Shape Design Method Research Articles

Parametric design and optimization of high speed train nose

Aiming at shortening the design period and improve the design efficiency of the nose shape of high speed trains, a parametric shape optimization method is developed for the design of the nose shape has been proposed in the present paper based on the VMF parametric approach, NURBS curves and discrete control point method. 33 design variables have been utilized to control the nose shape, and totally different shapes could be obtained by varying the values of design variables. Based on the above parametric method, multi-objective particle swarm algorithm, CFD numerical simulation and supported vector machine regression model, multi-objective aerodynamic shape optimization has been performed. Results reveal that the parametric shape design method proposed here could precisely describe the three-dimensional nose shape of high speed trains and could be applied to the concept design and optimization of the nose shape. Besides, the SVM regression model based the multi-points criterion could accurately describe the non-linear relationship between the design variables and objectives, and could be generally utilized in other fields. No matter the simplified model or the real model, the aerodynamic performance of the model after optimization has been greatly improved. Based on the SVR model, the nonlinear relation between the aerodynamic drag and the design variables is obtained, which could provide guidance for the engineering design and optimization.

An airplane jig shape design method based on high fidelity aeroelastic simulation

This paper develops a jig-shape design method for the elastic wing of the commercial aircraft with high aspect ratio. Two optimization steps are involved in the design method to optimize the jig shape of the elastic wing with the user-desired cruise aerodynamic performance. The real aeroelastic simulation becomes the fundamental of the design procedure. Structural mesh based CFD solver has been applied to simulate the transonic flow with high fidelity. Finite element based structural model of wing with complex configuration is constructed, and the flexibility matrix is evaluated to predict the deflection of the wing. The high-efficient mesh deformation technique and the data exchange interface between CFD and CSD are implemented, which improves the efficiency and accuracy of current approach. The jig shape design of a baseline commercial aircraft is presented, and the numerical simulation shows that the design method is strong enough to obtain the optimized jig shape efficiently.

원형소재를 이용한 프로파일 다단 형상인발 공정설계

Multi-pass shape drawing is very important to produce steel profiles in round samples. In the current study, a process design system is developed for a multi-pass shape drawing. In general, the number of passes for a multi-pass shape drawing is 2 to 3 when the reduction ratio, drawing stress, and productivity are considered. Therefore, calculating the drawing stress and designing the intermediated die shapes are very important. In order to calculate the drawing stress, a shape drawing load prediction method is proposed using a general axisymmetric drawing load prediction model. An intermediate die shape design method is proposed using the initial and the final product shapes. Based on this analysis, a process design system is developed for multi-pass shape drawing for steel profiles. The system works with AutoCAD. The system was applied to design a shape drawing of a spline.

Enhanced decentralized PI control for fluidized bed combustor via advanced disturbance observer

Motivation of this paper is to propose an engineering friendly control strategy to handle the various difficulties in fluidized bed combustor (FBC). The control objectives of FBC and the difficulties arisen from nonlinear dynamics, frequent disturbances and strong coupling are first formulated. The capability of the disturbance observer (DOB) to handle the nonlinearity and disturbances is analyzed and the decoupling effect of DOB is revealed in terms of equivalent transfer function. For the power loop, a robust loop shaping design method is proposed to balance the performance and robustness of DOB. For the temperature loop, the DOB filter is designed based on H∞ optimization. Abilities of DOB are confirmed by numerical simulations. A water tank experiment is designed to show the simplicity of implementing DOB in an industrial Distributed Control System. Finally, a global simulation on the FBC process demonstrates that, compared with the conventional PI scheme, the DOB-enhanced PI strategy achieves overall improvement and can even be comparable with the complex Model Predictive Control in some aspects.

Material distribution resembled level set method for optimal shape design of Stokes flow

Inspired by the work of Borrvall and Petersson [1], we propose a novel algorithm for optimal shape design problem of two-dimensional Stokes flow in order to minimize a given objective functional. The setting of the optimization problem is in the most general form, which makes this work a nontrivial extension of [1]. Borrowed idea of material distribution method from shape or topology optimization in solid mechanics, we employ an implicit coupled level set method to track the interface (boundary) of the fluid flow. Although our target application in this work is optimal shape design of Stokes flow, the proposed method can be generalized to solve other shape or topology optimization problems in fluid mechanics need no further additional effort. The promising features of the proposed algorithm are illustrated by two numerical examples.

