimization procedure.

scholarly journals A shape optimization procedure for cylinders aeolian tone

2019 ◽  
Vol 182 ◽  
pp. 37-51 ◽  
Author(s):  
Wagner José Gonçalves da Silva Pinto ◽  
Florent Margnat
Keyword(s):  
Shape Optimization ◽  
Optimization Procedure

Size and Shape Optimization of Compliant Mechanisms: An Efficiency Formulation

1998 ◽  
Author(s):  
Joel A. Hetrick ◽  
Sridhar Kota
Keyword(s):  
Shape Optimization ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Optimization Procedure ◽  
Stress Constraints ◽  
Mechanical Efficiency ◽  
Optimization Techniques ◽  
Mechanical Transmission ◽  
Dimensional Synthesis ◽  
Size And Shape

Abstract Compliant mechanisms are jointless mechanical devices that take advantage of elastic deformation to achieve a force or motion transformation. A milestone toward systematic design of compliant mechanisms has been the development of topology optimization techniques. The next logical step is to incorporate size and shape optimization to identify the exact dimensional form of the mechanism. A new objective formulation based on maximizing the mechanical efficiency of a compliant mechanism is developed in order to perform the size and shape optimization. An advantage of this formulation is that precise control over the mechanism’s mechanical or geometric advantage can be enforced during optimization. Finite element beam models are used to perform dimensional synthesis of planar compliant mechanisms. This technique allows stress constraints to limit the maximum stress in the mechanism which improves the mechanism’s durability and flexibility. Resulting optimized mechanisms exhibit efficient mechanical transmission and meet kinematic and stress requirements. Several examples are given to demonstrate the effectiveness of the optimization procedure.

Multiple Objective Preform Die Shape Optimization Design for Controlling Forging’s Shape and Deforming Force during Forging Process

2011 ◽  
Vol 306-307 ◽  
pp. 1504-1507 ◽  
Author(s):  
Xin Hai Zhao ◽  
Guo Qun Zhao ◽  
Xiao Hui Huang ◽  
Yi Guo Luan
Keyword(s):  
Shape Optimization ◽  
Objective Function ◽  
Optimization Design ◽  
Control Point ◽  
Optimization Procedure ◽  
Multiple Objective ◽  
Forging Process ◽  
Weighted Sum Method ◽  
Design Variables ◽  
The Cost

In order to decrease the cost of the material and energy during the forging process, multiple preform die shape optimization design was carried out in this paper. Based on the FEM, a sensitivity analysis method was used to perform the optimization procedure. The shape of the forging and deforming force of the final forging was used to express the cost of material and energy respectively. Using the weighted sum method, the total objective function was gotton. The coordinates of the control point of the B-spline used to represent the preform die shape was determined as the optimization design variable. The sensitivity equations of the total objective function with respect to the design variables was developed. The multiple objective perform design optimization software was developed by FORTRAN language. And then, the preform die shape of an H-shaped forging process is optimized. The total objective function, sub-objective function, the shape of the preform die and the final forging during the optimization were given. After the optimiztion, a near net shape forging was obtained. At the same time, the deforming force decreased. The optimization results are very satisfactory.

scholarly journals Iso-geometric shape optimization of magnetic density separators

2014 ◽  
Vol 33 (4) ◽  
pp. 1416-1433 ◽  
Author(s):  
Nguyen Dang Manh ◽  
Anton Evgrafov ◽  
Jens Gravesen ◽  
Domenico Lahaye
Keyword(s):  
Magnetic Field ◽  
Shape Optimization ◽  
Design Problem ◽  
Mass Density ◽  
Linear Optimization ◽  
Optimization Procedure ◽  
Waste Recycling ◽  
Geometric Shape ◽  
End Effects ◽  
Content Type

Purpose – The waste recycling industry increasingly relies on magnetic density separators. These devices generate an upward magnetic force in ferro-fluids allowing to separate the immersed particles according to their mass density. Recently, a new separator design has been proposed that significantly reduces the required amount of permanent magnet material. The purpose of this paper is to alleviate the undesired end-effects in this design by altering the shape of the ferromagnetic covers of the individual poles. Design/methodology/approach – The paper represents the shape of the ferromagnetic pole covers with B-splines and defines a cost functional that measures the non-uniformity of the magnetic field in an area above the poles. The authors apply an iso-geometric shape optimization procedure, which allows us to accurately represent, analyze and optimize the geometry using only a few design variables. The design problem is regularized by imposing constraints that enforce the convexity of the pole cover shapes and is solved by a non-linear optimization procedure. The paper validates the implementation of the algorithm using a simplified variant of the design problem with a known analytical solution. The algorithm is subsequently applied to the problem posed. Findings – The shape optimization attains its target and yields pole cover shapes that give rise to a magnetic field that is uniform over a larger domain. Research limitations/implications – This increased magnetic field uniformity is obtained at the cost of a pole cover shape that differs per pole. This limitation has negligible impact on the manufacturing of the separator. The new pole cover shapes therefore lead to improved performance of the density separation. Practical implications – Due to the larger uniformity the generated field, these shapes should enable larger amounts of waste to be processed than the previous design. Originality/value – This paper treats the shapes optimization of magnetic density separators systematically and presents new shapes for the ferromagnetic poles covers.

scholarly journals Shape optimization of road tunnel cross-section by simulated annealing

2016 ◽  
Vol 38 (2) ◽  
pp. 47-52 ◽  
Author(s):  
Maciej Sobótka ◽  
Michał Pachnicz
Keyword(s):  
Simulated Annealing ◽  
Shape Optimization ◽  
Cross Section ◽  
Optimization Procedure ◽  
In Situ Stress ◽  
Optimal Topology ◽  
Road Tunnel ◽  
Optimal Shapes ◽  
Stress Ratios ◽  
Tunnel Cross Section

Abstract The paper concerns shape optimization of a tunnel excavation cross-section. The study incorporates optimization procedure of the simulated annealing (SA). The form of a cost function derives from the energetic optimality condition, formulated in the authors’ previous papers. The utilized algorithm takes advantage of the optimization procedure already published by the authors. Unlike other approaches presented in literature, the one introduced in this paper takes into consideration a practical requirement of preserving fixed clearance gauge. Itasca Flac software is utilized in numerical examples. The optimal excavation shapes are determined for five different in situ stress ratios. This factor significantly affects the optimal topology of excavation. The resulting shapes are elongated in the direction of a principal stress greater value. Moreover, the obtained optimal shapes have smooth contours circumscribing the gauge.

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