电站锅炉集箱管座接头焊缝裂纹分析

通过外观检查、成分分析、性能试验、金相诊断、电镜研究等方法对电站锅炉炉膛竖井转水平烟道处水冷壁下集箱管接头(材质为15CrMo)焊缝裂纹进行了失效分析.结果表明,集箱管座接头裂纹断裂属性为韧性,其成因主要是设计安装结构不合理,集箱和管束间温差大而造成应力集中所致.     

预精焊机组管端焊缝拍片的改进与应用

针对原管端焊缝拍片工艺流程不能满足预精焊机组生产节拍的问题,给出了解决问题的方案,并对设备改进前、后使用情况进行了分析和对比.结果表明,改进后的钢管管端焊缝拍片设备满足了预精焊机组的生产节拍,提高了机组生产作业率,减轻了操作人员的劳动强度,减少了X射线对操作人员的伤害,达到了预期的效果.     

Stochastic seismic wave interaction with a rock joint having Coulomb-slip behavior

Seismic wave interaction with a slippery rock joint with an arbitrary impinging angle is analytically studied based on the conservation of momentum on the wave fronts. Based on the displacement discontinuity method, the wave propagation equations are derived for incident P- and S-waves. By comparison, the calculated transmission and reflection coefficients for normal incident waves are the same as the existing results, which proves the wave propagation equation obtained in the paper is correct. The wave propagation derived in the context can be applied to incident waves with different waveforms. Stochastic seismic waves are then used to analyze the seismic wave interaction with the slippery rock joint, where the stochastic seismic waves are generated from frequency spectra. The parametric studies are carried out to investigate the effect of type, intensity and impinging angle of the incident seismic waves on the wave propagation across the slippery rock joint.     

锁骨钢板治疗肩锁关节脱位的随访研究

目的对锁骨钩接骨板治疗肩锁关节脱位进行随访研究。方法对我院收治的TossyⅢ型肩锁关节患者采用锁骨钩接骨板的方法进行手术治疗,采用L'Insalata评分和Constant评分对治愈患者肩关节的功能进行随访研究及比较分析及。结果本组患者切口均一期愈合,无感染,断钉;患侧的肩锁关节的功能与健侧比较,差异没有统计学意义(P>0.05)。结论采用锁骨钩接骨板治疗肩锁关节脱位(TossyⅢ)具有显著疗效。     

ENIG焊点的失效机理及镀层重工方法研究

采用显微形貌、微观结构和元素成分分析等物理分析方法,以不同类型的化镍浸金(electroless nickel/immersion gold,ENIG)基板为对象,分析了其焊点在不同情形下的失效模式和失效机理,阐述了"黑盘"缺陷的主要失效特征,研究了具有黑盘缺陷的化镍浸金基板的重工工艺.研究结果显示,Ni层断裂表面单一的高P含量或轻微Ni层腐蚀不能作为黑盘缺陷的唯一依据,已形成良好金属间化合物(intermetallic compound,IMC)层的Ni层腐蚀位置的焊接界面仍具有良好的机械结合强度,采用喷锡工艺(hot air solder level,HASL)对具有黑盘缺陷的化镍浸金基板进行重新处理切实可行.     

后浇带渗漏问题在设计与施工阶段的预控

分析了混凝土后浇带的作用,提出了从设计、施工两大环节控制后浇带质量的具体措施,以确保混凝土结构工程质量.     

Improved one-dimensional beam model for unbalanced composite single-lap joint

An analytical nonlinear solution was provided for unbalanced composite single-lap joint (CSLJ) using an improved one-dimensional beam model, which incorporated the effect of bending–tension coupling. The bending–tension coupling stiffness was introduced to characterize the coupling bending and tension behavior induced by the un-symmetric stacking sequence of composite laminates. The governing differential equations captured the bending–tension coupling behavior and the geometrically nonlinear features were constructed based on the displacement compatibility conditions of flexible interface. The transverse deformation in overlap region, edge moment factors and adhesive stress distributions for the unbalanced CSLJ with inflexible, intermediate flexibility and flexible adhesive can be determined by the present one-dimensional beam model. The accuracy of the present model was validated by the comparison with nonlinear finite element model. The effect of bending–tension coupling on edge moment factors and peak values of adhesive stresses was shed light on with the present model.     

Optimal design for concrete pavement situated above box culvert: experimental and numerical study

This study examined the pavement distress data obtained from the field as well as the effects of the soil cover depth, joint position and reinforced slab length on the behaviour of concrete pavement using the finite element method. An ultimate strength model with a similarity of 1/2 was designed and constructed. Finite element analysis incorporating an implicit direct numerical integration scheme was conducted to obtain an optimal design for the pavement structure above a box culvert. An accelerated pavement test was conducted for validation, in which a realistic traffic load was imposed on the pavement model constructed in the laboratory. The strain histories were measured at each section and compared with those of numerical analysis. The optimal joint position and reinforced slab length that can minimise the damage to the pavement structure above a box culvert were also determined.     

Creep and tensile properties of press molding joined GMT-sheets

GMT-sheet is used in automobile bumper with high rigidity and strength, and its joining strength is influenced by lap length, one of the joined molding conditions. Fracture strength was calculated by dividing fracture load with cross-sectional area. Total five repeated measurements were made to obtain the average value. Tensile test was conducted at room temperature for 10 specimens. In addition, the effect of compression ratio on creep and tensile performance during lap joined molding was discussed. With increasing lap length, the lap joining efficiency of GMT-sheet was increased. However, higher compression ratio reduced the joining efficiency. Creep test on GMT-sheet showed abrupt fracture without tertiary creep. This can be explained by the weak thermal resistance of the resin. If GMT-sheet was exposed to high temperature for a long time, it was easily failed by external force.