异形马口铁罐成型新工艺

德国制罐商Rasselstein Hoesch(RH)在Inter-pack’96国际包装展览会上展出了二片罐和三片罐不同造型的专利新工艺.它将正常的二片马口铁罐罐身,通过在冷成型作业中,以水力压延,使罐身圆柱体由原来的20%扩张到80%,从而使罐体造型几乎可以创造出任何形状的地步.在预成型阶段,将经过深冲拔和拉伸成型的罐身放入一个壳形模,以水压使罐壁在模腔内有控制地膨胀.     

弹体毛坯热冲拔工艺

目的设计弹体毛坯热冲拔成形工艺方案。方法将冲子压入加热后的钢坯,使钢坯在压力作用下充满模腔,压成盂形,然后套在引伸冲子通过一串直径逐渐缩小的模圈,使弹体拉长、直径减小、壁厚减薄,获得合理的弹体毛坯尺寸,生产出合格毛坯。分析弹体毛坯冲拔成形原理、温度控制、工装设计及冲拔过程中的金属流动规律,根据体积不变原理,计算出冲拔毛坯尺寸。结果通过批量试制,根据冲拔过程中常见问题的控制措施,优化了冲拔工艺参数,实现了弹体毛坯热冲拔成形。结论通过冲拔原理分析、毛坯及工装设计,形成了热冲拔设计规范,该弹体毛坯热冲拔工艺可行。     

产品体验视角下的汽车造型评价研究

目的从体验角度探讨汽车造型评价。方法在前人研究的基础上,提出了体验视角下的多层次汽车造型评价模型,并将此模型与TOPSIS数学决策方法结合起来,共同构成了一种产品体验视角下的汽车造型设计评价方法。结论该方法从体验角度融合了感性方法和理性方法 ,形成了一套可操作的体验评价流程,并最终进行了实验验证。该方法已应用在了基于进化算法的计算机辅助生成汽车造型设计中,并发挥了重大作用,此方法亦可独立应用于其他工业设计产品造型评价中。     

工业产品造型中布尔运算的运用

布尔运算是造型的基本算法之一,它有较高的通用性和低效率的特点.文章分析了布尔运算低效及呆板的原因,并通过解析造型实例,提出了减少操作修改和提高布尔运算效率的组织策略和运用技巧,这在生产企业的设计与制造中还是有可观的效益.     

基于APDL的托盘支腿结构承载能力的非线性屈曲分析

目的探究新型重载纤维模塑托盘支腿结构的承载能力及非线性屈曲变化规律。方法依据制备的纤维模塑材料参数为基础,通过编写Ansys APDL程序,对设计的重载纤维模塑托盘支腿结构进行压缩载荷下的非线性屈曲模拟。结果 Anays模拟与实验得到的极限载荷值误差均在5.2%以内,具有很好的模拟精度。重载纤维模塑托盘支腿在压屈变形过程中,最大应力-应变变化表现为4个阶段,即弹性阶段、强化阶段、屈曲变形阶段和应力失效阶段。不同尺径支腿的屈曲变形阶段应力均维持在12.69 MPa左右,低于材料极限强度。增大壁厚或拔模角度,能增强支腿后屈曲变形阶段的承载能力;增大壁厚或减小拔模角度,能增大支腿的极限载荷。拔模角度为1.5°~2.0°,倒圆角半径为9~15 mm时,有利于支腿模塑工艺的实现及优良承载性能的获得。结论极限载荷与支腿壁厚和拔模角度具有很好的线性拟合优度,可通过壁厚或拔模角度预测支腿结构的极限承载。     

基于混合网格方法的VARTM工艺充模仿真与实验验证

针对VARTM工艺的特点,建立了充模过程树脂流动和预成型体变形行为数学模型。提出了基于混合网格方法的VARTM充模仿真算法,在该算法中,模具型腔几何模型进行二维或三维网格划分,在每个真空袋表面单元上增加一个一维附属单元,用于在仿真过程中实时地吸收或挤出因真空袋变形而产生的局部树脂体积变化,形成混合网格仿真模型;求解过程中,对树脂流动和预成型体变形分别进行求解后,基于上述混合网格模型进行两者耦合操作,实现了仿真精度和速度的统一。搭建了VARTM充模实验平台,进行了一维充模实验,通过仿真结果与实验测量结果对比,验证了本文算法的正确性。最后,通过三维仿真算例,验证了算法对三维复杂结构和顺序浇口策略仿真的可行性。     

大尺寸纤维复合材料箱体零拔模斜度缠绕成型模具设计

以某型发射箱复合材料箱体为应用对象,探讨了一种零拔模斜度组合式缠绕成型模具的设计,用于大尺寸薄壁结构矩形截面复合材料箱体构件的缠绕成型,以满足长度方向近零拔模斜度的要求。     

