基于神经网络和遗传算法的光塑性图像处理

本文论述了神经网络、遗传算法结合起来在光塑性图像处理中的应用 ,以楔横轧工序的光塑性图像处理为例 ,三次投射时光塑性图像中各点都有对应的等差线条纹级数和等倾线角度 ,首先利用神经网络建立起图像参数与等效应变之间关系的数学模型 ,然后用遗传算法对图像参数进行优化 ,优化结果与实际情况吻合良好。由此证明神经网络、遗传算法完全可以较好地优化光塑性图像参数 ,并应用于光塑性图像处理领域     

《实验应力分析》 赵清澄、石源主编,科学出版社出版,1987.

本书内容包括电测和光测两大部分。光测部分除常规的光测技术之外,还涉及动光弹、热光弹、光塑性及焦散线法等,并把光测法在断裂力学中和生物力学中的应用作为两个专题     

用光塑性技术求解两种应变定义的应变场

本文提出了用Almansi应变张量进行光塑性三维应变场求解的方法.为了便于工程应用,进一步提出了工程应变求解方法.用所提出的方法在连杆上进行了塑性成形后的变形场研究.     

摆辗成形后的摩托车启动齿轮三维塑性应变场的光塑性分析

本文叙述了采用聚碳酸脂材料模拟低碳钢和低碳合金钢一类金属的摩托车启动齿轮(下面陶称为端面齿轮)摆辗成形过程。运用光塑性法计算分析了氐形后的光塑性模型内部三维塑性应雯分布;对采用螺旋形轨迹和玫瑰线轨迹成形后的光塑性模型内部的三维塑性应变分布进行了分析比较。该方法已为摆辗最佳工艺参数的选择提供了有用的依据。     

理想刚塑性滑移线解中刚性区的校核——板条拉拔的完全解

<正> 1.引言理想刚塑性平面应变问题中的滑移线解法在许多工程实际问题(如金属压力加工、地基分析…)中都有着广泛的应用,在塑性力学教程中也占有比较重要的地位.通过滑移线解法,除了要得到塑性区内的应力和速度分布外,一般还应校核塑性区内各点的塑性功率是否为非负的;校核刚性区内是否存在既满足平衡     

理想刚塑性滑移线解中刚性区的校核——板条拉拔的完全解

1.引言理想刚塑性平面应变问题中的滑移线解法在许多工程实际问题(如金属压力加工、地基分析…)中都有着广泛的应用,在塑性力学教程中也占有比较重要的地位.通过滑移线解法,除了要得到塑性区内的应力和速度分布外,一般还应校核塑性区内各点的塑性功率是否为非负的;校核刚性区内是否存在既满足平衡     

光塑性法基础研究及其应用

光塑性法是基于透明双折射材料受力超过其弹性极限状态时光学图象解释的一种全场方法。本文简要地介绍普通光塑性法的基本原理,对光塑性材料的力学、光学性能进行了测定,并研究聚碳酸酯材料的应变一条纹级数关系,建立了其应变—光学定律,还把本法应用于一个典型例子的研究,获得了满意的结果。     

用光塑性方法确定工程构件的疲劳裂纹扩展荷载门槛值

提出疲劳裂纹尖端塑性核半径门榄值Ｒｔｈ的概念及计算方法,Ｒｔｈ是材料性质,在满足光塑性相似关系要求及模型与原型几何形状尺寸相同的前提下,模型与原型间的相似系数ｎ为两种材料屈服极限之比。     

基于染料的光弹性涂层方法回顾与展望

光弹性涂层法是最常用的实验应变分析测试技术之一,但其实际应用受到诸如准备时间长、基底加强效应、复杂的数据后期处理等固有局限性的影响。近年来,出现了两种通过在光弹性聚合物材料中添加非发光染料或发光染料的新的光弹性涂层制作方法。这种基于染料的光弹性涂层使新方法能够克服上述传统光弹性涂层法应用中的许多局限性,并有望成为重要的应变测量工具。论文回顾了这两种新的基于染料的光弹性涂层方法的提出与发展过程,分别介绍了两种测量方法的实验装置、基本原理及一些实际应用,总结了两种新方法各自的优点与不足。最后指出了基于添加发光染料的发光光弹性涂层的未来发展方向和技术改进。     

《实验力学》第五卷(1990)分类索引

综述光弹性技术在曲轴设计中的应用,】,1中国电测理论和应用技术发展的十年,2,131动态拉伸及动态循环加载实验技术,2,144电子散斑干涉法和video全息干涉,4,387电阻应变计测纽技术全息千涉术散斑计且光弹塑性法声测皿材料试验实验流体确定应力集中的三应变片测法,2,205检侧表面裂纹开裂点的应变片方法,2,235异弹模界表面裂缝的动态实验研究,3,275预应力钢筋混凝土管口承载力试验研究,3,354扭转力学性能电测技术材料试验研究,3,360混合光载波法分离动静态主应力,2,152全息干涉条纹图的计算机自动处理与识别,3,268缺口根部塑性区和拉应力场对循…     

