Shape optimisation using CAD linked free-form deformation

2012 ◽  
Vol 116 (1183) ◽  
pp. 915-939 ◽  
Author(s):  
A. Nurdin ◽  
N. W. Bressloff ◽  
A. J. Keane ◽  
C. M. E. Holden
Keyword(s):  
Computer Aided Design ◽  
Shape Representation ◽  
Free Form ◽  
Shape Optimisation ◽  
Design Variables ◽  
Free Form Deformation ◽  
Flexible Deformation ◽  
Set Up ◽  
Passenger Aircraft

AbstractFree-form deformation (FFD) is a method first introduced within the graphics industry to enable flexible deformation of geometric models. FFD uses an R3 to R3 mapping of a deformable space to the global Cartesian space to produce the geometry deformation. This method has been extensively used within the design optimisation field as a shape parameterisation technique. Typically it has been used to parameterise analysis meshes, where new design geometries are produced by deforming the original mesh. This method allows a concise set of design variables to be used while maintaining a flexible shape representation. However, if a computer aided design (CAD) model of the resulting geometry is required, reverse engineering techniques would need to be utilised to recreate the model from the deformed mesh. This paper extends the use of FFD within an optimisation routine by using FFD to directly parameterise a CAD geometry. Two methods of linking the FFD methods with the CATIA V5 CAD package are presented. Each CAD integration technique is then critiqued with respect to shape optimisation. Finally the set-up and initialisation of a case study is illustrated. The case study chosen is the aerodynamic optimisation of the wing-fuselage junction of a typical passenger aircraft.

Adjoint-based aerodynamic drag minimisation with trim penalty

2021 ◽  
pp. 1-25
Author(s):  
S. Shitrit
Keyword(s):  
Drag Reduction ◽  
Aerodynamic Drag ◽  
Lift Coefficient ◽  
Free Form ◽  
Shape Optimisation ◽  
Control Points ◽  
Aerodynamic Shape ◽  
Design Variables ◽  
Gradient Based ◽  
Mesh Warping

Abstract The aerodynamic performance of conventional aircraft configurations are mainly affected by the wing and horizontal tail. Drag reduction by shape optimisation of the wing, while taking into account the aircraft trimmed constraint, has more benefit than focusing solely on the wing. So in order to evaluate this approach, the following study presents results of a single and multipoint aerodynamic shape optimisation of the wing-body-tail configuration, defined by the Aerodynamic Design Discussion Group (ADODG). Most of the aerodynamic shape optimisation problems published in the last years are focused mainly on the wing as the main driver for performance improvement, with no trim constraint and/or excess drag obtained from the fuselage, fins or other parts. This work partially fills this gap by an investigation of RANS-based aerodynamic optimisation for transonic trimmed flight. Mesh warping and geometry parametrisation is accomplished by fitting the multi-block structured grid to a B-spline volumes and performing the mesh movement by using surface control points embedded within the free-form deformation (FFD) volumes. A gradient-based optimisation algorithm is used with an adjoint method in order to compute the derivatives of the objective and constraint functions with respect to the design variables. In this work the aerodynamic shape optimisation of the CRM wing-body-tail configuration is investigated, including a trim constraint that is satisfied by rotating the horizontal tail. The shape optimisation is driven by 432 design variables that envelope the wing surface, and 120 shape variables for the tail, as well as the angle of attack and tail rotation angles. The constraints are the lift coefficient, wing’s thickness controlled by 1,000 control points, and the wing’s volume. For the untrimmed configuration the drag coefficient is reduced by 5.76%. Optimising the wing with a trim condition by tail rotation results in shock-free design with a considerably improved drag, even better than the untrimmed-optimised case. The second optimisation problem studied is a single and multi-point lift constraint drag minimisation of a gliding configuration wing in transonic viscous flow. The shock is eliminated, reducing the drag of the untrimmed configuration by more than 60%, using 192 design variables. Further robustness is achieved through a multi-point optimisation with more than 45% drag reduction.

