Fe-1.6%Si无取向硅钢的热变形与相变规律

采用Gleeble1500型热力试验机对Fe-1.6%Si无取向硅钢进行了热模拟试验,得到了该钢静态和动态CCT曲线以及在不同应变速率和温度下的应力-应变曲线;通过峰值应力与温度变化曲线,得到了相变开始和结束的温度区间。结果表明:随着冷却速率的增大,相变温度降低,动态CCT曲线中的奥氏体向铁素体的转变温度比静态CCT曲线中的高,1 041℃以上为奥氏体区,1 041～955℃为奥氏体和铁素体两相区,955℃以下为铁素体区;建立了该钢在奥氏体区、铁素体区以及奥氏体-铁素体两相区变形抗力的数学模型,该钢的流变应力通常随变形程度和应变速率的增加而增大。     

AerMet100钢热压缩过程流变应力模型

用Gleeble-1500D型试验机研究了AerMet100钢热压缩变形过程流变应力的演变规律.结果表明:流变应力随变形温度的提高而降低,随应变速率和变形量的提高而增加.基于三因子的二次正交回归设计分析方法,建立了流变应力随变形量、应变速率和温度变化的数学模型并对流变应力进行了预测.该模型预测结果与实测结果基本吻合.     

热变形参数对LC4铝合金流变应力的影响

在Gleeble-1500热模拟试验机上,以不同应变、应变速率和变形温度对LC4铝合金进行了高温压缩流变试验,得出了真实应力曲线,并采用神经网络的方法建立了该合金高温变形抗力与应变、应变速率和变形温度对应关系的预测模型。结果表明：变形温度和应变速率的变化强烈地影响合金流变应力的大小,流变应力随变形温度的升高而降低,随应变速率的提高而增大;神经网络能够比较精确地预测材料的流变应力。     

Al-8.4Zn-2.2Mg-2.4Cu合金高温压缩变形的流变应力

在Gleeble-1500热模拟试验机上，采用高温等温压缩试验，研究了Al-8．4Zn-2．2Mg-2．4Cu铝合金在250～450℃温度范围及1．0～0．001s^-1应变速率范围内压缩变形的流变应力变化规律。结果表明，应变速率和变形温度的变化强烈地影响着合金的流变应力，流变应力随变形速率的提高而增大；随变形温度的提高而降低；其流变应力值可用Zener-Hollomon参数来描述。从流变应力、应变速率和温度的相关性，得出了该合金高温变形的四个特征常数。     

基于克里金方法的6013铝合金多道次降温热压缩变形行为建模

为量化分析多道次降温热压缩变形过程中流变应力在加工参数影响下的变化规律,以实现对产品成型过程的合理控制,研究了6013铝合金的多道次降温热压缩变形行为;基于试验数据和克里金方法构建了该变形行为的模型。结果表明:在多道次降温热压缩变形过程中,变形温度对流变应力具有显著影响,流变应力随着变形温度的降低呈台阶状升高;基于克里金方法构建的多道次降温热压缩变形行为模型具有较高的预测精度与稳定性,能够很好地描述多道次热压缩变形过程。     

α+β两相区压缩变形后TC21合金的显微组织模拟

使用Gleeble-3500型热模拟试验机对轧制态TC21合金在α+β两相区进行压缩变形试验,研究了合金在不同热变形温度(870～960℃)、不同应变速率(0.001～1 s-1)条件下的组织和流变应力曲线,建立了流变应力本构方程和动态再结晶位错密度模型,并进行了显微组织模拟及验证.结果表明:合金的流变应力曲线呈现的软...     