关于拉压异性模型材料的光塑性原理

本文根据晶体光塑性材料氯化银光力学性能的研究，提出了对于具有拉伸、压缩屈服特性不同的光弹塑性材料所应满足的应力、应变相似转换关系。     

花键轴冷挤压成形后的三维光塑性模拟研究

本文利用光塑性方法,以聚碳酸酯（Ｐｏｌｙｃａｒｂｏｎａｔｅ）为材料研究了矩形花键轴冷挤压成形过程,获得了花键挤压成形的三维塑性应变场分布,提出其变形的应变分布特征,并对典型截面的应变进行了计算分析;文中还通过对聚碳酸酯材料的实验,得到了使花键齿形充满的最佳坯料尺寸,为实际工艺生产优选出合理的工艺参数。     

Loaded and unloaded optical response of polyester model materials

The optical behavior of mixtures of rigid and flexible polyester resins when loaded and unloaded under constant strain-rate and varying test temperature are characterized. New evidence about the photoplastic method of analyzing deformed but unloaded models is presented through experiments with tensile or compressive uniaxial specimens, diametrically compressed disks and beams under pure bending, which were analyzed during loading, unloading and after being unloaded.     

The ductile fracture of polycarbonate

The fracture of a known ductile polymer (polycarbonate) is investigated. It is shown that polycarbonate obeys the Dugdale model of ductile yielding by comparing measured plastic-zone sizes and displacements to the theoretical predictions. Strain-energy release rates are calculated and the critical value is shown to be one or two orders of magnitude higher than critical values for brittle polymers. Photoelastic photographs of the fracture process are presented and it is shown that the photoelastic effect definitely enhances the definition of the yield zone. Microscopic photoelastic photographs are also presented which are used to give a new interpretation to the photoplastic effect. Finally, suggestions for future work are presented.     

Photoplastic stress analysis considering rate effect

The possibilities of cellulose acetate as a photoplastic model material used in the uniaxial tension test were presented by the authors in Ref. 1. Empirical formulas were proposed for photoplastic stress analysis considering the effect of strain rate and temperature. In this paper, the stress-strain-optic laws derived from the uniaxial tension test were confirmed precisely under the biaxial stress field. Consequently, the biaxial stress-strain-optic laws of cellulose acetate can be represented by simply substituting the difference of the principal stress and the difference of the principal strain into the terms of the stress and the strain in the empirical formulas for the uniaxial stress state, respectively. Therefore, the empirical formulas considering the influence of strain rate were obtained for the photo-viscoelastoplastic plane-stress analysis during the usual static loading. This method was applied to an elastoplastic problem of a finite plate with a circular hole under uniaxial tension. The distribution of stress and strain, the stress-concentration factors in the elastoplastic region and the development of the plastic region were obtained experimentally taking the rate effect into account. As a result, the stress on a minimum section in a model increased as head speed increased. On the other hand, the distribution of strain, the development of the plastic region and the stress-concentration factors were almost never influenced by head speed.     

Three-dimensional strain distributions in upset rings by photoplastic simulation

The changes in internal diameter that occur when a hollow disk, or ring, is plastically deformed by axial compression have been proposed as a method for measuring interface friction during metal forming. The adoption of this test method has been delayed because the three-dimensional strains in such rings are not known. This paper describes how an experimental method using photoplastic simulation was used to obtain the three-dimensional strains for a particular ring geometry. It presents proot of highly nonuniform strains and also shows that the division between flow inward and flow outward occurs at different radii through the thickness of the ring.     

New model materials for photoelasticity and photoplasticity

Two new materials are proposed as models for photoelasticity and photoplasticity. One is cast resin fully cured epoxy-phenol alloy which is made by the mutual cross linking of pre-condensed resins of epoxy and phenol. While epoxy-phenol alloy resin is available only for photoelasticity, the other, polycarbonate resin, is useful not only for photoelasticity, but also for photoplasticity. Polycarbonate is very tough and has large values of both photoelastic stress sensitivity and modulus of elasticity. The excellent cold workability of polycarbonate is proved by a deep-drawing test. Hence the photoplastic results obtained from a polycarbonate model can be applied by analogy to the plastic stress analysis in other ductile materials. Both resins are very transparent even in the plastic state.     

Photovisco-elastoplastic behavior of polycarbonate material under creep and tension tests

Polymers are widely used as photomechanical models of a prototype material (often a metal). Photoplasticity is one of the methods used in order to show the behavior of plastic materials stressed beyond the linear elastic limit. To illustrate this process we have analyzed the photovisco-elastoplastic behavior of polycarbonate as a photoplastic material. In this paper a technique for local and simultaneous measurement of birefringence and principal strains is presented. The mechanical and optical properties, at room temperature, have been evaluated by means of uniaxial tension tests. A series of creep tests has been carried out in order to study the photovisco-elastoplastic behavior of polycarbonate. In two different experiments we analyzed nonlinear birefringence and the amplitude of the corresponding strains. We could thus evaluate the distribution of strains and the distribution of uniaxial stress for each birefringence state and vice versa.