Isogeometric Shape Optimization on Triangulations

2016 ◽  
Author(s):  
Cunfu Wang ◽  
Songtao Xia ◽  
Xilu Wang ◽  
Xiaoping Qian
Keyword(s):  
Shape Optimization ◽  
Optimization Method ◽  
Coarse Mesh ◽  
Mesh Quality ◽  
Numerical Accuracy ◽  
B Spline ◽  
Fine Mesh ◽  
Complex Topology ◽  
Physical Fields ◽  
Bézier Triangles

The paper presents an isogeometric shape optimization method that is based on Bézier triangles. Bézier triangles are used to represent both the geometry and physical fields. For a given physical domain defined by B-spline boundary, triangular Bézier parameterization can be automatically generated. This shape optimization method is thus applicable to structures of complex topology. Due to the use of B-spline parameterization of the boundary, the optimized shape can be compactly represented with a relatively small number of optimization variables. In order to ensure mesh validity during shape optimization, we adopt a bi-level mesh representation, where the coarse mesh is used to maintain mesh quality through positivity of Jacobian ordinates of the Bézier triangles. The fine mesh is used in isogeometric analysis for numerical accuracy. Numerical examples are presented to demonstrate the efficacy of the proposed method.

Comprehensive Design Method for Open or Ducted Propellers for Underwater Vehicles

2021 ◽  
Author(s):  
Spyros A. Kinnas ◽  
Kyungjung Cha ◽  
Seungnam Kim
Keyword(s):  
Design Method ◽  
A Priori ◽  
Optimization Method ◽  
Underwater Vehicles ◽  
Current Approach ◽  
Lattice Method ◽  
B Spline ◽  
Effective Wake ◽  
Propeller Thrust ◽  
Ducted Propellers

A comprehensive method which determines the most efficient propeller blade shapes for a given axisymmetric hull to travel at a desired speed, is presented. A nonlinear optimization method is used to design the blade, the shape of which is defined by a 3-D B-spline polygon, with the coordinates of the B-spline control points being the parameters to be optimized for maximum propeller efficiency, for given effective wake and propeller thrust. The performance of the propeller within the optimization scheme is assessed by a vortex-lattice method (VLM). To account fully for the hull/propeller interaction, the effective wake to the propeller and the hull resistance are determined by analyzing the designed propeller geometry by the VLM, coupled with a Reynolds-Averaged Navier-Stokes (RANS) solver. The optimization method re-designs the optimum blade with the updated effective wake and propeller thrust (taken to be equal to the updated hull resistance), and the procedure continues until convergence of the propeller performance. The current approach does not require knowledge of the wake fraction or the thrust deduction factor, both of which must be estimated a priori in traditional propeller design. The method is applied for a given hull to travel at a desired speed, and the optimum blades are designed for various combinations of propeller diameter and RPM, in the case of open and ducted propellers with provided duct shapes. The effects of the propeller diameter and RPM on the designed propeller thrust, torque, propeller efficiency, and required power are presented and compared with each other in the case of open and ducted propellers. The present approach is shown to provide guidance on the design of propulsors for underwater vehicles, and is applicable to the design of propulsors for surface ships.

Structural topology optimization of bridge girders in cable supported bridges

2018 ◽  
Author(s):  
Mads Baandrup ◽  
Ole Sigmund ◽  
Niels Aage
Keyword(s):  
Topology Optimization ◽  
Large Scale ◽  
Design Method ◽  
Optimization Method ◽  
Bridge Girders ◽  
Structural Topology ◽  
Box Girders ◽  
Box Girder ◽  
Fine Mesh ◽  
Further Development

<p>This work applies a ultra large scale topology optimization method to study the optimal structure of bridge girders in cable supported bridges.</p><p>The current classic orthotropic box girder designs are limited in further development and optimiza­ tion, and suffer from substantial fatigue issues. A great disadvantage of the orthotropic girder is the loads being carried one direction at a time, thus creating stress hot spots and fatigue problems. Hence, a new design concept has the potential to solve many of the limitations in the current state­ of-the-art.</p><p>We present a design method based on ultra large scale topology optimization. The highly detailed structures and fine mesh-discretization permitted by ultra large scale topology optimization reveal new design features and previously unseen eff ects. The results demonstrate the potential of gener­ ating completely different design solutions for bridge girders in cable supported bridges, which dif­ fer significantly from the classic orthotropic box girders.</p><p>The overall goal of the presented work is to identify new and innovative, but at the same time con­ structible and economically reasonable, solutions tobe implemented into the design of future cable supported bridges.</p>