Variational surface design under normal field guidance

Abstract This paper proposes a novel method for shape design of a Bézier surface with given boundary curves. The surface is defined as the minimizer of an extended membrane functional or an extended thin plate functional under the guidance of a specified normal field together with an initial prescribed surface. For given boundary curves and the guiding normal field, the free coefficients of a Bézier surface are obtained by solving a linear system. Unlike previous PDE based surface modeling techniques which construct surfaces just from boundaries, our proposed method can be used to generate smooth and fair surfaces that even follow a specified normal field. Several interesting examples are given to demonstrate the applications of the proposed method in geometric modeling. Highlights Two extended energy functionals are proposed for variational surface modeling. The guiding normal field can be used to control the shapes of the variational surfaces efficiently. The proposed technique can be used for various modeling purposes like editing, hole filling or transition surface design.

2A1-M07 進化型計算によるモジュラーロボットの自動設計 : 優良個体の形態の解析

The purpose of this research is to develop an automatic design method for hardware and software of Modular robot. In this paper, the genetic algorithm is applied as the design method for shape and behavior of a virtual mobile modular robot. The purpose of the design of modular robot is to track the light source. Designed modular robots are simulated in a three-dimensional virtual physics space, and evaluated by light source tracking capability. As a result, an appropriate shape and behavior for virtual robots is acquired.

Parallel Control to Fragments of a Cylindrical Structure Driven by Explosive inside

By analyzing the fragmentation distributions of a cylindrical structure and a specific structure, the necessity of parallel control to the fragments is presented. The shell shape of structures has an influence on the fragment spatial distribution. A new design method for the shell shape is proposed. To facilitate the establishment of the numerical model and the machining for relative experiments, the mathematical description of the theoretical calculated generatrix of the shell is simplified. The fragment spraying processes of the designed structures are simulated, and end effects are analyzed. Based on the theoretical design and plentiful simulation data, the relationships between the size of the parallel fragmentation structure and the optimized curvature radius of the shell are expressed by an equation. The equation is validated by numerical means and can be a reliable reference to the design of the parallel fragmentation structure.

Research on the Design and Modification of Asymmetric Spur Gear

A design method for the geometric shape and modification of asymmetric spur gear was proposed, in which the geometric shape and modification of the gear can be obtained directly according to the rack-cutter profile. In the geometric design process of the gear, a rack-cutter with different pressure angles and fillet radius in the driving side and coast side was selected, and the generated asymmetric spur gear profiles also had different pressure angles and fillets accordingly. In the modification design of the gear, the pressure angle modification of rack-cutter was conducted firstly and then the corresponding modified involute gear profile was obtained. The geometric model of spur gears was developed using computer-aided design, and the meshing process was analyzed using finite element simulation method. Furthermore, the transmission error and load sharing ratio of unmodified and modified asymmetric spur gears were investigated. Research results showed that the proposed gear design method was feasible and desired spur gear can be obtained through one time rapid machining by the method. Asymmetric spur gear with better transmission characteristic can be obtained via involute modification.

A STUDY ON OPTIMIZATION OF SHIP HULL FORM BASED ON NEURO-RESPONSE SURFACE METHOD (NRSM)

Building large and eco-friendly ships has become a clear trend in the ship building industry. Research to minimize ship resistance has actively been investigated for energy savings and environmental protection. However, optimization of the full geometry, while taking into account the hydrodynamic performance is difficult because extensive time is needed to calculate the performance factors, such as the resistance and propulsion. Hence we suggest an optimal design framework based on the neuro-response surface method (NRSM) for optimal shape design in consideration of hydrodynamic performance. The optimization algorithm of the constructed framework consists of the back-propagation neural network (BPN) and the non-dominated sorting genetic algorithm-II (NSGA-II). Using the framework, we performed a case study to optimize the hull form of a 4300TEU container ship with consideration of wave resistance, viscous pressure resistance, and wake fraction.