Behavior-Form Double Directions Creative Conceptual Design Model and Its Quotient Space Implementation

2008 ◽  
Author(s):  
Yu-Xin Wang ◽  
Yu-Tong Li ◽  
Jian-Wei Wang
Keyword(s):  
Conceptual Design ◽  
Design Process ◽  
Quotient Space ◽  
Basic Structure ◽  
Basic Operation ◽  
Decomposition Tree ◽  
Function Decomposition ◽  
Design Variables ◽  
Set Up

This paper presents a novel indirect matching approach between the function layer and the form layer to enhance the capability for the FBS method to obtain the creative conceptual design results. Firstly, the basic operation actions set, which is composed of the basic operation actions obtained by decomposing each function in the lowest level of the function decomposition tree in the FBS model into the sub-functions, in the function layer is regrouped dynamically. This behavior regroup process has introduced the new design variables into the conceptual design process and leads the behavior creativity to produce. On the other hand, considering the multi-functions for each basic structure to have and representing these functions with the basic operation actions, then the basic operation actions set in the form layer is set up. Dynamic regrouping this set in the form layer, the new design variables has been introduced into the conceptual design process, and leads the form creativity to produce. Through the above behavior-form double directions creative process, the solution scope of the conceptual design is enlarged obviously. Therefore, the method present in this paper has enough capability to obtain the creative conceptual results. Furthermore, the model presented in this paper is represented with the quotient space mathematically. The case study has shown that in the function layer, through adjusting the attribute function, which determines the partition grain of the basic operation actions set in the function layer or in the form layer, the new behaviors can be generated.

A Dual Environment for 3D Modeling With User-Defined Free Form Features

2007 ◽  
Author(s):  
Thomas R. Langerak ◽  
Joris S. M. Vergeest
Keyword(s):  
Computer Aided Design ◽  
Shape Representation ◽  
Target Surface ◽  
Free Form ◽  
Dynamic Feature ◽  
Cad Models ◽  
Form Features ◽  
Definition Of ◽  
High Level ◽  
Aided Design

Modeling with free form features has become the standard in Computer-Aided Design (CAD). With the increasing complexity of free form CAD models, features offer a high-level approach to modeling shapes. However, in most commercial modeling packages, only a static set of free form features is available. Researchers have tried to solve this problem by coming up with methods for user-driven free form feature definition, but failed to connect their methods to a means to instantiate these user-driven free form features on a target surface. Reversely, researchers have proposed tools for modeling with free form features, but these methods are time-intensive in that they are as of yet unsuitable for pre-defined features. This paper presents a new method for user-driven feature definition, as well as a method to instantiate these user-defined features on a target surface. We propose the concept of a dual environment, in which the definition of a feature is maintained simultaneously with its instance on a target surface, allowing the user to modify the definition of an already instantiated feature. This dual environment enables dynamic feature modeling, in which the user is able to change the definition of instantiated features on-the-fly. Furthermore, the proposed instantiation method is independent from the type of shape representation of the target surface and thereby increases the applicability of the method. The paper includes an extensive application example and discusses the results and shortcomings of the proposed methods.

A Comprehensive Robust Design Approach for Decision Trade-Offs in Complex Systems Design

1999 ◽  
Vol 123 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Monu Kalsi ◽  
Kurt Hacker ◽  
Kemper Lewis
Keyword(s):  
Robust Design ◽  
Systems Design ◽  
Decision Makers ◽  
Engineering Systems ◽  
Trade Offs ◽  
Design Variables ◽  
Complex Engineering ◽  
The Cost ◽  
Passenger Aircraft