A new jig-shape optimization method for the high aspect ratio wing

2018 ◽  
Vol 91 (1) ◽  
pp. 124-133
Author(s):  
Zhe Yuan ◽  
Shihui Huo ◽  
Jianting Ren
Keyword(s):  
Aspect Ratio ◽  
Shape Optimization ◽  
High Aspect Ratio ◽  
Optimization Design ◽  
Design Method ◽  
Aircraft Design ◽  
Optimization Method ◽  
Attack Angle ◽  
Structural Deformation ◽  
Content Type

Purpose Computational efficiency is always the major concern in aircraft design. The purpose of this research is to investigate an efficient jig-shape optimization design method. A new jig-shape optimization method is presented in the current study and its application on the high aspect ratio wing is discussed. Design/methodology/approach First, the effects of bending and torsion on aerodynamic distribution were discussed. The effect of bending deformation was equivalent to the change of attack angle through a new equivalent method. The equivalent attack angle showed a linear dependence on the quadratic function of bending. Then, a new jig-shape optimization method taking integrated structural deformation into account was proposed. The method was realized by four substeps: object decomposition, optimization design, inversion and evaluation. Findings After the new jig-shape optimization design, both aerodynamic distribution and structural configuration have satisfactory results. Meanwhile, the method takes both bending and torsion deformation into account. Practical implications The new jig-shape optimization method can be well used for the high aspect ratio wing. Originality/value The new method is an innovation based on the traditional single parameter design method. It is suitable for engineering application.

scholarly journals Sizing and shape optimization material use in 10 bar trusses

2021 ◽  
Vol 343 ◽  
pp. 04004
Author(s):  
Nenad Petrović ◽  
Nenad Kostić ◽  
Vesna Marjanović ◽  
Ileana Ioana Cofaru ◽  
Nenad Marjanović
Keyword(s):  
Genetic Algorithm ◽  
Shape Optimization ◽  
Cross Sections ◽  
Optimization Model ◽  
Structural Characteristics ◽  
Optimization Method ◽  
Truss Optimization ◽  
Algorithm Optimization ◽  
Sizing Optimization ◽  
Bill Of Materials

Truss optimization has the goal of achieving savings in costs and material while maintaining structural characteristics. In this research a 10 bar truss was structurally optimized in Rhino 6 using genetic algorithm optimization method. Results from previous research where sizing optimization was limited to using only three different cross-sections were compared to a sizing and shape optimization model which uses only those three cross-sections. Significant savings in mass have been found when using this approach. An analysis was conducted of the necessary bill of materials for these solutions. This research indicates practical effects which optimization can achieve in truss design.

Structure Vibration Shape Optimization Based on Power Flow Response Analysis

2014 ◽  
Vol 490-491 ◽  
pp. 712-718
Author(s):  
Xue Bao Xia ◽  
Yang Xiang ◽  
Shao Wei Wu
Keyword(s):  
Shape Optimization ◽  
Mode Shape ◽  
Power Flow ◽  
Flow Analysis ◽  
Optimization Method ◽  
Weight Coefficient ◽  
Surface Shape ◽  
Response Analysis ◽  
Flow Response ◽  
Vibration Power Flow

Power flow analysis is a method to describe the dynamic behavior of structures by taking not only the amplitude of exciting force and velocity response into account, but also the phase between the two qualities. Shape optimization is an effective method to reduce vibration level. By choosing the vibration power flow as design objective, a shape optimization method of structure is presented. The structure surface is restructured with a series of mode shape superposition. By using genetic algorithm, the weight coefficient of each mode shape is optimized to get the best surface shape with minimum power flow response. Some examples are demonstrated to verify the efficiency and accuracy of the method.

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