Lattice design and optimization of the SSRF storage ring with super-bends

In the near future,the Phase-Ⅱ beamline project of Shanghai Synchrotron Radiation Facility(SSRF)will be implemented and some dipoles in the storage ring will be replaced by high field dipoles(super-bend),so as to leave room for short straight sections.In this way,the brightness of the hard x-ray emitted from the super-bends can be enhanced,and more insertion devices can be installed.In this paper,super-bends of two lengths are discussed and the corresponding lattices are presented.

Shape design of the reinforcement for bending load-carrying capacity of under-matched butt joint under four-point bending load

To improve the bending load-carrying capacity （ BLCC） of under-matched butt joint under four-point bending load in the elastic stage, the shape design of the reinforcement is studied based on the theoretics of mechanics of materials. The concept, criterion, realization condition and design proposal of equal bending load-carrying capacity （EBLCC） are put forward. The theoretical analysis results have been verified by the finite element method. The simulation results are coincident basically with the ones of theoretical analysis. The research results show that the shape design of the reinforcement of EBLCC can improve BLCC of under-matched butt joint and the unilateral-side type reinforcement can replace double-side symmetry

Engineering Structure and Strength Design of Reducer Bend under Internal Pressure

Standard reducer bends have structural functions of both bend and reducer pipe at the same time. However, there is a lack of strength design method in the current codes. In order to develop the strength design method of the reducer bends subjected to internal pressure, analytical formulas are re-examined. Finite element analysis and stress measurements of the reducer bend are carried out. It is found that it is not appropriate to analyze the reducer bends by using thin membrane theory. The formula derived directly from circumferential stress formula of reducer bends under internal pressure is conservative, which is further verified by the finite element analysis results and it can thus be applied to piping design.

AXISYMMETRIC BENDING OF TWO-DIRECTIONAL FUNCTIONALLY GRADED CIRCULAR AND ANNULAR PLATES

Assuming the material properties varying with an exponential law both in the thick- ness and radial directions, axisymmetric bending of two-directional functionally graded circular and annular plates is studied using the semi-analytical numerical method in this paper. The deflections and stresses of the plates are presented. Numerical results show the well accuracy and convergence of the method. Compared with the finite element method, the semi-analytical nu- merical method is with great advantage in the computational efficiency. Moreover, study on ax- isymmetric bending of two-directional functionally graded annular plate shows that such plates have better performance than those made of isotropic homogeneous materials or one-directional functionally graded materials. Two-directional functionally graded material is a potential alternative to the one-directional functionally graded material. And the integrated design of materials and structures can really be achieved in two-directional functionally graded materials.

Precise Design and Stress Analysis of Straight Conical Gear

Variable section sweeping with sphere involutes is used to generate the precise model of tooth profile. The contact and bending stress of a straight conical gear set with static bearing contact during a meshing cycle is studied using finite element method. Numerical results and comments are presented, revealing that the edge contact causes stress concentration and the gear tooth profile needs further modification.

柔性立管限弯器高效设计方法

目的考虑聚氨酯材料非线性的影响,建立一种简单高效的柔性立管限弯器设计方法。方法首先确定限弯器的初始尺寸,在此基础上进行参数分析,并根据分析结果绘制设计图谱,然后通过插值获得最佳的设计尺寸。结果针对深水与浅水2种典型环境,分别采用本方法与基于遗传算法的优化设计方法进行限弯器设计,通过结果对比验证了方法的有效性。同时发现,深水环境条件设计出的限弯器相对短粗,而浅水条件设计出的限弯器则较为细长,且考虑材料非线性后,2种环境下限弯器的设计尺寸均有所减小。结论本文建立的限弯器设计方法具有广泛的适用性,且能够在确保得到理想设计方案的前提下,显著提高设计效率。与基于遗传算法的优化设计方法相比,采用线性材料和考虑材料非线性时的设计效率可分别提高约10倍和20倍。

