柔性薄管板换热器的结构分析与优化

运用ANSYS对采用柔性薄管板的换热器建立了热分析与结构分析的有限元模型,分析了柔性薄管板的温度场及应力场,得出了管板上的应力分布及最大应力发生部位。根据应力分析结果对影响管板应力的主要结构参数如管板厚度、换热管中心距、不布管区宽度、管板与壳体连接处的转角结构和转角半径进行了分析优化,得到了较合理的设计结果。     

基于ANSYS的双管板换热器管板厚度设计探讨

由于双管板换热器管板结构的多样性,其管板厚度设计方法目前国内没有标准可依。针对某U型管及固定管壳式换热器双管板结构,根据SW6软件相应模块进行管板厚度近似计算,在此基础上采用ANSYS软件对管板结构进行热应力分析和优化设计,进一步讨论了聚液壳结构的影响。分析结果表明,双管板换热器管板厚度采用SW6软件近似计算是安全的,但结果过于保守。有限元优化设计有效地降低了管板厚度,为双管板换热器管板设计提供了有效手段。     

换热器板翅结构数值模拟及强度设计准则修正

传统的紧凑型换热器设计中隔板与翅片的强度设计准则的不合理性在于过于保守,使得计算厚度值偏大.通过全参数化的有限元数值模拟,获得了一系列数据,分析了翅片和隔板中应力与结构参数的关系,结果表明翅片和隔板中应力值较原经验公式的计算值小,尤其是隔板中的应力与原公式的规律也存在明显差别.利用数据拟合技术,获得了翅片和隔板应力新的工程计算表达式,是对现有板翅结构设计规范的有效补充.     

有关管板厚度的取值问题

管板是管壳式换热器最重要的受压元件之一,管板的合理设计对降低设备费用和保证设备安全运行是至关重要的,管板的强度计算又是管板合理设计中很关键的一步。为此,应正确理解管板名义厚度、管板有效厚度和管板最小厚度的取值问题。     

大直径挠性薄管板合成反应器的有限元分析

采用GB 150、SH/T 3158、西德AD以及GB/T 151标准中的方法对大直径挠性薄管板进行了计算,确定了管板的初始名义厚度。基于ANSYS软件中的APDL语言建立了不同管板厚度的热分析与结构分析的有限元模型,分别对其在6种不同工况下的应力进行了热-结构耦合分析,采用JB 4732,GB/T 151标准分别对结构应力与换热管稳定性和拉脱力进行了强度评定,同时也分析了管板的位移量,最终确定了管板合适的名义厚度。计算结果表明,管板边缘区应力值较大,从边缘到布管区中心呈波动衰减趋势;管板过渡段起着协调管束与管板的变形作用,该区域的弯曲应力值较大。模拟结果可为该类挠性薄管板的设计提供一定参考依据。     

大型丁醛转化器管板的轻量化设计

通过有限元方法对丁醛转化器在不同类型单个载荷作用下,管板及与其连接部件的应力随管板厚度的变化规律进行了研究,并由此确定了管板的初步设计厚度,最后在各种载荷组合工况下对管板进行校核,确定最终设计厚度。此管板厚度与目前已投产的国产化产品相比较减小了一半以上,实现了丁醛转化器管板的轻量化设计。     

浮头式,填函式换热器管板设计方法的改进

在以往的浮头式和填函式换热器管板的应力分析研究中,都假设管板边缘简支或固支。本文考虑了管板边缘的各种真实支承情况,提供了浮头式和填函式换热器管板改进的设计方法。在某些情况下,由该方法所设计出的管板厚度将小于按GB—151的设计厚度。     

基于ANSYS的挠性薄管板设计方法与结构尺寸研究

结合具体算例,采用各国挠性薄管板设计方法进行设计,对比其计算结果,指出各设计方法优缺点。运用有限元Ansys软件进行分析,探讨影响挠性薄管板应力分布特征的主要参数,如挠性薄管板厚度、换热管中心距以及过渡圆角半径,最终得出合理的结构尺寸。     

固定管板换热器N型管箱应力评定方法

当固定管板换热器采用N型管箱结构时,采用SW6. 0中的JB 4732算法可以计算校核筒体或管箱端部的总应力,但有时会出现压力载荷单独作用下筒体或管箱端部的总应力校核不通过的情况,导致筒体或管箱端部厚度比按照GB/T 151设计的更厚。根据一次结构法原理分析表明JB 4732算法存在着保守性,为此介绍了一次结构法和ASME管板设计方法,发现ASME管板设计方法与一次结构法是一致的,由ASME管板设计方法可以得到3种管板一次结构,而JB 4732算法采用的只是第1种一次结构。将这3种管板一次结构用在某换热器的有限元分析设计中,得到了不同的评价结果,选择其中最经济的设计方案,避免了筒体或管箱端部保守的设计。可为换热器结构优化设计提供一定的参考。     

加筋平托盘均布载荷作用下的变形研究

根据板的小变形理论,对平托盘次要结构进行简化,将加筋平托盘面板看成厚度变化的加筋平板,利用在均布载荷条件下板的变形公式,解出了此时的加筋板变形挠度解,并通过改变加筋板各几何参数,得到了加筋板不同的刚度分布,进而分析对最大变形的影响。研究表明,加筋板各几何参数在不同的取值范围对板的最大变形贡献有差异。为筋的厚度与面板厚度之间尺寸的协调设计提供了依据,对平托盘在结构尺寸的初期设计,如何分布配置材料具有一定的实际指导意义。     

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...