Three-dimensional rigid–plastic finite element analysis of non-steady-state shaped drawing process

In this paper, non-steady-state shaped drawing processes have been investigated by using the three-dimensional rigid–plastic finite element (FE) method. In order to analyze the shaped drawing process, a method to define a straight converging die by considering a straight die part, a die radius part and a bearing part has been proposed. In addition, the modeling of the initial billet and the generation procedure of the mesh system have been suggested. The three-dimensional rigid–plastic FE simulation has been performed for a square sectional drawing process and its validity has been confirmed by comparison with existing experimental results. Under the same process conditions, the effect of perimeter ratio and drawing stress in the shaped drawing process has been investigated. Also, the effects of process variables, such as the reduction in area and semi-die angle, on drawing stress and corner filling in the drawing process of a square rod from a round bar have been investigated by using the rigid–plastic FE code developed. In order to investigate corner filling, the diagonal ratio is calculated and compared with the results of the FE simulations. Furthermore, limits of the process variables are determined by considering bulging and necking. From the results, an optimal process condition satisfying reasonable corner filling and a minimum value of drawing stress is suggested.     

浅谈CAD在机械行业中的应用

阐述了有关CAD软件、CAD技术的发展与应用     

Festwalzen – eine Technologie für effizienten Leichtbau

Deep Rolling – a technology for efficient lightweight design Deep rolling is a proven method for increasing the fatigue strength of dynamically loaded parts. Although this application has been used for many years, procedures that induce work hardening and residual stresses are not well known. This article concerns both deep rolling and the potential for considering the resultant residual stresses in the design phase of components to achieve efficient lightweight design. In addition, the article includes new research results regarding the numerical modelling of deep rolling.     

用模块排布计算绘图法调串锻焊结构的筒节

在锻焊结构的反应器制造中，需要对有缺陷的筒节长度及排序进行试算调整串动，此工作较为繁琐。本文介绍的“模块排布计算绘图法”可简化试算工作，提高效率。     

板料拉延中的润滑

论述了板料拉延成形时的摩擦、磨损特征和润滑机理 ,探讨了拉延时润滑油的使用问题 ,为生产实际中润滑油的选择提供了理论根据和实用参考。     

How is emergent writing based on drawing? Analyses of children's products and their sorting by children and mothers.

Writing and drawing produced by children 28-53 months old were compared. Israeli and Dutch preschoolers were asked to draw and write, to classify their products as drawing and writing, and to decide what they had drawn or written. Israeli and Dutch mothers classified the products. Scores on a scale for writing composed of graphic, "writing-like," and symbolic schemes showed improvement with age. Recognition of drawings as drawings preceded recognition of writings as writings. Scores on writing and drawing were substantially correlated, even with age partialed out, suggesting (a) that when children start drawing objects referentially, they write by drawing "print" and (b) that progress in object drawing involves progress in drawing print, so that their writing becomes more writing-like. Children unable to communicate meaning by writing spontaneously resort to drawing-like devices, indicating the primacy of drawing as a representational-communicative system. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

针对高职高专设计素描教学的几点思考

设计素描的探索和改革,始于上世纪90年代,成效显著。在国家大力发展高职教育的背景下,针对高职高专的特点,如何去选择与完善现有成果。在当今电脑得以实现逼真模拟绘画性效果的同时,如何积极地去调整设计素描教学的思路。本人试图阐述自己的几点思考与建议。     

压料面形状对拉深成形影响的研究

介绍了压料面的曲面特性、设计方法以及压料面形状对拉深成形的影响,讨论了压料技术未来的研究方向和在相关领域的应用展望。     

Experimental Investigation of Grouted Helical Piers for Use in Foundation Rehabilitation

Building rehabilitation is critical for numerous older urban areas, many of which have inadequate foundations to support new demands. Consequently, development of practical methods to strengthen existing foundations is crucial. In engineering practice, both subsurface grouting and helical piers have been widely used to address these issues by strengthening the foundation. If the solid shaft of a typical helical pier is replaced by a hollow shaft, then helical piers provide the ability to deliver grout. It is hypothesized that these grouted helical pier systems could address foundation strengthening needs. This paper presents findings from an exploratory research program where grouting and pier placement tools were developed and tested on the large geotechnical centrifuge at the University of California, Davis. Experimental methods and procedures developed are presented, and observations regarding the formation of grout bulbs under different conditions are analyzed. Physical observation of the test specimens indicates that average grout bulb diameters of 0.6–1.9 times the helix diameter (Dh) are attainable. For similar grout mixes, 20–50% larger grout bulbs can be attained by adding just a modest amount of injection pressure. Future research may use these results to develop load performance data.     

回转窑砌砖设计图

为配合我国GB／T17912－1999《回转窑用耐火砖形状尺寸》的贯彻执行，导出了双楔形环形砌砖的计算式为直线方程，介绍了计算图的绘制方法及其在砖衬厚度为160mm等大端尺寸回转窑砌砖中的应用。