Inverse shape design via a new physical-based iterative solution strategy

Inverse shape design in the context of fluid flow problems is commonly referred to the determination of the boundary shape corresponding to a given target surface pressure. Designers naturally turn to this class of problems whenever there are concerns regarding pressure-related phenomena such as cavitation, separation, shock waves, surface loading, etc. Numerical solution is often unavoidable and, therefore, three computational tools, i.e. a grid generator, a flow field solver and a shape updater, are required in an iterative solution procedure. In all existing iterative inverse design methods, the shape updater comes from separate mathematical or physical considerations that are not derived solely from the equations governing the flow field. In this paper, the currently used strategies to solve inverse shape design problems are categorized and reviewed, and then a truly physical-based iterative inverse shape design method is introduced in which the governing equations are not only used in the flow solver, but are also employed to update the shape. To explore the features of the proposed method, it is used to solve a number of shape design problems. The previously developed direct shape design method and a typical iterative solution approach are also explained and used for the solution of the same problems for the purpose of comparison. Computational results reveal that the proposed algorithm has a two to three times faster convergence rate as compared to the iterative algorithm. The convergence rate of the proposed algorithm usually stalls after three or two orders of magnitude reduction of the residual. For the test cases in this study, the direct design method is the fastest and most accurate method as compared to other algorithms. Both in-house developed computer codes and commercial software are used as a field solver to show the general applicability of the proposed method in its current state of development.

The Reverse Modeling Analysis and Design on Compression Molding Bodies

To solve the problem it is difficult to accurately measure the curve surface, the forming mechanism of reverse engineering modeling approach is studied. Using the non-contact measurement of laser scanner, the point cloud data of the compression molding bodies is obtained, and it is introduced into the three-dimensional software CATIA to generate 3D model according to the molding processing point cloud and compression molding mechanism. In the last to generate the complete engineering drawings. Comparing the traditional design method, the method is mainly used for 3D parts reconstruction and design in surface shape is difficult to accurately expressed or unknown component shape design methods.

An asymptotic numerical method for inverse elastic shape design

Inverse shape design for elastic objects greatly eases the design efforts by letting users focus on desired target shapes without thinking about elastic deformations. Solving this problem using classic iterative methods (e.g., Newton-Raphson methods), however, often suffers from slow convergence toward a desired solution. In this paper, we propose an asymptotic numerical method that exploits the underlying mathematical structure of specific nonlinear material models, and thus runs orders of magnitude faster than traditional Newton-type methods. We apply this method to compute rest shapes for elastic fabrication, where the rest shape of an elastic object is computed such that after physical fabrication the real object deforms into a desired shape. We illustrate the performance and robustness of our method through a series of elastic fabrication experiments.

Complex CAD surface shape design using semantic features

To a large extent, the success of the product shape design depends on whether the geometric modeling systems can satisfy more and more complicated design demands in the engineering field. This paper proposes a shape design method based on semantic features for complex CAD surface. By the proposed method, we can easily meet the complicated design requirements, since the semantic can effectively represent the design intent. We discussed three aspects in shape design using semantic features, which are semantic design demands of the target surface, geometric constraints in accordance with semantic features, and surface shape deformation under the geometric constraints, respectively. The basic semantic features of geometric models drive the deformation of the target surface shape by changing the related constraint, and the desirable features are added to the CAD surface shape. The examples of the car shape design are presented to verify the effectives of our method.

ℋ∞-Controller Design Methods Applied to One Joint of a Flexible Industrial Manipulator

Control of a flexible joint of an industrial manipulator using ℋ∞ design methods is presented. The considered design methods are i) mixed-ℋ∞ design, and ii) ℋ∞ loop shaping design. Two different controller configurations are examined: one uses only the actuator position, while the other uses the actuator position and the acceleration of the end-effector. The four resulting controllers are compared to a standard pid controller where only the actuator position is measured. The choices of the weighting functions are discussed in details. For the loop shaping design method, the acceleration measurement is required to improve the performance compared to the pid controller. For the mixed-**ℋ∞ method it is enough to have only the actuator position to get an improved performance. Model order reduction of the controllers is briefly discussed, which is important for implementation of the controllers in the robot control system.