高速钢桶焊缝机电机座支撑脚复合模设计

针对高速钢桶焊缝机电机座支撑脚使用2 mm厚的SECC板料进行中小批量冲压成形的要求,设计了3副模具用于制件的4道工序成形。冲孔落料和修边压印采用倒装式复合模结构、切分模和弯曲模采用正装结构,且切分模和弯曲模集成在1副模具内。弯曲模中设计了凸模驱动的双滑块内收弯曲成形机构,该机构在制件弯曲壁的两侧都使用滑块进行夹紧驱动弯曲,能有效防止弯曲回弹,保证了制件的弯曲成形尺寸。模具结构简单实用,成形工艺设计合理,实现了制件的自动化生产。

基于能力保护的新型拉压双向限位装置设计方法研究

为保护通航渡槽结构缝之间止水不被破坏,提出替代止水受力的新型拉压双向限位装置.此装置力学特征类似销轴耳板连接结构,此类结构有多重破坏模式的弱点.为克服此弱点,结合《钢结构设计标准》(GB 50017—2017)中销轴耳板连接结构设计方法,在该装置的静力设计中,基于能力保护的设计思想提出了以单一销轴弯曲破坏为该装置破坏模式的设计方法.基于实体有限元数值模拟,分析了加载过程中此装置整体与各部件的受力-变形曲线特点.结果表明:以外荷载-整体变形量曲线不出现塑性特征为依据,判定装置的静力承载力大于设计外荷载、设计方法偏于安全;通过销轴的外荷载-弯曲变形量曲线与限位装置的外荷载-整体变形量曲线显现的非线性特征相一致以及板的外荷载-整体变形量曲线在加载过程中基本保持线性状态,说明板是被保护构件、装置破坏模式为单一的销轴弯曲破坏.研究结果表明此设计方法现实可行.

Optimization of Energy Density in Girders under Pure Bending with an Extruded Monolithic Cross-Section

This article proposes use of extruded compound materials with optimized resistant cross-sections as an alternative, in this case, seeking the maximum energy density as a design criterion. The advantage of this proposal is that it extends the life cycle and decreases fatigue issues.

大跨度装配式单层网壳十字形半刚性螺栓连接节点抗弯性能研究

装配式连接节点是大跨度装配式单层空间网壳结构体系的关键。提出一种适用于大跨度单层网壳结构的十字形板装配式节点。该节点由圆钢管、十字形钢板、角钢、矩形连接盖板、圆盖板和高强螺栓组成,其中圆钢管、盖板、十字形钢板在工厂焊接,现场将十字形板和角钢、矩形盖板用高强螺栓连接。该节点通过设置角钢、矩形连接盖板和十字形钢板螺栓连接,在节点受到弯曲荷载时,角钢和矩形连接盖板可以首先承受弯曲荷载,从而减少节点内侧的十字形钢板塑性损伤,并且提高节点的抗弯性能。利用有限元模拟方法,构建新型连接节点有限元模型,分析了十字形钢板和角钢厚度等变量如何影响节点在平面内外的抗弯性能。通过对各组成部分尺寸的参数化研究,得到了这些因素对所提出的连接节点平面内外抗弯性能的影响规律。研究结果表明,采用角钢与矩形盖板相连接形成的十字形节点,在抗弯刚度和承载力方面表现出了优异的性能。通过调节十字形板厚度、螺栓个数、角钢和盖板厚度可调控节点的初始抗弯刚度和抗弯承载力。基于刚性节点设计方法,对该半刚性节点进行尺寸理论设计,结果表明该方法可以保证节点弯矩设计值基本达到圆钢管的屈服弯矩,满足设计要求,提高节点安全。

Evaluation of Contact Pressure in Bending under Tension Test by a Pressure Sensitive Film

The contact pressure acting on the sheet/tools interface has been studied because of growing the concern about the wear of tools. Recent studies make use of numerical simulation software to evaluate and correlate this pressure with the friction and wear generated. Since there are many studies that determine the coefficient of friction in sheet metal forming by bending under tension (BUT) test, the contact pressure between the pin and the sheet was measured using a film that has the ability to record the applied pressure. The vertical force applied to pin was also measured. The results indicate that the vertical force is more accurate to set the contact pressure that using equations predetermined. It was also observed that the contact area between the sheet and the pin is always smaller than the area calculated geometrically. The friction coefficient was determined for the BUT test through several equations proposed by various authors in order to check if there is much variation between the results. It was observed that the friction coefficient showed little variation for each equation, and each one can be used. The material used was the commercially pure aluminum, alloy Al1100.

