Spectral element analysis for an axially moving viscoelastic beam

In this paper, a spectral element model is derived for the axially moving viscoelastic beams subject to axial tension. The viscoelastic material is represented in a general form by using the one-dimensional constitutive equation of hereditary integral type. The high accuracy of the present spectral element model is verified first by comparing the eigenvalues obtained by the present spectral element model with those obtained by using the conventional finite element model as well as with the exact analytical solutions. The effects of viscoelasticity and moving speed on the dynamics of moving beams are then numerically investigated.     

基于数据点正投影和曲面法矢的自由曲面造型

提出用控制自由曲面形状的数据点投影和曲面在数据点的法矢进行自由曲面造型的新思想。利用数据点的正投影 (二维坐标 )和曲面法线方向计算出数据点的三维坐标后 ,即可采用现有的自由曲面造型方法 ,如采用参数双三次样条曲面等自由曲面造型方法构造自由曲面。这种给定自由曲面数据的方法具有易于控制自由曲面形状、几何意义明显等优点     

FINITE DIFFERENCE METHOD-BASED SIMULATION OF TEMPERATURE FIELDS FOR APPLICATION TO ORTHOGONAL CUTTING WITH COATED TOOLS

ABSTRACT

A finite difference method was proposed to model the effect of a variety of tool coatings on the magnitude and distribution of temperatures through the tool-chip contact region and the coating/substrate boundaries. For each workpiece-tool pair tested the intensity of uniformly distributed heat flux and relevant analytically obtained values of the heat partition coefficient were assumed to change with variations of cutting speed and the corresponding friction. In this case the simulation of an orthogonal machining of AISI 1045 steel was performed using special computing algorithm with elementary balances of induced energies (MBE). It is concluded that the temperature contours obtained reflect favorable the specific contact conditions existing at the tool-chip interface and substantial differences can arise from coating effects.     

中小企业实施敏捷制造的模式探讨

在吸收现代企业管理思想的基础上，提出了一种面向中小企业群体实施敏捷制造的新模式。该模式由经营管理系统、权利决策系统和联盟监督机构3部分构成，以提高企业组织管理敏捷性为突破口，体现了“渐进式”的敏捷化改造原则，容易实施，也较容易为现有中小企业所接受。     

基于漏斗模型和分布合作理论的生产计划控制系统

本文提出了一种基于漏斗模型和分布合作理论的生产计划控制系统，讨论了一些重要的概念和技术，如漏斗模型、分布合作方式和虚拟加工单元。实践表明，生产计划的有效性和灵活性是这一系统的显著优点     

Numerical analysis of welding residual stress using heat source models for the multi-pass weldment

Numerical prediction of welding-induced residual stresses using the finite element method has been a common practice in the development or refinement of welded product designs. Various researchers have studied several thermal models associated with the welding process. Among these thermal models, ramp heat input and double-ellipsoid moving source have been investigated. These heat-source models predict the temperature fields and history with or without accuracy. However, these models can predict the thermal characteristics of the welding process that influence the formation of the inherent plastic strains, which ultimately determines the final state of residual stresses in the weldment. The magnitude and distribution of residual stresses are compared. Although the two models predict similar magnitude of the longitudinal stress, the double-ellipsoid moving source model predicts wider tensile stress zones than the other one. And, both the ramp heating and moving source models predict the stress results in reasonable agreement with the experimental data.     

位图矢量化在模型制作中的应用

这里简单介绍了位图矢量化的概念。通过矢量化，将图像文件转换位CAM软件可以识别的图形文件，然后生成NC程序并在数控机床上加工出模型。     

旋耕机运动参数的优化设计方法

首先分析了旋耕机单位体积功耗数学模型，根据数学模型的特点，提出用广义最小二乘法确定目标函数和用最速下降法优化运动参数，为旋耕机总体参数的优化设计提供了可靠的计算模型。     

磨料浆体射流切割机床中切割质量研究

介绍了磨料射流切割机床的组成和工作原理。分析了射流切割表面质量的影响因素，并在此基础上建立了切割表面波纹度模型。初步讨论了质量控制方法。     

反求设计中非接触式位移检测的研究与应用

论述了反求设计中非接触式位移检测的基本原理,特别是对其检测的精度进行了详尽的分析,并基于此构建了一套测控系统,系统在非接触式位移检测中有较好的位移采样能力。