古建筑木结构榫卯节点采用碳纤维布加固模型振动台试验研究

对宋代殿堂式木构建筑心间缩尺模型已残损的燕尾榫节点用碳纤维(CFRP)布进行加固,并进行模拟地震振动台试验。选用El Centro波、Taft波、兰州波作为输入地震波,采用多点多指标同步测量柱根、柱头、斗栱的地震响应,对CFRP加固模型结构的破坏形态、动力特性、耗能能力进行分析。结果表明：CFRP加固模型的自振周期T的变化范围在0.53～0.67 s之间,阻尼比ξ的变化范围在2.8%～4.6%之间,随着地震激励的增加而增大;加固模型的动力放大系数 β 小于1,随着地震激励的增加而减小;模型的铺作层、柱础层通过摩擦滑移来耗能,柱架层的耗能能力最强,在模型整体的耗能、减震中起着主要作用。     

热轧钢板组合楼板在CCTV主楼工程中的应用

针对热轧钢板组合楼板的结构特点,以CCTV主楼悬臂组合楼板实际工程应用为例,阐述了热轧钢板组合楼板的设计、钢板加劲板设置、钢板拼焊和与构件连接构造、组合楼板加工和安装、楼板混凝土浇筑及钢板底面涂装施工等内容.结果表明热轧钢板组合楼板性能良好,满足相关规范要求.     

广州某电缆隧道明挖段施工监测

结合广州220 kV厚德变电站明挖段电缆隧道施工安全监测实例,系统地介绍钢板桩加钢支撑支护体系中施工安全监测设计、监测仪器设备的安放、隧道明挖法施工过程的实时监测频率、监测警戒值确定及监测报告等内容。并介绍一种新的监测方案在特殊施工场地的应用,根据现场实时监测数据,特别是异常数据的分析及安全预测,针对其结果采取相应的处理措施,避免了工程事故的发生,确保了施工现场和周围环境的安全。     

深基坑施工技术

上海宝钢化工煤气系统技术升级改造工程煤气精制部分共有深基坑4个,深度在4～7m之间;按宝钢规定属于危险性较大的分部分项工程;基坑施工采用深井降水加拉森Ⅳ钢板桩共同进行,工程实施顺利,表明其技术是可行的。     

回转体金属板料渐进成形制件残余应力研究

内部残余应力分布是影响成形制件品质的重要因素。通过分析金属板料渐进成形制件内部残余应力产生的原理,建立其残余应力的测量评价方法,研究制件内部残余应力性质及分布规律,进而提出残余应力对成形制件品质的影响,制件内部分布的残余压应力可以明显提高金属抵抗疲劳的能力。试验结果表明,针对回转体金属板料渐进加工制件,其内部存在着残余应力,性质为残余压应力,大小随制件轮廓半径的增大而减小,且与制件轮廓半径呈非线性关系。     

基于CNCKAD的钣金件制造技术

为实现钣金件的数字化制造,提出了钣金的数控冲压加工,研究了基于CNCKAD软件的数控程序编制问题。首先,选择典型的数控冲压设备,编制冲压加工工艺;然后,建立制造数学模型,定义编程操作,生成数控机床用的加工程序;最后,通过实例仿真加工,验证了所述方法的可行性和正确性。     

Wear Behavior of Al-Si Alloy Impregnated Graphite Composite

Pin-on-disk type unidirectional sliding wear experiments for an Al-Si alloy impregnated graphite composite (pin) in contact with a bearing steel (disk) were conducted at various contact loads in wet and dry air to investigate the wear behaviors in detail. The pin-lifting phenomena of the composite as observed. The height was constant at lower loads and increased with load. The entrance of wear particles into the contacting surfaces brought about the pin lifting. Mixtures of graphite powder and wear particles adhered to the sliding surface of the bearing steel, resulting in the formation of wide, compacted surface films. The mean thickness of the films increased with load to a few micrometers. The composite exhibited better wear resistance than the matrices in wet air and the wear rate decreased especially at high loads. The wide, compacted films together with the pin-lifting phenomena prevent metal-to-metal contact, achieving a good anti-wear condition. On the other hand, the surface films that adhere in a scaled fashion in dry air have little wear reduction effect.     

Analysis of Tribological Performance of Cu Hybrid Composites Reinforced with Graphite and TiC Using Factorial Techniques

In this study, a copper hybrid metal matrix composite reinforced with graphite (5, 10, and 15 vol%) and TiC (5, 10, and 15 vol%) was processed by a powder metallurgy route. Optical micrographs confirm the uniform distribution of reinforcements in the copper matrix. The hardness of the composites decreased with the addition of graphite. However, the addition of TiC into the copper matrix increased the hardness of the composites due to its high hardness. The influence of graphite percentages, load, sliding speed, and sliding distance on the wear of the as-sintered hybrid composites was studied based on the design of experiments. Analysis of variance (ANOVA) was used to study the effect of the parameters on the wear weight loss of the hybrid composites. The weight loss due to wear of the hybrid composites decreases from 0.1345 to 0.0830 g as the volume percentage of graphite increases from 5 to 15%. Results indicated that the normal load has greater static influence of 43.85%, sliding distance has an influence of 29.84%, percentage of graphite has an influence of 15.17%, and sliding speed has an influence of 1.83% on the weight loss of copper hybrid composites due to sliding wear. The worn-out surfaces were analyzed using electron microscopy, which reveals that the addition of both hard ceramic reinforcement TiC and soft solid lubricant graphite significantly improves the tribological performance of the copper composites.     

304不锈钢板料激光热应力成形试验研究

通过改变激光功率、扫描速度、光斑直径、扫描次数及板料宽度对2 mm厚度的AISI304不锈钢板料进行激光热应力弯曲试验, 分析了各工艺参数对弯曲角度的影响规律, 对工件表面烧蚀情况进行评价, 并对板料金相组织进行观察分析。试验结果表明: 在试验参数范围内激光扫描次数、光斑直径、扫描速度和板料宽度对弯曲角度呈近似线性规律, 而激光功率对弯曲角度的影响不呈线性规律; 较大的面能量密度产生较大的弯曲角度。可通过工艺参数的合理组合在保证板料表面质量的前提下采用较大的面能量密度进行扫描以提高弯曲变形的效率。以上研究为精确控制板料激光弯曲成形奠定基础。     

彩色涂层钢板涂料热风加热固化的节能

对彩色涂层钢板生产中涂料加热方法进行了比较,回顾了实现节能的历程。介绍了一种在低氧含量的惰性气氛下利用废气循环热风加热固化的新技术及使用效果。