新型滚轮弯曲工艺的回弹研究

传统板材回弹研究以V型或U型弯曲为对象,其成形精度较低、回弹补偿控制困难。针对以上问题,基于“弯曲中曲率恒定”思想,提出了新型滚轮弯曲工艺,并设计了相应的折弯装备。以DP590高强钢和Al6061-T6铝合金为对象,研究了R/t=5时弯曲角度及偏置距离对回弹的影响,对比了回弹角的试验值与理论解析值。结果表明:随偏置距离的减小,回弹角增大,板材应变更均匀;随弯曲角的增大,回弹角增大,增长趋势近似指数函数与幂函数的组合。表明新型滚轮弯曲工艺的回弹规律明显,具有高效、精确补偿回弹的能力与抑制折弯损伤、增加成形均匀性的潜质。

景观用的偏高岭土-地聚物纤维材料制备及性能

针对传统园林景观造型材料耐久性差的问题,制备一种偏高岭土-地聚物纤维材料,并对制备材料的性能进行研究。结果表明,偏高岭土-地聚物纤维材料的最佳配比为m(水)∶m(胶材料)=0.35、w(纤维)=12%、水玻璃模数1.95、w(偏高岭土)=16%;该条件下制备的地聚物材料养护时间从10 d增至60 d,静曲强度从8.3 MPa降至6.5 MPa;经过冻融处理后,偏高岭土-地聚物静曲强度从9.8 MPa降至7.0 MPa,静曲强度损失率约为28.8%,内结合强度为1.1 MPa,握螺钉力强度为1.854 kN,吸水厚度膨胀率为1.28%,浸水后静曲强度为8.2 MPa;改性的地聚物纤维材料各项性能均符合GB/T 24312—2009标准,可在园林景观中发挥作用。

柔性屏COF弯折结构的正交试验优化设计

OLED(Organic Light-Emitting Diode)屏幕COF(Chip on Film)连接过渡区的金属层在模组弯折阶段和可靠性验证阶段容易发生断裂,导致屏幕显示异常。本文采用试验设计(Design of Experiment,DOE)方法,以弯折成型状态和可靠性状态下的金属层应力最小作为试验指标,以泡棉厚度、泡棉偏移、金属包覆层(Metal Cover Layer,MCL)厚度和U型膜偏移作为影响因子,设计L9(34)正交试验方案,使用有限元方法对9组试验方案进行数值模拟和分析,并进行弯折成型和可靠性状态下的试验验证,最终获得了最优组合方案。有限元方法和试验结果表明,U型膜贴附偏移量对COF区的金属层弯折应力的影响最大,其次是泡棉厚度,再次是MCL厚度和泡棉贴附偏移量。最优组合方案在弯折成型和可靠性状态下皆具有最小的金属层应力,其值分别为57 MPa和523 MPa。最优组合方案的弯折成型和可靠性试验达到了100%的产品良品率,满足设计和生产要求。

一种具有弯曲平移特性的2T1R并联机构设计与位置分析

基于方位特征(Position and Orientation Characteristic,POC)集方程的并联机构设计理论,设计了一种具有符号式位置正解并且存在部分运动解耦特性的两平移一转动(2T1R)并联机构。对该机构进行了方位特征集、自由度以及耦合度等拓扑性能的分析;基于拓扑结构运动学建模原理,求解了该机构的解析式位置正解、解析式逆解,并通过位置逆解进行了验算,证明了该机构具有弯曲平移的运动特性。传统的只有平直运动的2T1R并联机构要实现曲线平移,需要将多个平直移动通过复杂算法进行曲线拟合,而该机构只需通过一维弯曲平移即可实现,极大降低了机构的复杂程度及控制算法的难度。