HG700汽车大梁钢的热变形行为及 流变应力本构模型的建立

采用Gleeble 3500型热模拟试验机对HG700汽车大梁钢进行单道次压缩试验,研究了其在变形温度950～1 150℃和应变速率0.01～5.00s~(-1)条件下的流变应力行为;根据真应力-真应变曲线,采用线性回归方法建立该钢的流变应力本构模型,并进行了试验验证。结果表明:在高应变速率(1.00,5.00s~(-1))下,HG700汽车大梁钢的动态软化行为以动态回复为主,而在低应变速率(0.01,0.10s~(-1))下,HG700汽车大梁钢发生了明显的动态再结晶;变形温度的升高及应变速率的降低均会促进流变应力的降低,且会促进应力更早达到峰值;由构建的以变形温度、应变速率、真应变为变量的流变应力本构模型得到的预测结果与试验结果吻合良好,该模型可准确地预测HG700汽车大梁钢的流变应力。     

AZ31变形镁合金等温变形力学特性的研究

针对AZ31镁合金,采用Gleeble1500热模拟试验机对其在不同温度和变形速率下的流变应力进行了实验研究,结果表明镁合金在进行高温压缩的情况下,变形温度和应变速率对流变应力有显著的影响,流变应力随应变速率的升高和变形温度的降低而升高。在此基础上,建立了流变应力的数学模型,其结果为镁合金的塑性成形工艺的制订提供理论依据。     

Fe-3.0%Si-0.09%Nb取向硅钢的高温流变应力

通过热模拟试验机测定了Fe-3.0%Si-0.09%Nb取向硅钢在不同变形温度和应变速率下的真应力-真应变曲线,分析了变形参数对流变应力的影响规律,通过线性回归分析计算出该取向硅钢的热变形应力指数n以及变形激活能Q,并构建了流变应力本构方程。结果表明:该取向硅钢的真应力-真应变曲线为动态回复型,其变形时的流变应力主要取决于变形温度和应变速率;当应变速率一定时,流变应力随着变形温度的升高而减小;变形温度一定时,流变应力随着应变速率的增大而增大;用构建的Fe-3.0%Si-0.09%Nb取向硅钢流变应力本构方程计算得到的流变应力与通过试验测得的结果相吻合。     

低碳钢热轧过程中组织变化的研究

用宝钢SS400钢，在Gleeble 1500热模拟试验机上进行了3道次及6道次降温变形试验，每道次变形前和变形后均进行喷水冷却，以研究多道次变形过程的组织变化。为确定应变诱导相变的上限温度，采用变形后落水冷却的方法进行了不同温度下单道次变形试验，测定了不同温度变形后冷却速度为3℃／s时冷却过程的相变点Ar3。通过对多道次和单道次试验的组织分析，结合变形后冷却过程相变点的测量结果，初步确定了900－830℃温度范围内轧制过程的组织变化。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

Fifth International Summer School on Screw-Theory Based Methods in Robotics

正3-11 September,2014University of Bologna,Bologna,Italy www.summerscrews.org summerscrews2014.ing.unibo.it SUMMER 20SCREWS 14In 2014,our screw-theory school comes to the world's oldest university.In early September,Summer Screws'14 will gather six experts in the application of screw theory in robotics and up to 40 participants at the University of Bologna,Bologna,Italy.The school will teach attendees how to apply existing methods and empower them to develop new ones in their own research.The basic theoretical notions will be introduced in a rigorous manner,emphasizing examples,applications,and exercises.Scholarships are available.     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

INDUSTRIAL ENGINEERING AND VISUALISATION-A PRODUCT DEVELOPMENT PERSPECTIVE

Taking the actual project of teaching and researching process for example, the relationship between the industrial engineering and product development is discussed. And use the novel visualization technology to support the industrial engineering and product development. How to use the new computer modeling and simulating technologies to support the product development and industrial engineering, is introduced especially. The support includes both domestic products and industrial systems. The visualization and computer technologies take a very important role in some system or multi-direction modeling, those technologies mentioned above can help the industrial engineers study the effect of design on the whole life circle, including the producing steps. So the engineers can avoid making the wrong decision which may cause bad effects on the whole industrial engineering.     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...