方盒形带凸缘件的板料形状优化设计

本文用大变形刚塑性有限元模拟正方形板料在方冲头拉延下的凸缘变形过程，并以所获得的工件形状与金属流动方向为依据，对初始板料形状进行修正。对修正后的坯料形状进行二次模拟，获得了与给定凸缘形状基本吻合的拉延件形状。文中对不同凸缘圆角对极料优化形状的影响作了计算，讨论了在保证边界轮廓位置不变的条件下网格划分的方法。     

The behaviour of pin-ended flange elements in compression

Stowell's solution [1] for the buckling behaviour of flange elements in compression was premised on the assumption that the element was fixed against flexural rotations at the ends, a condition representing relatively thick elements for which the thickness dimension is adequate to prevent rotations. This paper presents a solution similar to Stowell's which is applicable to pin-ended flange elements. Aspects not considered in Stowell's work, such as the use of elliptic functions to describe the gradual change of mode shape from sinusoidal to essentially linear, and the gradual and asymptotic changes in axial rigidity in the post-buckling range are described in the paper. The paper also presents comparisons between the behaviour of pin-ended and fixed-ended flange elements. Finally, simple strength equations for flange elements in uniform compression based on the first yield criterion are derived.     

高压换热器法兰与内套焊接裂纹原因分析与对策

介绍了氮肥企业高压换热器法兰与内套焊接存在的问题,分析了产生焊接裂纹的原因,提出了解决问题的简便办法。     

519法兰铝铸件的低压铸造

519法兰壳体是大型回转体结构的气密性铸件,其外形尺寸为680mm×364mm,通过低压铸造的生产实践表明,在模具温度为300～350℃,充型压力为0.3MPa,充型时间为20s,保压压力为0.8MPa,保压时间为120s的条件下,可生产出优良铸件,工艺出品率由砂型铸造的50%提高到75%以上,铸件一次气密性检漏合格率达98%以上。由于铸件加工量比砂型铸造工艺减少了5%以上,铸件质量由52kg降低到36kg,每件减轻了16kg,仅此项每年可节约30万元。     

制氢装置水分离器入口法兰及三通失效分析

应用光学显微镜,扫描电镜、光电子谱,显微硬度仪,铁素体测量仪等对开裂失效试样进行分析,结果表明,三通和法兰开裂效是由于氢致开裂所致;同时也具有明显的氯化应力腐蚀破裂敏感性。     

风力发电塔筒法兰生产工艺研究

风力发电塔筒法兰是发展风力发电的重要零部件.本文叙述了风力发电塔筒法兰的技术特征、生产工艺及技术装备,并对法兰生产过程中的关键工序进行了阐述,总结了超大直径环形锻件生产中的经验及注意的问题.     

Non-linear curling of wide single-flange steel panels

An original analytical model to study the non-linear flange curling in wide single-flange panels is presented in this paper. Flange curling phenomenon is the tendency of the wide thin flanges (in compression or tension) to move towards the neutral axis, when thin-walled members are subjected to bending. Despite the simplicity of the formula developed in earlier works of Winter to account for the flange curling effects, which is used in current steel codes, recent work has showed that this expression is rather restrictive and does not apply for all cases. The analytical expressions reported here are rather general since they (i) consider the restraining effect provided by the web, (ii) account for the shift of the neutral axis due to curling, (iii) incorporate the decrement of the second moment of area due to curling, and (iv) are fully analytical, thus avoiding iterative techniques. The analytical model is applied to study the curling behaviour of profiled steel decks and cassette-wall panels and is validated by means of comparisons with experimental results available in the literature. Since the EC3 rules state that the tensioned wide flange in liner trays should be reduced if the curling displacement is higher than 5% of the web height, approximate expressions to evaluate the reduced width of the wide thin flange under curling are proposed.     

Explicit formulae for the flange efficiency of curved beams

Deformation of the cross-section of a curved beam of thin-walled open section, such as a channel-section formed from thin sheet material, leads to loss of stiffness due to reduced effectiveness of the flanges. Explicit formulae are derived for the flange efficiency of curved beams of channel, Z– and I–section, in which the geometric parameters on which loss of flange efficiency depends are easily identified. The formulae are readily adapted for curved beams of composite material, identifying also the particular properties of the laminate that relate to flange efficiency. The formulae are approximate, but nevertheless of good accuracy in the practical range of designs.     

法兰带压堵漏夹具设计浅析

在法兰注剂式带压堵漏中,夹具的设计是堵漏技术中的难点。以GB 150—1998《钢制压力容器》壁厚计算公式为依据,综合考虑注剂螺栓孔减少夹具截面积对夹具强度的影响和夹具刚度的要求,推导出了更接近实际的夹具强度计算公式。     

A study on the sealing performance of bolted flange joints with gaskets using finite element analysis

Gaskets play an important role in the sealing performance of bolted flange joints, and their behaviour is complex due to nonlinear material properties combined with permanent deformation. The variation of contact stresses due to the rotation of the flange and the material properties of the gasket play important roles in achieving a leak proof joint. In this paper, a three-dimensional finite element analysis (FEA) of bolted flange joints has been carried out by taking experimentally obtained loading and unloading characteristics of the gaskets. Analysis shows that the distribution of contact stress has a more dominant effect on sealing performance than the limit on flange rotation specified by ASME.