Mapped B-spline basis functions for shape design and isogeometric analysis over an arbitrary parameterization

It is well-known that B-spline surfaces are defined by a regular array of control vertices. In case of models with arbitrary topology, it is extremely difficult to maintain continuity conditions among neighboring surfaces. The scenario is also true for applications in isogeometric analysis (IGA). This paper presents a novel method for shape design and isogeometric analysis from a quadrilateral control mesh of arbitrary topology using mapped B-spline basis functions. Based on an arbitrary input quadrilateral control mesh, a global parameterization of the final surface is first defined through a Gravity Center Method (GCM). A re-parameterization method is then applied to map a B-spline basis function to others that are explicitly defined and are tailored to each of the control vertices which can be either regular or extraordinary ones. The final surface is defined by all the input control vertices with their corresponding mapped basis functions. For practical implementation, the surface can be evaluated patch by patch. Depending on the order of the B-spline basis function used for mapping to others, the global continuity of the resulting surface, including at extraordinary points, can be arbitrary higher order. In the present paper, a uniform cubic B-spline basis function is used and the resulting surface is globally C2 continuous. Several numerical examples are provided to demonstrate the proposed method for both shape design and isogeometric analysis.

Study of the Design Method for The Shape of Charge Curve of the Double Focusing Warhead

Study of the Design Method for The Shape of Charge Curve of the Double Focusing Warhead

Free-Form Optimization Method for Shape Design of Framed Structure

In this paper, a parameter-free shape optimization method is proposed for designing the smooth optimal free-form of a 3D framed structure. A stiffness design problem where the compliance is minimized under a volume constraint is solved as an example of a shape design problem. The optimum design problem is formulated as a distributed-parameter shape optimization problem under the assumptions that each member is varied in the out-of-plane direction to the centroidal axis and the cross section is prismatic. The shape gradient function and the optimality conditions for this problem are then theoretically derived. The optimal curvature distribution is determined by applying the derived shape gradient function to each member as a pseudo distributed force to vary the frame, while minimizing the objective functional. We call this method the free-form optimization method for frame, a gradient method in the Hilbert space. The validity and practical utility of this method were verified through several design examples. It was confirmed that axial-force-carrying structures was obtained by this method.

A new shape design method of salt cavern used as underground gas storage

A new model used to design the shape and dimension of salt cavern gas storage is proposed in the paper. In the new model, the cavern is divided into two parts, namely the lower and upper structures, to design. The concepts of slope instability and pressure arch are introduced into the shape design of the lower and upper structures respectively. Calculating models are established according to the concepts. Field salt cavern gas storage in China is simulated as examples, and its shape and dimension are proposed. The effects of gas pressure, friction angle and cohesion of rock salt on the cavern stability are discussed. Moreover, the volume convergence, displacement, plastic volume rate, safety factor, and effective strain are compared with that of three other existing shapes salt caverns to validate the performance of newly proposed cavern. The results show that the max. gas pressure determines the shape and dimension of cavern lower structure, while the min. gas pressure decides that of cavern upper structure. With the increase of friction angle and cohesion of rock salt, the stability of salt cavern is increased. The newly proposed salt cavern gas storage has more notable advantages than the existing shapes of salt cavern in volume convergence, displacement, plastic volume rate, safety factor, and effective strain under the same conditions.

Bionic Shape Design of Quantify Products Based on Genetic Algorithm

Bionic shape design based on genetic research could inherent and improve the positive parts of present product shape and absorb the natural characters from the biological shape, which provide a new quantifying shape design method for the designers. Based on a simple example of clip shape and shark shape, this essay realize the quantifying process of bionic shape design based on MATLAB platform through a process which firstly deal with the pre-process, scilicet proportional zooming for the creature shape model, identification of the chromosome and adaptability function rules, and then realize the process based on crossover rules and mutation rules on MATLAB.