模面为圆的平面变形拔制上界理论解

本文对模面为圆的平面变形拔制问题设定了直角坐标系连续速度场。然后采用变上限积分与参变量积分方法得到了上界解析解。     

盲信道均衡的动量恒模算法

介绍了盲信道均衡恒模算法（CMA）的基本原理，对恒模算法的缺点进行了分析，通过修正恒模算法的迭代公式提出一种动量恒模算法（MCMA）。利用QPSK信号，采用计算机仿真的方法对动量恒模算法与恒模算法进行盲均衡性能比较，模拟结果显示，MCMA算法比CMA算法在收敛速率、降低稳态均方误差和符号间干扰具有明显的优势，有效地改进了信道均衡性能。     

模基水声信号处理技术的研究现状和展望

常规信号处理方法的前提条件相对简单,不能满足水声信号处理中海洋环境非平稳和极低信噪比等实际情况。基于模型的信号处理方法(模基处理技术)能够将物理模型引入到信号处理算法中,并且能够有效利用先验信息提高信号处理的性能,是一种有潜力的信号处理技术。结合多年的模基水声信号处理研究基础,首先介绍了模基处理的基本概念,然后介绍了模基处理器的基本框架和其主要优势,进而对模基技术在水声信号处理各个应用领域的研究现状做了全面的归纳和简要的评述,在此基础上,分析了该领域进一步的研究方向。     

A locally anisotropic fluid–structure interaction remeshing strategy for thin structures with application to a hinged rigid leaflet

An immersed finite element fluid–structure interaction algorithm with an anisotropic remeshing strategy for thin rigid structures is presented in two dimensions. One specific feature of the algorithm consists of remeshing only the fluid elements that are cut by the solid such that they fit the solid geometry. This approach allows to keep the initial (given) fluid mesh during the entire simulation while remeshing is performed locally. Furthermore, constraints between the fluid and the solid may be directly enforced with both an essential treatment and elements allowing the stress to be discontinuous across the structure. Remeshed elements may be strongly anisotropic. Classical interpolation schemes – inf–sup stable on isotropic meshes – may be unstable on anisotropic ones. We specifically focus on a proper finite element pair choice. As for the time advancing of the fluid–structure interaction solver, we perform a geometrical linearization with a sequential solution of fluid and structure in a backward Euler framework. Using the proposed methodology, we extensively address the motion of a hinged rigid leaflet. Numerical tests demonstrate that some finite element pairs are inf–sup unstable with our algorithm, in particular with a discontinuous pressure. Copyright © 2015 John Wiley & Sons, Ltd.     

Numerical Calculation of the Interaction of Superfluid Vortices and a Rigid Sphere

We implement a method for the calculation of the effects of a solid sphere on the dynamics of superfluid vortices. We present in detail the derivation of the mathematical formulae used in a computational algorithm which avoids numerical singularities, as well as an adaptive algorithm for convergence tests and diagnostics of the method’s accuracy.     

Adaptive finite element approximation of multiphysics problems: A fluid–structure interaction model problem

In this paper we consider finite element simulation of the mechanical response of an elastic solid immersed into a viscous incompressible fluid flow. For simplicity, we assume that the mechanics of the solid is governed by linear elasticity and the motion of the fluid by the Stokes equation. For this one‐way coupled multiphysics problem we derive an a posteriori error estimate using duality techniques. Based on the estimate we propose an adaptive algorithm that automatically constructs a suitable mesh for the fluid and solid computational domains given a specific goal quantity for the elastic problem. Copyright © 2010 John Wiley & Sons, Ltd.     

基于ISO13584标准的螺纹实体模型的实现

螺纹是许多标准件中的主要结构,因此螺纹实体模型的实现便成了开发标准件库的重要问题之一。文中依据ISO13584标准,以UG为CAD平台,提出了一个交互式的,采用三维曲面构造参数化螺纹模型的算法。阐述了三维螺纹实体模型的实现原理,开发了数据接口,实现了几何图形文件到UGGRIP语句的映射,并举例介绍了螺纹模型的GRIP程序。     