In this paper we introduce a technique to reduce the effects of uncertainty and incorporate flexibility in the design of complex engineering systems involving multiple decision-makers. We focus on the uncertainty that is created when a disciplinary designer or design team must try to predict or model the behavior of other disciplinary subsystems. The design of a complex system is performed by many different designers and design teams, each of which may only have control over a portion of the total set of system design variables. Modeling the interaction among these decision-makers and reducing the effect caused by lack of global control by any one designer is the focus of this paper. We use concepts from robust design to reduce the effects of decisions made during the design of one subsystem on the performance of the rest of the system. Thus, in a situation where the cost of uncertainty is high, these tools can be used to increase the robustness, or independence, of the subsystems, enabling designers to make more effective decisions. To demonstrate the usefulness of this approach, we consider a case study involving the design of a passenger aircraft.

Aerodynamic Design Optimization of an Axial Flow Compressor Stator Using Parameterized Free-Form Deformation

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Richard Amankwa Adjei ◽  
WeiZhe Wang ◽  
YingZheng Liu
Keyword(s):  
Genetic Algorithm ◽  
Flow Field ◽  
Design Optimization ◽  
Operating Conditions ◽  
Free Form ◽  
Aerodynamic Design ◽  
Objective Functions ◽  
Aerodynamic Design Optimization ◽  
Design Variables ◽  
Free Form Deformation

AbstractThis paper describes an aerodynamic design optimization of a highly loaded compressor stator blade using parameterized free-form deformation (FFD). The optimization methodology presented utilizes a B-spline-based FFD control volume to map the blade from the object space to the parametric space via transformation operations in order to perturb the blade surface. Coupled with a multi-objective genetic algorithm (MOGA) and a Gaussian process-based response surface method (RSM), a fully automated iterative loop was used to run the optimization on a fitted correlation function. A weighted average reduction of 6.1% and 36.9% in total pressure loss and exit whirl angle was achieved, showing a better compromise of objective functions with smoother blade shape than other results obtained in the open literature. Data mining of the Pareto set of optimums revealed four groups of data interactions of which some design variables were found to have skewed scatter relationship with objective functions and can be redefined for further improvement of performance. Analysis of the flow field showed that the thinning of the blade at midspan and reduction in camber distribution were responsible for the elimination of the focal-type separation vortex by redirecting the secondary flow in an axially forward direction toward the midspan and near the hub endwall downstream. Furthermore, the reduction in exit whirl angle especially at the shroud was due to the mild bow shape which generated radial forces on the flow field thereby reducing the flow diffusion rate at the suction surface corner. This effect substantially delayed or eliminated the formation of corner separation at design and off-design operating conditions. Parameterized FFD was found to have superior benefits of smooth surface generation with low number of design variables while maintaining a good compromise between objective functions when coupled with a genetic algorithm.

scholarly journals OPTIMISATION OF HULL FORM OF OCEAN-GOING TRAWLER

Brodogradnja ◽  
2021 ◽  
Vol 72 (4) ◽  
pp. 33-46
Author(s):  
Cheng Zhao ◽  
◽  
Wei Wang ◽  
Panpan Jia ◽  
Yonghe Xie ◽  
...  
Keyword(s):  
Computer Aided Design ◽  
Free Form ◽  
Deformation Method ◽  
Nsga Ii ◽  
Hull Form ◽  
Free Form Deformation ◽  
Before And After ◽  
Computational Fluid Dynamics Cfd ◽  
Bulbous Bow ◽  
Aided Design

This paper proposes a method for optimising the hull form of ocean-going trawlers to decrease resistance and consequently reduce the energy consumption. The entire optimisation process was managed by the integration of computer-aided design and computational fluid dynamics (CFD) in the CAESES software. Resistance was simulated using the CFD solver and STAR-CCM+. The ocean-going trawler was investigated under two main navigation conditions: trawling and design. Under the trawling condition, the main hull of the trawler was modified using the Lackenby method and optimised by NSGA-II algorithm and Sobol + Tsearch algorithm. Under the design condition, the bulbous bow was changed using the free-form deformation method, and the trawler was optimised by NSGA-Ⅱ. The best hull form is obtained by comparing the ship resistance under various design schemes. Towing experiments were conducted to measure the navigation resistance of trawlers before and after optimisation, thus verifying the reliability of the optimisation results. The results show that the proposed optimisation method can effectively reduce the resistance of trawlers under the two navigation conditions.