可重塑CFRP加强筋壁板模压塑形模具设计与仿真分析

介绍了一种碳纤维增强Vitrimer树脂基复合材料T形加强筋壁板热弯塑形模具设计与制造过程,从T形加强筋壁板外形尺寸、模具设计、温度场和热变形校核等方面阐述了T形加强筋壁板的热弯塑形过程,并辅以试验和生产实践介绍了Vitrimer树脂基复合材料T形加强筋壁板热弯塑形的成型效果,对成型制品的关键尺寸和表观状态进行了检验与评定,均能满足要求。该模具结构的设计可以实现Vitrimer树脂基复合材料制品在热弯塑形模压成型过程中的均匀热传递与高精度成形制造,减少了制品热变形引起的应力集中现象,提高了制品生产效率和成品率。

某轻型客车防撞梁三点弯力学性能CAE分析与实物验证

文章针对某轻型客车的前防撞梁系统三点弯力学性能进行了深入分析,采用计算机辅助工程(CAE)技术基于详细几何建模和材料属性定义,构建了精确的防撞梁有限元模型,详细分析了防撞梁在不同加载条件下的应力分布、塑性变形区域以及能量吸收情况。提出了整车64公里高速碰撞条件下防撞梁本体不发生断裂,分解至防撞梁三点弯力学性能接受标准及防撞梁耐挤压力计算方法,仿真结果表明,防撞梁设计能够有效分散冲击力,减少对车身结构的损害。为了验证仿真结果的有效性,进行了物理三点弯曲试验,将实际测试数据与CAE分析结果进行了对比。实物测试结果显示,实测数据与仿真分析吻合良好,证明了所采用的CAE方法在预测防撞梁的力学性能方面具有高度的可信度,为优化设计和提高轻型客车的被动安全性提供了理论依据和实践指导。

非对称翼缘H型钢组合梁设计的若干关键因素

非对称翼缘H型钢组合梁是一种优化的组合梁形式,可以提高组合梁的截面抗弯效率,减小工程量,降低碳排量。对非对称翼缘H型钢组合梁的最优截面解析解、截面抗弯效率的影响因素、承载力有效性以及抗弯刚度进行研究。根据荷载分布情况可以确定组合梁施工阶段与使用阶段抗弯承载力比值的限值,由此可以得到满足限值的上翼缘厚度百分比区间,此区间内的抗弯承载力最大值点即为设计控制点。根据上述成果提出了全新的非对称翼缘H型钢组合梁截面设计策略。结合实际工程,对组合梁的经济性进行验证,结果表明,非对称翼缘H型钢组合梁的经济效益显著。

铝合金变直径管材旋弯渐进成形规律有限元模拟研究

研究设计了一种用于旋弯渐进成形的双辊柔性弯曲模,其可对管材施加较强周向约束,且成形中可自适应转动。相比传统圆弧型单辊弯曲模,新型双辊柔性弯曲模能够有效降低旋弯渐进成形弯曲力,提高成形稳定性,并抑制管材截面畸变。在此基础上,建立了铝合金管材旋弯渐进成形-回弹全过程有限元模型,并通过与柔性弯曲成形对比,分析获得了旋弯变形耦合对成形结果的影响规律,发现在旋压基础上引入弯曲工步,会引起一定程度的截面变形和壁厚不均匀现象;在弯曲基础上引入旋压工步,会减小弯曲段截面变形量,增加内外脊线壁厚差异,加剧起皱风险,减小成形后的回弹变形。

PHC管桩复合地基失稳分析及加固处治设计

湖南省某高速公路位于洞庭湖平原区,以湖相及河湖相沉积盆地的软土为主,失稳路段采用PHC管桩复合地基处治,当路基填筑到96区时,路基发生失稳滑移。以失稳滑移路段为依托,分析了管桩复合地基失稳的原因,发现了其失稳的破坏模式并非剪切破坏而是弯曲破坏,提出了加固处治设计。通过1.5 a的监测,其数据均已收敛,表明了其加固处治设计是安全可靠的,确保了高速公路如期通车和运营安全。