基于回归算法的印刷品最佳实地密度研究

目的从相对反差最大时密度最佳的角度出发,结合网点扩大,构建基于回归算法的数学模型,确定最佳的实地密度,从而提高印刷品的质量。方法获取过版样张,根据测量的实地密度、相对反差和网点扩大值作出三维坐标图,并基于回归算法建立相对反差K、网点扩大与实地密度函数关系的数学模型;利用该模型找到相对反差最大时,网点扩大和实地密度的参数匹配算法;网点扩大在国标范围(15%~20%)内,最终以方差最小原则确定最佳的实地密度。结果基于回归算法找到了当相对反差最大时实地密度和网点扩大的参数匹配符合函数y=ax+b,确定了C,M,Y,BK油墨的最佳实地密度分别为1.551,1.612,0.975,1.828。结论基于回归算法确定最佳实地密度的方法能够保证相对反差良好,网点扩大适宜,提高了印刷品的清晰度和鲜艳程度,对印刷的质量控制具有一定的指导意义。     

An algorithm for modelling the interaction of a flexible rod with a two‐dimensional high‐speed flow

We present an algorithm for modelling coupled dynamic interactions of a very thin flexible structure immersed in a high‐speed flow. The modelling approach is based on combining an Eulerian finite volume formulation for the fluid flow and a Lagrangian large‐deformation formulation for the dynamic response of the structure. The coupling between the fluid and the solid response is achieved via an approach based on extrapolation and velocity reconstruction inspired in the Ghost Fluid Method. The algorithm presented does not assume the existence of a region exterior to the fluid domain as it was previously proposed and, thus, enables the consideration of very thin open boundaries and structures where the flow may be relevant on both sides of the interface. We demonstrate the accuracy of the method and its ability to describe disparate flow conditions across a fixed thin rigid interface without pollution of the flow field across the solid interface by comparing with analytical solutions of compressible flows. We also demonstrate the versatility and robustness of the method in a complex fluid–structure interaction problem corresponding to the transient supersonic flow past a highly flexible structure. Copyright © 2005 John Wiley & Sons, Ltd.     

A branch and bound algorithm for the strip packing problem

We propose a new branch and bound algorithm for the two dimensional strip packing problem, in which a given set of rectangular pieces have to be packed into a strip of given width and infinite length so as to minimize the required height of the packing. We develop lower bounds based on integer formulations of relaxations of the problem as well as new bounds based on geometric considerations, and reduce the tree search with some dominance criteria. An extensive computational study shows the relative efficiency of the bounds and the good performance of the exact algorithm.     

Generic Asymptotic Expansions

We give an expansion algorithm for germs of exp-log functions at infinity which is correct modulo Schanuels conjecture. We also show how the algorithm can be made generic. More precisely, we reduce the expansion algorithm for exp-log functions depending on parameters to the problem of deciding whether a given system of exp-log equations and inequalities in several variables admits a solution.     

Extracting alternative machining features: An algorithmic approach

Automated recognition of features from CAD models has been attempted for a wide range of application domains. In this article we address the problem of representing and recognizing a complete class of features in alternative interpretation for a given design.We present a methodology for recognizing a class of machinable features and addressing the computational problems posed by the existence of feature-based alternatives. Our approach addresses a class of volumetric features that describe material removal volumes made by operations on three-axis vertical machining centers, including drilling, pocket-milling, slot-milling, face-milling, chamfering, filleting, and blended surfaces.This approach recognizes intersecting features and is complete over all features in our class; i.e., for any given part, the algorithm produces a set containing all features in our class that correspond to possible operations for machining that part. This property is of particular significance in applications where consideration of different manufacturing alternatives is crucial.This approach employs a class of machinable features expressible as MRSEVs (a STEP-based library of machining features). An example of this methodology has been implemented using the ACIS solid modeler and the National Institute's of Health C++ class library.     

Classification and general derivation of interfacial forces, acting on phases, situated in the bulk, or at the interface of other phases

In the present paper the general equation and algorithm to derive interfacial forces, acting on phases, situated in the bulk, or at the interface of other phases are given. Based on that, interfacial forces are classified into the following six major types: (i) the “curvature induced interfacial force” (due to Laplace), (ii) the “interfacial gradient force”, acting on particles in inhomogeneous fluid phases, due to composition-, temperature- and electrical potential gradient (known as Marangoni force, or thermocapillary force), (iii) the “interfacial capillary force”, acting on a phase at an interface of two large phases, including the behaviour of solid particles at the liquid/gas, fluid/fluid and solid/solid interfaces (known as the capillary force, and as the Zener pinning force), (iv) the “interfacial meniscus force,” acting between two, solid phases, situated at a curved fluid/fluid or solid/solid interface, the curvature being due to the gravitational or electric fields (known also as the lateral capillary force, or electrodipping force), (v) the “liquid bridge induced interfacial force,” acting between two, solid particles, due to the liquid bridge of small volume between them, and (vi) the “interfacial adhesion force,” acting between two particles in a homogeneous fluid phase (with the phenomenological Derjaguin- and Hamaker constants, re-visited).