Shape optimisation of blended-wing-body underwater gliders based on free-form deformation

2019 ◽  
Vol 15 (3) ◽  
pp. 227-235 ◽  
Author(s):  
Jinglu Li ◽  
Peng Wang ◽  
Huachao Dong ◽  
Xumao Wu ◽  
Xu Chen ◽  
...  
Keyword(s):  
Free Form ◽  
Shape Optimisation ◽  
Underwater Gliders ◽  
Free Form Deformation ◽  
Blended Wing Body

A case study evaluation of a community multidisciplinary team in South East England using a mixed-method approach

2020 ◽  
Vol 70 (suppl 1) ◽  
pp. bjgp20X711569
Author(s):  
Jessica Wyatt Muscat
Keyword(s):  
Mental Health ◽  
Mixed Method ◽  
Social Care ◽  
Free Form ◽  
Normalisation Process Theory ◽  
Multidisciplinary Teams ◽  
Mixed Method Approach ◽  
Health And Social Care ◽  
Method Approach

BackgroundCommunity multidisciplinary teams (MDTs) represent a model of integrated care comprising health, social care, and the voluntary sector where members work collaboratively to coordinate care for those patients most at risk.AimThe evaluation will answer the question, ‘What are the enablers and what are the restrictors to the embedding of the case study MDT into the routine practice of the health and social care teams involved in the project?’MethodThe MDT was evaluated using a mixed-method approach with normalisation process theory as a methodological tool. Both quantitative and qualitative data were gathered through a questionnaire consisting of the NoMAD survey followed by free-form questions.ResultsThe concepts of the MDT were generally clear, and participants could see the potential benefits of the programme, though this was found to be lower in GPs. Certain professionals, particularly mental health and nursing professionals, found it difficult to integrate the MDT into normal working patterns because of a lack of resources. Participants also felt there was a lack of training for MDT working. A lack of awareness of evidence supporting the programme was shown particularly within management, GP, and nursing roles.ConclusionSpecific recommendations have been made in order to improve the MDT under evaluation. These include adjustments to IT systems and meeting documentation, continued education as to the purpose of the MDT, and the engagement of GPs to enable better buy-in. Recommendations were made to focus the agenda with specialist attendance when necessary, and to expand the MDT remit, particularly in mental health and geriatrics.

scholarly journals Hybrid Seven-bar Press Mechanism

2018 ◽  
Vol 12 (3) ◽  
pp. 181-187
Author(s):  
M. Erkan Kütük ◽  
L. Canan Dülger
Keyword(s):  
Genetic Algorithm ◽  
Objective Function ◽  
Design Optimization ◽  
Hybrid System ◽  
Degrees Of Freedom ◽  
Dimensional Synthesis ◽  
Design Variables ◽  
Optimization Study ◽  
Metal Stamping

An optimization study with kinetostatic analysis is performed on hybrid seven-bar press mechanism. This study is based on previous studies performed on planar hybrid seven-bar linkage. Dimensional synthesis is performed, and optimum link lengths for the mechanism are found. Optimization study is performed by using genetic algorithm (GA). Genetic Algorithm Toolbox is used with Optimization Toolbox in MATLAB®. The design variables and the constraints are used during design optimization. The objective function is determined and eight precision points are used. A seven-bar linkage system with two degrees of freedom is chosen as an example. Metal stamping operation with a dwell is taken as the case study. Having completed optimization, the kinetostatic analysis is performed. All forces on the links and the crank torques are calculated on the hybrid system with the optimized link lengths

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