基于遗传算法的回转体头部线型低噪优化设计

基于边界层理论和转捩区声辐射理论,利用Krane偶极子声源模型对Liepmann单极子声源模型进行改进,结合回转体头部线型设计理论,采用标准遗传算法,建立了一套完整的回转体头部线型低噪优化设计的方法和模型。优化结果表明：找到了全局最优解,最大降噪量约为11.8%。     

Stress singularities in bimaterial bodies of revolution

An eigenfunction expansion solution is first developed for determining the stress singularities of bimaterial bodies of revolution by directly solving the equilibrium equations of three-dimensional elasticity in terms of displacement functions. The characteristic equations are explicitly given for determining the stress singularities in the vicinity of the interface corner of two intersecting bodies of revolution having a sharp corner with free boundary conditions along the corner. The characteristic equations are found to be equivalent to a combination of the characteristic equations for plane elasticity problems and St. Venant torsion problems. The strength of stress singularities varying with the interface angles is also investigated. The first known asymptotic solutions for the displacement and stress fields are also explicitly shown for some interface angles. The present results will be useful not only for understanding the singularity behaviors of stresses in the vicinity of a revolution interface corner, but also for developing accurate numerical solutions with fast convergence for stress or vibration analysis of a body of revolution having an interface corner.     

Shape optimal design of structures: an efficient shape representation concept

This paper describes a shape representation concept that may be used in general shape optimization procedures. It relies on the assumption that the finite element mesh is defined as a convective mesh following automatically the shape changes of a conveniently parameterized body. Suitable parameterization of the body is achieved by combining the design element technique and a convenient design element. The design element is defined as a rational Bézier body. It represents a general‐purpose design element that may serve as the geometrical data provider for the response and sensitivity analysis for virtually any finite element type. Practical implementation of the proposed approach for space frame structures is discussed in detail. The validity of the proposed approach as well as the use of a body‐like design elements are illustrated by three numerical examples. Copyright © 2000 John Wiley & Sons, Ltd.     

A mathematical formulation for interface-based modular product design with geometric and weight constraints

Since customer preferences change rapidly, there is a need for design processes with shorter product development cycles. Modularization plays a key role in achieving mass customization, which is crucial in today's competitive global market environments. Standardized interfaces among modularized parts have facilitated computational product design. To incorporate product size and weight constraints during computational design procedures, a mixed integer programming formulation is presented in this article. Product size and weight are two of the most important design parameters, as evidenced by recent smart-phone products. This article focuses on the integration of geometric, weight and interface constraints into the proposed mathematical formulation. The formulation generates the optimal selection of components for a target product, which satisfies geometric, weight and interface constraints. The formulation is verified through a case study and experiments are performed to demonstrate the performance of the formulation.     

A unified parametric design approach to structural shape optimization

This paper presents a general parametric design approach for 2-D shape optimization problems. This approach has been achieved by integrating practical design methodologies into numerical procedures. It is characterized by three features: (i) automatic selection of a minimum number of shape design variables based on the CAD geometric model; (ii) integration of sequential convex programming algorithms to solve equality constrained optimization problems; (iii) efficient sensitivity analysis by means of the improved semi-analytical method. It is shown that shape design variables can be either manually or systematically identified with the help of equality constraints describing the relationship between geometric entities. Numerical solutions are performed to demonstrate the applicability of the proposed approach. A discussion of the results is also given:     

A morphing method for shape generation and image prediction in product design

A shape morphing and image prediction method for product design is proposed in this article, in which a feature-based method is first used to construct 3-D CAD models of a product, then new shapes are generated with a shape morphing method and the images of the morphed shapes are analyzed using modified gray theory with Fourier residual correction. With the aid of this model, the designer can quickly obtain a product form and its corresponding image to help him/her to design the required product. Though LCD monitor design is applied, this method can also be used to develop other products.     

桅杆首阶固有频率控制与构形设计

基于Timoshenko梁理论，提出筒形桅杆首阶固有频率控制设计原理。依据该原理，采用Transfermatrix算法，研究了直壁式、外凸式及双曲式三种构形的桅杆首阶固有频率的变化规律，发现在桅杆高度、质量、顶部及底部截面边长相同的情况下，外凸式构形具有最大的首阶固有频率值。     

A method of measuring the deviations of the shape of a shell of revolution

A method of measuring the deviations of the shape of large shells of revolution that makes it possible to control the shape of the shell on all stages of manufacturing, repair, and use is considered. The method is based on measurements of the variations of the curvature at points situated uniformly or nonuniformly along the perimeter of transverse control sections. __________ Translated from Izmeritel’naya Tekhnika, No. 3, pp. 33–35, March, 2007.     

A continuum approach for second-order shape design sensitivity of elastic solids with loaded boundaries

A second-order shape design sensitivity analysis (DSA) method applicable to the shape change on the loaded boundaries is derived for three-dimensional linear elastic solids using a continuum method with the material derivative. The continuum method is also used to derive mixed second-order variations of stress and displacement performance measures with respect to shape design variables and distribution of non-conservative traction loads, and also with respect to shape design variables and material properties. A shape design acceleration field is defined for the second-order shape design sensitivity. Both direct differentiation and hybrid methods are presented in this paper. A numerical method, which can be implemented using established finite element analysis (FEA) codes, is developed. The feasibility and accuracy of the proposed second-order shape DSA method has been demonstrated by solving a structural example-doubly curved arch dam.